ZX Spectrum stuff International youth work Porsche 924 Misceallous

View My Stats
ZX Spectrum in the 21st Century?

Dear Visitor!

After 10 years of continuous hard work, this site is become the ultimate source of present ZX Spectrum hardware and software. Also it is the ’bridge’ between amateurs, professionals, sellers, buyers etc. In a sentence: gives a great help to keep the Spectrum alive.

If you want this website to survive and alive, and you have some capacity to help me, please contact me at tarjan(a)uw.hu e-mail address. Thanks in advance!

Magyarul/In Hungarian · Angolul/In English · Galéria/Gallery
Didaktik M 48/128 and Kompakt 48/128/Professional Slovakia Czech Republic

Didaktik Skalica company was founded in 1971 in Bratislava in the ex-Czechoslovakian Republic. Primary profile of company are school accessories, but they were tasting also into the computer industry.

Their very first computers -Didaktik Alfa and Beta- weren't ZX Spectrum clones. In fact, the same happened as in most Central-Eastern European ex-socialist countries: at the company realised, can be a far better business to copy the ZX Spectrum with its thousand of games (or even it is reached ten thousand?) rather than developing completely new machines. In that way were born the Didaktik Gama 87, 88 and 89. By the way, these machines were quite popular in Poland too.

The company - thanks to the still high PC prices in the former Czechoslovakia - launched his two last ZX Spectrum clones in early 1990s after Gamma series. These were Didaktik M and Kompakt. Parallel with the machines were released the D40 (5.25 inch/DD/360K) and D80 (3.5 inch/DD/720K) disk systems.

In 1994, Didaktik Skalica moved to PCs, and sold the right of manufacturing and distributing to Kompakt Servis (Kompakt Services) in the Czech Republic, which was a single man enterprise and the machines were sold until 2008.

The Didaktik M was appeared in two versions. Versions from 1990 and 1991 are differing primarily in the controlling system of the keyboard. The Didaktik M was made in higher quality as the Gama series with ergonomic casing and keyboard (with separate cursor buttons) and this was created them a more professional looking machine, than they in reality.

The hardware was undergone an extensive redesign. The task of ULA was taken over by the Russian Angstrem T34B1 circuit and the ROM chip (T34RE1), which was also came from them. This system was actually the ancestor of today's chipsets. The RAM was used a single 64K chip of 48K, so there was no separate fast and slow memory.

Thanks to all of these, theoretically it would be more compatible with Russian clones, yet it was able to achieve almost 100% ZX Spectrum compatibility.

One of the two joy ports is Kempston and the other Sinclair compatible, but their "connectors" (which in reality the part of motherboard) is only compatible with the Didaktik joysticks. The cassette unit and power supply are both DIN standards. The picture output is TV or monochrome composite. There is also present a Sinclair compatible edge connector.

Didaktik Kompakt from 1992 is a Didaktik M with built-in D80 drive. Another novelty is the RGB output via Scart socket, as well as a parallel bus and a system edge connector. The power supply was also installed in the computer’s case. The Snap button of D40 and D80 floppy drives can be accessed through the keyboard. Joystick connectors has returned to the Atari standard.

The ROM used in these machines was reused in several ex-Soviet clones.

Kompakt Services was made two big bros of these machines by using their motherboards. Didaktik Kompakt Professional is a machine built into a PC-case with two 5.25-inch drives controlled by the D40/D80; the Melodik, Kempston Mouse and PC keyboard interfaces were also integrated into the system.

The Didaktik Kompakt 128 uses a Didaktik M motherboard expanded to 128K. The built-in D40/D80 interface here controls two 3.5-inch drives. The Melodik, Kempston Mouse and PC keyboard interfaces are present in the same way as in the case of previous one.

Updated: 2018. October

Didaktik M 1990
Didaktik Kompakt 1992

Didaktik Gama 192KB, Didaktik Gama 256KB Millennium Edition Czech Republic

Didaktik Gama 192K is the project of the Czech Petr Valecko (ie CSS Electronics) aimed to to build a 100% 128K compatible clone based on Didaktik Gama 89.

This has succesfully achieved as the 'basic components' are the same: a Z80A processor at 3.5MHz and AY-3-8912 sound chip - the latter being tuned to ACB stereo in accordance with the former Czechoslovakian habit. In addition, standard RS-232C and parallel ports are also found on the motherboard. As can be seen, the size of RAM size was grew to 192K. ROMs are available from 32Kb EPROM 27256C.

In addition, the snowing effect of ULA was also successfully avoided and the TV signal and tape input quality was improved too.

The motherboard is designed in that way, that old parts can be refitted into it and the board can be easily installed into the original Gamma case. Of course, the motherboard itself also higher quality than the original. Interestingly, the video memory is placed on a separate card, and attached to the motherboard with a spacer.

Designing was made from November 2003 to March 2004.

Three subversions are exists: v1a (never was released), v1b and v1c.

Petr was also offered a limited version, it was called Didaktik Gama 256KB Millennium Edition or Didaktik Gama 256KB Nemesis. As can be expected, the most important innovation here is, that the RAM was expanded to 256K.

Updated: 2018. November

Didaktik 192KB v1c board
Didaktik 192KB v1c assembled

Pentagon 48/128/256/512/1024/SL/Turbo and compatible interfaces Russia Ukraine Czech Republic Poland

Very first Pentagon machines appeared in 1989 in Moscow (ex-USSR) with 48K RAM, later with integrated Beta-128 disk interface.

In 1991, the first version of 128K Pentagons came out (Pentagon 128K v1) without the AM/YM chip. It was because only this chip does not have Russian analogue, so was quite hard and expensive to obtain. But the sound chip can be installed later with an AY-adapter. This card incorporates the AY/YM chips and the Z80 processor, and must be plugged into the socket of Z80 in the mainboard.

They already have the Centronics compatible Lprint MKIII interface integrated onto the mainboard. These machines were not equipped with the original Sinclair edge connector.

The Pentagon 128K v2+ from the same year was identical with the previous one, but AY/YM chips were installed as standard (v2 does not exist!). This subtype was jointly developed by ATM (Association of Technology and Microelectronics) and MicroART (or MicroArt) corporations, which were also developed the soonly detailed ATM clones. From here comes its another names, the ATM 128 and ATM 1991. Sadly, it is quite buggy, but as rumours said, with some home fixes can be turned into compatible with original Spectrums. We know about two such mods, both developed by Z. Their names was given from the year of the modifications: Pentagon 128K Z1992 and Pentagon 128K Z1994.

Nickname of Pentagon v3(+) is Pentagon Solon or Pentagon 1993, and of course it is also incompatible. It was inheriting its name from Solon's company. In that case, engineers were optimised the screen output quality. But everything has its own price....

From the firm briefly: Solon is located in Moscow and was a real universal computing enterprise: spreading programmes, publishing computer literature, making some hardware developments: all of those were fits in their profile. At present, it working as a publishing house under Solon-Press name.

Some sources are speaking about a further development (for example Pentagon v4) but nobody trusted its existence so far. Very probably, this improvement was made in the smaller countries of ex-USSR (for example in Ukraine). At least, in the city of Licichanks in Ukraine saw the light a Pentagon development, which was realised on a 25x40 cm mainboard with more than 100 elements. Due to its size, only can be built into a tower case and was very unstable. Since 2002 no news. Maybe this was the v4 Pentagon, maybe not.

One thing is sure: with increasing the version number, number of ICs on the mainboard became less and less, but still much more than in the original Spectrums. Real Russian design...

Pentagons got their names about the pentagon layout of the conductors ground circuit on the initially introduced 48K mainboard. Following 128K models do not have this layout, but the name remains the same.

They soon became the most widespread models in Russia, thanks to the easy building and expanding - and of course for the relatively cheap price. In addition, all documentations were freely spreadable. Between 1991 and 1996 they became the mainstream machines of Russian computing.

Both individuals and companies manufactured Pentagons. So Pentagons can look very different (convenient home computer like, desktop, mini-tower etc.) and the quality also can vary in very different ranges.

Another key of popularity of the machines were easy expanding and tuning - even the strangest modifications can be done home made.

The "default config" became the Pentagon 128+AY+Beta combination with a cheap AY-stereo tuning, but some special software uses the extreme Pentagon enhancements. For example, the 512x192 pixel screen, the 128-colour mode, the 256K, 512K 1024K or 4096K RAM expansions, and even the 1,7Mbyte HD disk, real time clock, IDE interface etc. They were mostly end user programs (commanders, word processors, painting programs etc.). These machines were mainly owned by programmers and swappers.

Among ancient time Pentagons, the most powerful was Pentagon 512K Turbo. It has 7MHz Z80B or H processor, two floppy drives and Kempston mouse as standard. From standard Pentagons, it was quite hard to tune-up, needs much time of works.

Instead of 512K modding -because of its being complicated- most users were choose the Pentagon 1024K update (with 1 piece of SIMM module). Let's see the so far known 512K and 1024K tunings.

The 512K RAM tuning had two variants in the early days. In the case of first, RU5 (4164) chips have to be replaced by RU7 (41256). This is the circuit diagram of Hacker Rasp, who is Klimus Vladimir's from 1997.

The another was made of using a single 1 megabyte SIMM module, that was made by Prusak (alias Sergey Bagan) in 2002.

In both cases possible to configure the memory to 1 megabyte according to the scheme of more advanced clones, like ATM Turbo, KAY and Profi.

On the 8bit.lt website was released the Pentagon 512K SRAM upgrade from Hysk in 2015. This offers several advantages over the above. On the one hand, it does not require the modding of the motherboard, and on the other, it has a lower consumption. First, the RU5 chips have to be removed from the board and then one more capacitor. This is followed by wiring together the circuit board and the motherboard, which means only three wires. It is possible to disable the memory above 128K with a simple switch. Also possible to use it as an 1 megabyte upgrade, of course, you need a 1 megabyte SRAM chip, and also needed to replace the controller chip.

The by default 1 megabyte upgrades are the following, all of which using a single SIMM module.

The first one is from 1999, called SIMM & Speccy by Vasilij Jurevic Klimov, also known in the scene as JtN, Bolek and Mielophone.

A similar circuit pattern is followed by Ivan Mak (WingLion, KryLev) in the same year, he is the person taking part in the development of Sprinter.

In 2000, Alone Coder (AlCo - Dmitry Mihajlovic Bystrov) came up with a similar development, and that leads us to the Pentagon 1024 chapter.

The development of Pentagon 1024SL versions were made by Aleksej Sergeevic Zabin (King of Evil, KoE) living in Moscow. Motherboards were manufactured in Zelenograd.

The Pentagon 1024SL v1.x, developed between 2004 and 2005 on the basis of the Pentagon Solon, and consist of total 78 chips. The memory addressing is KAY 1024 compatible, also with one single SIMM module. Actually, it is regarded as the successor of KAY 1024. This is confirmed by the fact, that it is uses the bus system of KAY, the Nemo bus, and has two such slots on the motherboard. From here comes the SL name. Kempston joystick and mouse compatible, also implemented a hardware-level ZX Lprint III support. The latter is not taken out as a port, because it does not used by anything except of old printers.

As standard, it only runs at 3.5MHz, although Lord Vader (LVD-Vadim Alekseevic Akimov) has made an expansion for it, with it can run at double speeds. The Beta-128 interface also works at double speed - this feature is already enabled by default.

Development of Pentagon 1024SL v2.x goes back to 2006. In this case, the 1991 Pentagon 128K operation is simulated by the open source firmware of Altera EPM7128SLC84, which also can be flashed.

Two new graphics modes were also integrated for the request of Alone Coder. One of them is the 16C, the another is Pentagon Overscan mode.

The RAM size remained 1024K, but it handling the 3.5/7MHz turbo mode as standard, but the turbo of Beta-128 was turned off. Lprint III support is also partial here.

You can get the picture on a monitor (VGA-RGB) or TV (with the help of a PAL/NTSC encoder). The AY/YM audio is outputted via a 2x0.5 watt amplifier by a stereo jack. This one has three Nemo buses and the motherboard can be built into a standard PC/AT board.

An alternative firmvare has also been released for it, which essentially offers new features in the graphic modes. It supports the 512x292 resolution, GigaScreent, hardware multicolor, and a new 320x256 mode instead of the Pentagon OverScan (384x304), which can be implemented very complex (it only uses the horizontal Border area). In the 16C mode, hardware scrolling is also supported, and the color palette was expanded to 4096 colors.

In 2007, was released the Z-Controller, an interface for the above machines. This expands the machine with PS/2 keyboard and mouse, SD card, Ethernet, RTC, IDE and USB functions.

The Pentagon 1024SL v2.666 was debuted at DiHalt 2009 party, already integrating the above card. There are two subversions of this. Standard v2.666 and v2.666LE.

The processor is a Z80 compatible Z84C0020VEC at 20MHz, but in the Altera Cyclone II EP2C8Q208C8N FGPA is emulated a Z80 compatible T80 core too, which runs at a maximum of 28MHz. Beside 28MHz, it also can run at 3.5 or 14 MHz. The size of the memory (SRAM) is freely configurable from 512K to 2048K.

Peripherals are controlled by a 16/32 bit ARM LPC2294HBD144 controller. Of course, the picture is come via a VGA out, at a maximum resolution of 800x600 with the possible 256 colors. YM2149 emulation is also the task of FGPA. The audio also has hardware supported mp3 decoding.

The Ethernet part is based on the RTL8019AS chip. It contains real time clock and Nemo compatible IDE controller - thanks to the Z-Controller.

In the Light Edition the Z84 CPU and the Ethernet controller are missing. The control of peripherals is performed here by an ARM LPC2368FBD100. The motherboard is only double layer against the original four-layer design.

Was released a firmware update in January 2013, which supports the memory management of Pentagon 1024, ATM Turbo 2 and Pentevo. Screen modes include ATM Turbo 2 compatible modes: 320x200x16 and 640x200 resolutions. Other enhancements: Turbo Sound and the Reset Service emulation which was originally made by Mr. Gluk (Renat Farhulin Mamedov); as well a copier and debugger program.

8, 16 or 32K cache could be obtained for Pentagons, which are works fine with turbo mode too. With this, speed of processor is not 1.4x of the original in turbo mode, but could boast double speed.

Those who had only original Spectrums, the Czech Velesoft is offering some alternatives. The internal Pentagon 512 interface can be built into the ZX Spectrum 128K+2. Later he constructed its cost effective external version for ZX16/48 users with External 128-512K upgrade for ZX16/48K name. The ZX Profi interface also offers Pentagon compatible mode. More informations at the Velesoft section!

The Polish Jarek Adamski also constructed a similar interface, called ZX4MB, which will detailed later too.

The Pentevo (NedoPC) and Pentevo Light (Mikhail Tarasov - Mick) series can be regard as the successors of the original Pentagons.

Updated: 2018. October

Pentagon 128 v1
Pentagon 128 v1 with YM chip upgrade
Pentagon 128 v2+
Pentagon 128 v3(+)
Pentagon 512K SRAM upgrade
Pentagon 1024K RAM upgrade
Pentagon 1024 v1
Pentagon 1024SL v1.00
Pentagon 1024SL v1.4
Pentagon 1024SL v1.41
Pentagon 1024SL v2.2
Z-Controller v1.0
Pentagon 1024SL v2.666
Pentagon 1024SL v2.666LE
Pentagon 512 interface
Profi interface
Pentevo rev C
Pentevo Light

Scorpion ZS 256 Russia Czech Republic

Scorpion computers are the products of Zonov and Co. from Leningrad. The company was started the computing business with his Leningrad clones in 1988. By the way, this machine was revitalized by enthusiastic amateurs, and you can be read it about later. The chief of company was Zonov Sergey.

Like Pentagons, circuit design of these machines were not protected, anyone could freely copy the developed motherboard. Thanks to this, various variants of Leningrads were also the first widespread clones. They were also became the basis of KAY machines.

However, 1991-92 was a year of the true milestone in the ex-Soviet Union. At this point, the new trend was for the manufacturers, not only to copy the ZX Spectrums, but launch more powerful machines under their own brand named.

That's how the Scorpion ZS 256 clone was born in 1991. In its name, ZS refers to the boss. Actually, we are talking about motherboards, which can be built in any PC-case. The company - like other enthusiastic amateurs – mostly installed them into mini towers, but of course they could also be purchased as a separate boards.

In fact, only Scorpion succeeded to conquer the market alone: besides Pentagons, it was the only other machine that reached the most dominant sales in Russia. Moreover, according to surveys, it has taken the leading place from the second half of the 1990s. The manufacturer did not made public the Scorpi, but production, development, distribution and service were carried out by the company itself. The name of the new clone has also become the name of the company.

From its name, easy to guess, that it contains 256K RAM, and beside this, got 64K ROM. First one can be expanded up to 1024K or even to 2048K with GMX board.

It uses a simplified version of Beta-128, which handles maximum two floppies, but these can be operated with turbo speed. Initially, of course 5.25 drives were used. It has a serial RS-232C and parallel Centronics (printer) ports and pre-installed AY chip. There is one or two Nemo buses, but with a bus extension, it can be increased to three.

Unlike other Russian clones, completely compatible with ZX Spectrum.

In the ROM pack, the Service Monitor was built-in by Andrey Larchenko (Andrew Moa). This can be activated with the so-called Magic Button.

The first Scorpion ZS 256 contained Z80A processor, running at 3.5 MHz. Its successor, the Scorpion ZS 256 Turbo+, which was released in 1996, is working with twice processor speed thanks to the Z80B. In addition, was received a masked motherboard, of course its size also decreased.

These clones were manufactured until 1998 and then the company was switched to PC-compatible machines and the distribution of office supplies along with the sale of the remaining stock.

There are several factory Scorpion expanders were released for it, such as SMUC, GMX, General Sound, Midi-SC, IBM PC Keyboard and Mouse Controller.

Europeans also do not have to worry, because with Velesoft's above-mentioned ZX Profi interface, the ZX Spectrum 128 can be turned into Scorpion ZS 256/1024.

Updated: 2018. November

Scorpion ZS 256 mainboard
Scorpion ZS 256
Scorpion ZS 256 Turbo+ mainboard

KAY-128, 256, 1024 and their clones Russia

KAY computers (more precisely motherboards) were the products of Nemo Company residented in St. Petersburg. The company was leaded by Vyacheslav G. Skutin, aka Captain Nemo.

He was also the editor of ZX-Format magazine in the classic age. Above that, he was also published in the Abzac magazine and in the Open Letters diskmag. In his articles, he was questioned the worthing of technological development. For example, in a very strange way, he was rejected all computer networks, even he did not had e-mail address or web page.

His first prototype was Composite 48K, intended as the rival of the Leningrad clone. Also was known under the Leningrad+, Composit, Composite 48K, ZX-Comp 48K names.

This was followed by the first series production the originally Composite 128K+AY named clone. According to rumors, last three letters are the origin of the KAY name, so they are also known as KAY-128. It did not had floppy drive, but contained the AY chip. By the time it was appeared, unfortunately became unsaleable.

Anyway, the concept of machines designed by him followed this concept: all extensions, what did not existed for the original ZX Spectrum 128K, were realized on a separate card.

This is how the Nemo bus was replaced the Sinclair edge connector. Unlike its predecessor, this does not allocates the resources equally, when multiple peripherals are connected to it. The highest priority is the first slot, the second is the middle, and the lowest priority is the third. For all new clones and peripherals, Nemo bus became standard in the former Soviet Union. Its alternative name is ZX-Bus, but it does not confused with the another ZX-Bus, built by the Swedish Sami Vehmaa.

The bus is slightly differs on different clones. For example, in case of first Scorpion versions, pin 5A is the backup, and in the following releases, it is giving the +12V for expansion cards. It is not used on the green colored turbo motherboards. In case of KAY machines, the 14MHz signal is here. For ZX Profi, the bus system is the same, but it has not edge connector, but an IDE-style one.

The KAY-256 Turbo was released in 1994, born as the rival of Scorpion ZS-256, and also has compatible memory mapping. A total of five versions were released until 1997. Versions 1.0 and 1.1 had two expansion ports (KAY-256/2SL), versions 1.2 to 1.4 had three one (KAY-256/3SL). V1.4 also has turbo mode.

Description of KAY-1024/3SL/Turbo was first published in the 8th issue of ZX Format diskmag (1997 December).

It has 7MHz full travel turbo mode, ie turbo mode could not be switched off. Beside that, it was the fastest turbo clone, this was leaded to be incompatible with more or less games and demos. RAM can be used in two ways: full 1024K or 256K+RAMdisk. In its era, was a praised for its price, quality and performance ratio.

It is compatible with Kempston and Sinclair joysticks, plus has a Centronics connector. Of course, the manufacturer offered special Beta-128 Turbo and IDE controllers with Nemo-bus. Likewise, you could also order XTR modem, PC keyboard interface and General Sound sound card with Nemo-bus.

In August 2003, Nemo announced, that he will close the company, unless does not receive minimum of 50 orders for the KAY-1024 until January. Finally in 2004, he left the platform temporarily.

Briefly about the successors. Pentagon 1024SLv1.x was already described.

The only half-ready Ant-1024HD development uses the Altera EPM7128SLC84-15 circuit for the realization, like several other Russian clones. Its last known version is V11 in October of 2009. By the way the development was started in February 2005.

The machine includes Kempston joystick, keyboard, monitor, printer and cassette recorder connectors. The HD name indicates, that hard disk also can be attached to the machine, so the IDE controller can also be found on the motherboard. The VHS cassette-sized board would also have been compatible with the later detailed DMA Utra Sound Card. Of course, it would have 1024K RAM with the 7MHz turbo mode. It could been installed into a box of dead CD-ROM drive. The development was associated with Z.A.N, who is also known as dim.

Also not to be heard about the KAY 2006 NB (KAY 2006 North Brigde), which would have been implemented with the Altera EPM7064 MAX programmable logic circuit by heroy. In addition to the standard resolution, it also offers three another extras: Multicolor, GigaScreen and 512x192 pixels with 2 colors.

Captain Nemo and zst (Sabirzhanov Vadim Mirzhanovich) finally reintroduced the motherboard and it was appeared as KAY-1024T/4SL (KAY-2010). The NemoFDC (ZXkit-010) and NemoIDE (ZXkit-011) cards have also been produced either in a premium or a standard quality. Compared to the original board, the keyboard and Kempston controller has also been improved. It accepts SIMM30 modules and the ATX power management was also implemented.

Updated: 2018. October

Composite 48K (1988)
Composite 128K (1993)
KAY 1024T/3SL (1997)
KAY-1024T/SL4 (KAY-2010)

Sprinter 97, 2000 Russia

The Sprinter clone was the product of Peters Plus Ltdlocated in St. Petersburg and manufactured between 1997 and 2004. It was the most advanced ZX Spectrum clone.

This company also had an earlier clone series that was named Peters, and even then the name of the company was Peters in that times. Four main versions of the have been released. Peters MC 64 was a ZX Spectrum 48K clone with built-in printer connector. Peters WS 128 is, of course a 128K machine. Peters 256 is a clone built on the basis of Scorpion. Finally, Contact CPS-128 is a 128K machine with its own unique bus system. The main designer of Sprinter Ivan Makarchenko (WingLion).

The unique feature of the machine in those times was the programmable logic circuit. With this, it can be configured as a number of computers, including the rarely used own Sprinter mode with the Estex operating system. The method was christened by the company as Flex architecture. Additionally, ZX Spectrum 128, Pentagon 128/512 and Scorpion ZS 256 modes were also offered.

A total of 110 motherboards were made. All documentations were became free to use, except of FGPA firmware. NedoPC wanted to get the source code of it in 2005, but Peters asked $10,000 for it.

In February 2007, Ivan Mak on the zx.pk.ru forum was announced, that he will publish all documentations as public domain. Nevertheless, he was made a web page, where he was collected the documentation that was already available so far. Finally, in the autumn of 2009, he was finally also published the FGPA code.

There were two subversions, Sprinter 97 and Sprinter 2000. Finalization of the yellow-brown motherboard of 1997 series is rather "Russian" quality. This is not surprising, as these machines were made manually. The Sprinter 97 was introduced at the Enlight'96 party in Moscow. Version 2000 can be distinguished for the first time by the green color of the motherboard and the quality of the building. Sprinter 2000 has two major versions. The Sprinter 2000 Light Light is a variant of the original version without ISA slots and the half amount of videoRAM.

Motherboards are AT-standard with SIMM72 RAM modules. The two ISA buses were compatible with some PC devices and with their own developments.

Let's see the specifications of Sprinter 97. The processor is a Z80-compatible 14MHz Zilog Z84C15, which runs in ZX Spectrum mode at 3.5MHz, switching between the two modes is possible by pressing F12. The FGPA is the 10,000 logic gate Altera EPF10K10QC208. System RAM size depends on the installed module. The extra memory, of course, can also be used as RAMdrive lettering from e: up to t:. Extra functions can be accessed from the extended version of TR-DOS. The 8-bit stereo sound AY and Covox compatible with quite weak AY-emulation. VideoRAM size is 256KB and can be easily duplicated. The floppy controller is the same KR1818VG93 as already known from Beta-128, which supports 3.5" (720 KB/1.44 MB) and 5.25" (720 KB) drives. Other integrated devices: IDE- and AT-keyboard controller, serial and parallel port (latter one is similar to Centronics). The IDE-HDD controller uses the FAT-16 specification, so we can use maximum 2GB partitions (4 partitions x 2GB, so a total of 8GB on the hard disk). The picture can be outputted to RBG monitors or TVs. In addition to standart Spectrum resolution, it also offers 320x256/256 and 640x256/16 modes.

In Sprinter 2000, the same processor is running at 21 MHz and can also be switched to 3.5 MHz. However, 21MHz is only a theoretical speed, as ULA pulls it back to 16MHz. The video memory is already 512K as standart, and in the Light version, as mentioned already, only 256K. The picture output can be a either TV or CGA monitor, the sound is already 16-bit quality. The FGPA is the 30,000 gate Altera EP1K30QC208-3.

Its variant the Sprinter 2000s from 2003, which has the same specification as the previous one, but has less ICs thanks to the more modern components.

Peters Plus was developed two games (Doom, Thunder in the Deep) and some user programs (Flex Navigator, Audio Player, GFX-Viewer, 2D Studio, etc.) for the machines. Otherwise, all Sprinter software programs are free for its buyers (in fact they are freeware for everyone, but others would not be able to use them :).

The motherboard was spread by postal delivery. The Sprinter was never been overwhelming successes. This was partly due to the high price ($115 for the motherboard, and $170 for ready assembled with keyboard and a mouse). On the other hand, it was perhaps not designed as "real" mass clone, but rather a toy, what was primarily targeted the Western clone collectors.

Using the public domain documents, Sprinter 2003 was created by Ewgeny7 and loxic, which is actually the same as Sprinter 2000s. On the zx.pk.ru forum loxic provides detailed information about assembly.

Updated: 2018. December.

Sprinter 97 mainboard
Sprinter 2000 mainboard
Sprinter 2000 Light mainboard

ATM Turbo Russia

ATM Turbo is an 8-bit computer series. Since aside of ZX Spectrum compatibility, it offers many other innovations, cannot be called a simple clone. Rather, in fact, it is an unique computer architecture, which also offers ZX Spectrum compatible mode.

MicroART (µART) and ATM (Association of Technology and Microelectronics, earlier: Associaciya Tvorcheskoy Molodezhi - Association of Creative Youth) companies in Moscow were begin to work on a clone made from domestic components in late 1980s. This one is became the ATM-128 or, as it is more widely known, the Pentagon 128K v2+. The idea of creation the ATM Turbo machines was brought by several facts. On the first hand, it was unable to control the piracy: many another manufacturers offered various Pentagon replicas. Secondly, they wanted to create a business machine, an alternative to the PCs, similarly to Scorpion and Profi.

This is how the first ATM Turbo model was born in 1991, now known as ATM Turbo 1, ATM Turbo 512K, or simply ATM 1, or ATM 512. Meanwhile they also continued of manufacturing Pentagos.

Due to the relatively high price and the raised compatibility issues, they were not became widespread. The motherboard of the machine was complex enough to prevent copying it illegally, mainly because of the video controller with its many novelties.

So in spite of these impressive innovations, however, the breakthrough success was not achieved. The relatively high price (5-10 of average months salary in Russia) is not necessary to explain. Compatibility problem is much more interesting. Compatibility issues of Pentagons was successfully corrected by the designers (meaning the memory management is fully ZX Spectrum 128K compatible), but this also become a great disadvantage. When the time it was released, already the timings of Pentagons became the de facto standard. So the machine did not run the modern-day ex-Soviet programs properly.

ATM machines were considered to be the best ZX clone by their users and those, who can only dreamed about it. On the first hand, they are fully Spectrum 128K compatible (running of classic programs), and on the other, with Beta-128 interface was made it available of using new Russian programs. And CP/M mode allows you to run many user programs. ATM Turbo 1 was numbered from 4.10 to 5.20.

The v4.10 motherboard was quite buggy. Version 4.20 was too, for example, was unable to connect an ADC (analog-to-digital converter) to it. It can be considered error-free from 4.40. However, for running CP/M, had to patch from the 1.00 BIOS. This is also true for the previous boards. The 4.50 was similalry error-free. Here, the 1556HL8 PAL encoder was replaced with a DIP24 socket variant. Version 5.20 was the same, but supported the 64-key extended keyboard and all connectors were soldered onto the motherboard. So can be considered functionally completed.

In 1992, a new model was begin to advertised, the ATM Turbo 2. In the next year, disagrement was arised between MicroART and ATM, and they stopped the co-operation. Second series of machines were numbered from 6.00 to 7.10. From this point, we can talk about two subtypes of ATM Turbo 2. One of them is the short-lived version of ATM, and the another one is developed by MicroART.

ATM after releasing his own Turbo 2 in which, for example, put a different ROM (containing CP/M instead of the adopted version of MSX-DOS), soon stopped production. We know little about their version 6.00. Only that, it had a lot of bugs and the IDE controller was appeared on this motherboard. A number of bugs were reduced in the never went production 6.10, and they can fixed with about 30 wires. For using a PC keyboard, needed to add the 555TM2 chip. 6.15 is the same, but the (c)MikroART script was removed from the page.

Meanwhile, MikroART was continued developing and manufacturing of ATM Turbo 2 along with bugfixes. 6.25 (or 6.2A) was eliminated three errors compared to 6.10. In addition, from now not only the expensive AY-3-8912 but also the cheaper AY-3-8910 audio chip can be used. There are only two faults left on the 6.30, that can be fixed with three wires and do not require the 555TM2 modding. In 6.40, previous errors were corrected, and the keyboard and Sinclair joystick can be used simultaneously. The 64-button keyboard controller unit has been removed from the board, although still supported by an extension card.

The 7.00 version of ATM Turbo 2+ motherboard was born with two bugs. Here, besides XT keyboards, we can now use AT compatible one, which is controlled by the 1816ВЕ31 chip (i8031 compatible). You can switch between the two by replacing the ROM. Memory now can be expanded to 1 megabyte. The modem with its many analog components was replaced by a dedicated ADC chip (561KP2). Reliability of memory and disk management was also improved. On MicroART's 7.10 version were fixed its previous bugs and the connector of the keyboard became more compact, and design of the PCB changed slightly.

The new version of 7.10 (which has been re-released in some incarnation since then) was originally designed by NedoPC group in Moscow in 2004. It was contained both domestic and import parts. This one is the modern version of the previous motherboard, was made according to the standards of 2000s. Also contains minor corrections comparing to the original. Between 2004 and 2006, about 50 pieces were made. There are two revisions, which are not marked separately. About 15 minor changes were applied in the newer. During its development, was aimed to able to connect modern peripherals (keyboard, mouse, hard disk, etc.) to the motherboard. Additionally, the team was continued of developing software too. For example, the TASiS operating system, developed from iS-DOS, has been written in order of using the extra capabilities of ATM.

ATM Turbo 2++ machines were born from version 7.15. Development was taken over by Alexander Korovnikov (Zorel) from Dnipropetrovsk. It was based on version 7.10, its main innovation was doubling the size of RAM, which is in this prototype status was meant of simply doubling of the number of RAM and their controller chips. So, RAM was implemented with 32 pieces of 565RU7 chips in this case.

At version 7.18, there are only two MSM5118160F-JS memory chips (and controllers) instead of 32. So theoretically, we could have 4 megabytes of RAM, but it was left unused. Another innovation is the expansion card with two ZX-Buses, plugged into the Z80 processor slot.

ATM Turbo 3 starts from 8.00. This was based on the previous one, with the design to match the standart 305x244 ATX size. The 4 megabytes RAM is addressed by the scheme of ZX Evolution, so we talk about a intermediate configuration between ATM-Turbo 2+ and ZX Evo (BaseConf). The following novelties have been introduced compared to Turbo 2+. Now you can choose from 4096 colors palette the used 16 ones. FDD controller also supports HD disks. Amplifier works in the same way as in the case of ZX-Evo. It was also received two audio inputs. Thanks to the 27s080 or 27c801 EPROM chips, we can choose from 1 megabyte EPROM, selecting the necessary one with DIP switches. You can even boot ROMs from floppy disk. There are also another new add-ons: integrated Kempston joystick, mouse interface and real-time clock. Unfortunately, the SD controller did not fit onto the motherboard. Version 8.10 is the bugfixed version of the previous one from the end of 2018.

The Z80 processor of all motherboards are running at 3.5 or 7 MHz turbo mode along with a ROM size of 64 to 128K. In case of Turbo 1 and Turbo 2, RAM size can range from 128K to 512K.

Even the Turbo 1 has already offered three graphics modes. First one, of course, is the standart ZX Spectrum screen. Second is the 320x200 EGA-level 16C mode. In this mode, you can select 16 colors for each pixel from the 64-color palette. High-res mode uses 640x200 resolution with 1x8 attribute grid, so we are talking about hardware multicolor - although with non-standard ZX Spectrum resolution, again it is much more EGA-like one. The picture is obtained via a SECAM decoder on a TV set or by monitor.

Mass storage device can be a cassette beside of the Beta-128.

Among the beeper, AY-3-8912 and Covox can be chosen as for sound. The analog-to-Digital Converter is capable of sampling up to 9KHz in a single channel. The modem is based on the D/A converter.

The built-in 48K/128K BASIC firmware was enhanced with a printer controller part. TR-DOS 5.03 version was also expanded. CP/M v2.2 runs on the top of BIOS 1.03 or 1.04.

We also find two Sinclair joy and Centronics connectors.

Compatibility of the first version is about 60%, with some modding the quite adequate between 90% and 95% can be reached.

It includes a 2x1Watt stereo amplifier too.

At ATM Turbo 2, screen modes are expanded with a 80x25 chars, 16-color text mode. As mentioned before, the AY-3-8910 can be used from v6.25.

The version number of CP/M was remained, although now it is running on the 1.06 or 1.07.12 BIOS. Also possible of using the TBIOS operating system.

The Secam decoder was removed, so it does not work with TVs. IDE controller was also been introduced in this version. The still one-channel A/D converter supports the sampling frequency up to 200KHz. Instead of the 64 button keyboard, you can use XT-compatibles here.

The compatibility is about 90% as standart, which can be tuned up to 95-96%.

For Turbo2+, RAM size can be expanded to 1 megabyte, and the bugs of BIOS version 1.07.12 have been fixed. The ADC is now 8-channel, with the same maximum sample frequency as the previous.

Depending on the firmware, can handle AT keyboards beside the XT ones.

It also has an RS-232 serial port, used to connect a (non-Kempston compatible) mouse.

ATM-Turbo 2++ can address memory up to two megabytes. Also features built-in Turbo Sound.

Updated: 2018. December.

ATM Turbo 1 v4.1 by µART and ATM
ATM Turbo 1 v4.50 by µART and ATM
ATM Turbo 2 v6.5A by µART
ATM Turbo 2+ v7.10 by µART
ATM Turbo 2+ v7.10 by NedoPC
ATM Turbo 2++ v7.18
ATM Turbo 3+ v8.00
ATM Turbo 3+ v8.10

ZX Spectrum +3e/+2e Spain Serbia Poland Czech Republic Slovakia Sweden Great Britain Italy

ZX Spectrum +3e is not a completely new machine, but the "enhanced" version of the last official Spectrum, named +3 (must note, that the black +2A and 2B are also can rebuild to +3e, more exactly to +2e, as they have the same mainboard). This machnine is the inventment of Garry Lanchaster from Spain.

Two new modifications were introduced with this machine.

Firstly, the new +3e ROM, and secondly, the possibility of connecting hard disks and Compact Flash cards.

The original +3 ROM was bugfixed, as well extended with new Basic commands. With this, for example, .SNA .Z80 files downloaded from the Internet are directly usable on original Spectrums. These new ROMs are even offered on sale, for owners who are affraiding of the task of burning EPROMs - others can download the ROM image files from the Internet either in English and Spanish language.

Second phase of tune-up is building the IDE interface. In 2000, was a relatively new idea to connect hard drives to the ZX Spectrum. Only Putnik's 8 and 16 bit interfaces were existing. +3e was using the simpler, 8 bit version. Pera's interfaces also will detailed later.

Going through the years, number of IDE interfaces were quickly increased, and this machine also begins to support them. And it is also works fine with Compact Flash cards, which are more popular nowadays.

The Polish Jarek Adamski also get interested in the +3e tuning, and did not wanted to leave out the owners of older machines. That is why he developed the PL3MEM card, which can tune up the 48K/128K/128K+2 and TC2048/2068 machines. Details will come later, Jarek's developments worth a dedicated section.

Until the native support of CF cards was not ready, owners could choose the construction of Jose Leandro Martinez Novellon or Aitor Gomez Garcia from Spain, which will also described later.

One of the members of the hw.speccy.cz team, Ik0n has further developed the original idea as ZX Spectrum +3e^2. Here, with a switch, we can choose between regular +3 and + 3e modes.

At the moment it is compatible with Pera Putnik's 8, 16 bit and CF interfaces, Sami Vehmaa's ZXCF(+), ZXCF+2, ZXMatrix cards, the divIDE(+), MB-02+ and MB-02+IDE interfaces, the ZXMMC and ZXMMC+ expanders as well Jarek's Yamod.IDE8255 controller and certainly with the PL3MEM card, which is contains the previous controller as standard. Philip Mulrane was also integrated it into his ultimate +2A/2B floppy interface.

The success of the concept is indicated by the fact, that its FGPA emulation was also released by Alessandro Dorigatti. He was integrated the ZXMMC+ system into the Turbo Chameleon 64, V6Z80P és MCC-216 'consoles'. After some tuning, the already mentioned Jarek Adamski’s Yamod.ATBUS interface also can simulate its operation by the interface of Pera Putnik.

About these things we will read later.


ZX Spectrum +3s Romania

The ZX Spectrum +3s is a real new development, which is created by the Romanian Cristian Secara (nick: Secarica). Letter 's' is pointing to his nickname. The project was begin in 1989, and some part of it did not finished yet.

Purpose of Secarica was to make such machine, which is compatible with all Spectrums and capable of running CP/M.

Well, the machine is 99% +3 compatible, and has various extras: 14MHz speed, 1024K RAM, 64K vRAM. With shadowing, any Spectrum ROMs can be loaded. Sound source is the AY-3-8910 chip, mass storage units are 2x1.44 megabyte floppies. Picture is sent to RGB, PAL and composite video output. Eight new function keys as well the conventional Kempston joystick port also get the place. The IN#FF video bug found in the original +3 was eliminated, so almost all 48/128K classic games are running fine.

The mainboard was made in three different subversions: first was running at 3,5/7MHz, second is around 3,5/7/11MHz, and the latest is the present. In past times, contained an overlocked 10MHz CPU, nowadays it uses a downclocked 20 MHz one. Unfortunately, the current system will not allow higher speed than approximately 15,5 MHz.

Due to lack of space, two smaller circuits (which were originally the part of the original mainboard design) were realised on separate two smaller boards.

The floppy controller was taken from the Romanian Cobra clone, and the author had to made smaller modifications to work properly with 3,5 HD disks, not only with 5,25 and 8" ones.

The PAL encoder card is an own design. Base resolution is the same of the original machines, but it is offers two another: the hi-res mode and the possibility of switching on and off the horizontal and/or the vertical border. In that case, picture is stretched to the whole screen.

The author is still working about the display improvement of the CP/M mode as well on the final version of real time clock.

Also a problem for the developer to find a suitable case for mounting respecting the size of mainboard. He is still working of connecting submodules, for example building the audio circuit.

On his homepage, some +3 fixes also found, which were used during the development of superclone. The buggy AY sound was fixed along with a stereo tuning. Beeper was separated to the TV speaker, the sound of AY-chip is to two RCAs or sent to the RGB peritel port. In that way DIN cables can used. The already mentioned IN#FF video bug fixing is also on the homepage. He was tinkering composite video output for the +3 and +2A/B too. Basically, it is the circuit of the older 128K/128K+2 machines, which are left out from the last, cost efficient Spectrums. Some hints and tips also found about using and mounting internal 3,5" drives. 180, 720 and 800K disks are useable. Sadly, modern floppy drive units are not compatible, so must hunt for old XT or XT/AT types.

ZX Spectrum +3s 3rd revision

SpeccyBob Great Britain

SpeccyBob name covers two clone prototypes. The normal version (SpeccyBob 2) is an extended clone with extra functions (which are not really extra in the 21. century...). In fact, they are the same as we can found at the modern Spectrums: new video modes, IDE interface, 4 megs of RAM etc. etc.

SpeccyBob Lite is a simple ZX-clone built from contemporary electronics parts. It is only a 48K Spectrum clone, but compatibility at least is 99%. This is not even achieved by Amstrad in the old days... Of course, the second one is much closer to realisation, you could see photos from the working machine.

SpeccyBob consists of three mainboards - so looking quite different from the original Spectrum. The homepage is not accessible for a long time.

SpeccyBob Lite

Chrome Italy

Chrome is the "Italian clone", which was developed in 2004 on the basis of SpeccyBob Lite. Its constructor is Mario Prato, who a decade later created the DivMMC interface as well.

Opposite of its forefather, not only compatible with standard 48K Spectrum, but as well with its 128K brother. It offers various extras, such as the 7MHz turbo mode realized with Z80C processor, and the further introduced +D floppy interface.

By the author's opinion, compatibility reached 99,9%, although some demos do not work perfectly. Size of RAM is 160K, and sound is produced by the usual AY chip in stereo. It has Kempston compatible joystick port and a Centronics interface too. Beside the floppy disk, conventional tape cassettes can used as storage devices. Picture leaded out through a Scart connector. Additionally, a real time clock is also placed on the mainboard.

The machine is consists of 12 chips, and looks very professionally. The developer put it into a self-made black aluminium case.

Maciej Gruszecki, aka pear, was created the Chrome 128 motherboard within the frames of Speccy.pl virtual community. This one is based on the original clone and can be built into the housing of the original ZX Spectrum. The red colour board has three known editions: Issue 3, 3A and 3B.

Updated: 2019.January

Chrome prototype v1
Chrome prototype v2
Chrome prototype v2 mod
Chrome 128K Issue 3
Chrome 128K Issue 3A

ZX Badaloc Italy

Alessandro Poppi’s ZX-Badaloc clone only one (perfectly working) CPLD-based wired prototype exists. Currently, onwards 2008, the project has been running on FGPA basis. Badaloc is "surprisingly fast" in Modena slang, referring to the machine up to 21MHz peak speed. Otherwise the frequency of clock can be varied between 3.5, 7, 14 and 21 MHz in multiple steps. Its basic components three Xilinx CPLDs: the XCR3384XL is the ULA emulator and has two XC9572XLs. One is charge for I/O operations, and the other for the keyboard (PS/2), Kempston compatible mouse (PS/2) and controlling the joystick along with a PIC16F877 microcontroller.

A 20MHz Z84 processor controls the memory chips, the Flashable firmware EP(ROM), the AY-chip (stereofized) and the SD/MMC interface, together with a real-time clock, which one is a Dallas DS 1210/1307 type. By the way, the interface was implemented as a separate project known as ZXMMC card can be up to 32 characters length, the file system is not standardized. Not only ability to read from memory cards, but also from a host PC using UART.

Keyboard controller is capable of handling the conventional 40 keys matrix, so the PS/2 keyboard is not necessary. In case of PC-keyboard, combined key functions are also available. The video circuit of course, was integrated into that CPLD, which emulates the ULA and it is VGA compatible. There are two modes: one is the standard Spectrum, another resolution is 320x256 with 16 colors.

Size of RAM consists from the video memory of the scan-converter (128K) as well the ZX Spectrum memory (128-512K) and the video memory of Spectrum (32K dual-port). Into the ROM slot 27C512 - 27C4001 EPROM (64-512KByte) or FlashROM can be fitted, so 4-32 pieces 16K-ROMs can be stored at the same time. The machine itself able burning the FlashROM.

Sinclair edge connector was managed to build almost to 100% compatibility. At least, the ZX Printer works with it.

A ZX-Badaloc Reloaded is the continuation of previous project, integrated into FPGA circuits instead of CPLD basis. Hence from here comes the alternative, ZX-Badaloc FGPA name. With this solved the main problem, the cable jungle.

Development immediately split into two ways. First was built around a Xilinx Spartan 3E HW-SPAR3E-SK-UNI-G card. Meanwhile, a small, low cost version, based on the Avnet Spartan 3A card was realized as the ZX-Badaloc Nano.

The soul of this subversion is the 3A-400 FPGA. Since the card does not contain either VGA or PS/2 port, so they were implemented on a special mini card. The RS-232 port has been replaced by an USB one. As it does not have considerable RAM, so only able to emulate the 16K Spectrum.

Finally, the two developments was combined onto a Digilent Nexys2 Spartan 3E card, using a XC3S1200E FGPA (it is possible, that Xilinx Spartan XCS500E also be able to manage the project). On the new card, some functions have not been implemented.

They are on a separate board, on the Digilent's "pmod" module were realized, which is containing the cassette, speaker, joystick and SD card interface, as well as the Flash feature. This was drove the LEDs until it was replaced by the OSD. The card would otherwise be able to run the main functions of the clone itself. Has real MIC/EAR jacks and speaker outputs, which can serve the emulated AY-chip (YM2149 core by mikejd). Also though the RCA audio output can be heard both the beeper and the AY-chip. PS/2 keyboard can be also connected to it. It performs serial communication via RS-232 port. Programmable joystick port is provided too. The SD card reader was also remain on it.

This clone is compatible with the ZX Spectrum 48/128/128K+2/128K+2A and +2B/128K+3 machines exception of emulation of lower 16K slow memory. Speed of the processor now also works on 28 and 42MHz with T80 core emulation (FPGA Arcade T80). 8 pieces of 512K RAM in it, for each part belongs the same amount of Flash memory. These are emulated by the RAM, so a wide range of ROMs can be handled by the SPI Flash.

VGA now has 256 colors and the Spectrum mode supports the ULA+ based on Alessandro Dorigatti’s code.

ZX-Badaloc Reloaded on Xilinx Spartan 3E
ZX-Badaloc Nano
ZX-Badaloc Reloaded on Digilent Nexys2 Spartan 3E

ZX Spectrum S2008 Croatia

In 2008 some Croatian ZX Spectrum fans were created the ZX Spectrum S2008: Tomislav Talan, Ivan Siric, Zoran Boskovic, Suad Cokljat, Vlado Banda and Kresimir Slonjsek.

Initially, they wanted to make an additional module for the Spectrum with CF reader and joystick, but the result became a complete, upgraded ZX Spectrum 48K clone. The motherboard was used SMD technology with retaining some of the original components. For example the Z80 and the ULA.

The original machine case has been modified according to the new connectors and the keypad foil is now has wired connection to the system board.

The integrated ZXCF interface uses 1 megabyte of battery backed SRAM with the ResiDOS operating system. It has NMI and reset buttons. With the NMI, programs what copied into the RAM will be retained even after reset and shutdown thanks to the battery.

The joystick interface is Kempston-compatible, the sound is made by an AY 8192 chip, taking out in stereo through a 3.5-pin jack - with adjustable balance, bass and treble.

It also includes a so-called protoboard for future developments and additions. Has also a built-in RS232 interface and a composite out. You can choose from four ROM sets with DIP switches. The first 10 series was made of 5-5 red and green motherboards. The second series also including bug fixes.

By the opinion of the main constructor, Zoran, it is possible to upgrade the machine to 128K with RGB output with the protoboard, but looks like the project has stopped for now.

Added: 2018. September

ZX Spectrum S2008 mainboard
ZX Spectrum S2008

ZX Spectrum 2009 Remake Italy

The ZX Spectrum 2009 Remake Remake is the clone of Gennaro Montedoro from the (very) first day of 2009.

Its main features the low power consumption (360mA), the 100% Spectrum compatibility, and the easy building, which is partly due to the design, which counts 15 ICs less, than the original.

This because the reduction of the number of memory and their controller chips.

It is usable with the original Sinclair power supply. It contains a 'small' tuning facility. As is reality the two 16K DRAMs are 64K ones, so possible to transform to a 128K clone.

Updated: 2012. March

ZX Spectrum 2009 Remake

ZX Spectrum SE (Chloe) Great Britain Poland

The ZX Spectrum SE (codename: Chloe) is a second generation Spectrum clone, which is the development of Andrew Owen (Cheveron/Cheveron Group and Jarek Adamski from 1999. Although only only prototype was made, numerous emulator simulating it.

The SE combines the memory techniques of Times TS2068 and ZX Spectrum 128K and adding further 16K for it. So altogether has 272K RAM. After the modding of Jarek the ZX Spectrum 128K part uses 144K, while the rest 128K SRAM is controlled by the Timex. The standard ROM was replaced to a 64K EPROM. From this only utilizes the machine 32K. First one is the modified 128K editor. Second is the 48K Basic ROM with some TR-DOS add-on.

Added a 8K serial EPROM to the AY-3-8912. Thank to it, Timex and Sinclair modes both supported. Output is switchable ABC/ACB stereo. The beeper sounds is coming from the internal loudspeaker, but muted when loading or saving.

Picture is done by the TC 2048 SCLD circuit instead of the ULA, in which Jarek was bugfixed the snow effect. It has more screen modes. Beside the normal one, supports the 512x192 Hi-res, and the Hi-colour with 8x1 attribute cells. Possible to use the two ones together, for example the top half of the screen is Hi-colour, and the bottom is Hi-res. Can be handful with text adventures. Due to the 27K videoRAM, four normal or two Hi-res or Hi-colour screens can be handled.

Available software is primarily emulators: Acorn BBC B (unfinished), Apple I, Commodore VIC-20, Compukit UK101, Galaksija, Jupiter Ace, Phillips Videopac G7000, Sinclair ZX80, ZX81, ZX Spectrum, ZX Spectrum 128K and Timex Computer TC2068 can be the machine. Also emulates the Interface 2 ROM cartridges and Mikro-Plus cartridges.

Chloe 280SE is the series production ready version. The CPU is Z804C0020 at 3.5MHz or 21MHz, with 256K RAM and 32K videoRAM. In the 32K FlashROM the SE Basic IV is the default operating system. The sound is done by the YM219F of course in stereo. As an extra, supports the ULAplus mode beside the Hi-res and Hi-colour.

Chloe 140SE is a simplified version. Can not able to emulate the Times 20xx machines, as this memory region is missing. Comparing to the previos clone, it has only 128K RAM.

ZX128 Lithuania

ZX128 is a Lithuanian development, which was built on the basis of Leningrad 1 clone. The computer consists of three main elements: the mainboard itself, the video controller and the General Sound card is also could be connected to it.

The speed of processor is 3,5MHz, and the size of memory -as the name suggests- 128K. Above that, it contains 32K SRAM, which is responsible for holding different operating systems. In the 64K ROM placed the ZX128 Commander utility too.

The developer was not spared with various outputs. So picture can lead out either by Super VHS or RCA ports. Stereo music made by the Yamaha 2147F chip is ported to two RCAs and a stereo jack. The mainboard was also equipped with Kempston, Sinclair 1 and 2 compatible joystick ports.

The real innovation is presenting of USB port. With this, we can use Flash cards as storage devices.

Unfortunately no more news since August of 2007.

Updated: 2019. March


ZXGate Germany

ZXGate project was started on the basis of Bodo Wenzels' ZX97 machine, which is a ZX81 clone. But in this case, the whole ZX81 is integrated into a single FGPA chip. Beside this, it contains three another classic computers as Jupiter Ace, TRS-80 as well ZX Spectrum.

The ZX Spectrum ROM did not get place in the machine, must be loaded separately into the 32K SRAM. All of 48K functions are integrated into the machine. Of course, the author cannot promise 100% compatibility, because impossible to test it with all programmes. The machine has output for monochrome and colour monitors as well has a Super VHS port.

Speccy 20xx Ukraine Russia

Speccy 2007 was originally a 48K clone built around the Altera EPM7128SLC84-15 programmable logic circuit and the ATMega16 controller. Thus, the cost of producing the complete motherboard could remain below $50. Unfortunately - as we used to say - the compatibility of the machine is far from the perfect. By the oppinion of Peter Kitsun (also known as Syd), who lives in Kiev, not necessary to build another ZX power plant, for that, there is for example the Pentagon 1024SL. His aim was to create a basic, original Spectrum with the help of today's available parts. You can connect PS/2 keyboard to the machine. The picture outputted to monitor and sound via RCA connector.

The first version of the machine (Speccy 2007 v1.00) was released in December of 2007. With this machine the .TAP, .TZX and .SNA files downloaded from the Internet, can be load from an SD card up to four times faster. Nevertheless, thanks to press of the zx.pk.ru forum, Syd was improved the machine together with the members of the community. Speccy 2007 v1.04 came out in March 2008, which already had TR-DOS support.

The next stage of development is associated with molodcov_alex (Aleksandr Molodcov). According to his plans, Speccy2007 v2.00 (Speccy2009) would work with the Z80 and 128K (Pentagon compatible) RAM built around the Altera EPM3256. The ATMega64 controller would be responsible for VG93 emulation and controlling of keyboard and mouse. The pictue would be scaled up to VGA output. Kempston joy connector and ZX Bus were also designed on the motherboard.

Based on this idea, in April 2009, the 2007 v1.06 was released. This machine was already worked in the 128K+AY+TR-DOS setup, according to the above concepts. The controller finally became ATMega32, its capacity proved to be enough for 128K emulation, but the AY part was still on a separate card. Can already handle SD cards with larger capacity than 2 GB.

This was further upgraded from St. Petersburg in May 2010. Ljubitel’s Speccy 2007 v1.1 has already integrated the AY/YM chip onto the motherboard.

In the zx.pk.ru forum, in March of 2010 Elker was announced the revision 0 of the Speccy 2007+128K+AY motherboard, which had already contained the integrated PAL encoder circuit and the sound was also taken out by two RCAs. This was followed in the same month (?) by the Speccy 2007+128K+AY rev. 2010, with a professional PCB. According to the inscription on the motherboard, the exact name of machine is Speccy 2007/2-128 v1.0. In February 2012, Speccy2007+128K+AY rev.2012, .ie Speccy 2007/2-128 v1.2, was released with a firmware update.

After a long break, on April 1 of 2016, .jackson was announced the Speccy 2007 128K+AY+TR-DOS (Speccy 2007 128K CMF) combo. Here, the single RAM memory was made by using of an old machine’s cache memory chip (the original design contains two chips). Its last firmware version is 1.06.

The Speccy 2010 is a clone created by using the Altera Cyclone II FPGA (EP2C8Q208C8N) and the STMicroelectronics ARM7 (STR750FV2T6 or STR750FV2T6) CPU. It was inherited the the dimensions and main features of the Speccy 2007.

Virtually we can create a variety of configurations, as standard, ZX Spectrum 48/128K and Pentagon 128/1024K modes are selectable.

There is an SD/MMC card slot on it. The real-time clock type is Dallas DS1338Z-33 +, in this case emulates the Gluk RTC.

There are two PS/2 ports (keyboard and mouse), 2 joy connectors and an optional USB. The mouse is Kempston compatible, and the joystick can be various standard.

In case of video outputs, we can choose among RGB, Composite, S-Video or VGA images created by 3 R-2R DA converters.

Audio production is the task of a TDA1543 or double R-2R. The (stereo) AY/YM modes, the TurboSound and of course the Beeper are supported.

Despite being perfectly compatible with Speccy2007 v1.06, it also has several new features. For example, 1 megabytes of available memory (Pentagon 1024K emulation). Turbo speed can also be adjusted in several steps: 7, 14 or 28 MHz.

Among the members of zx.pk.ru forum, Sabirzhanov Vadim Mirzhanovich (zst) undertook the task of "mass production" of Speccy 20xx series. Speccy 2007 had the ZXkit-002 name, the 2010 version has been released as a ZXkit-005 in his webshop. A ZXkit-004 was also available, it is an 128K Expander and integrated AY circuit for Speccy 2007. With this expansion, can be achieved the memory upgrade and stereo 3-channel music. Despite of its name, it uses the YM chip. The new webshop is offering only Speccy 2010.

Updated: 2018. September

Speccy 2007 v1.00
Speccy 2007 v1.06
Speccy 2007 v1.1
Speccy 2007+128K+AY rev.0
Speccy 2007/2-128
Speccy 2007+128K+AY+TR-DOS
Speccy 2010 rev 2

ReSpecT 48K, ReSpecT-2 (128K).

ReSpecT clone will made on the basis of SpeccyBob project. As its forebear, it has got two variants: ReSpecT 48K and ReSpecT-2 (128K). These clones are the prototypes of Z.A.N. from Russia.

First version simulates a basic 48K Spectrum with again a help of Altera EPM7128SLC84-15 circuit.

Second one offers numerous innovations such as new graphics modes: 256x224, 256x256 and 320x200 with 16 colours. Upcoming novelty in Spectrum terms the 4096 colours palette. From that, we can display 16 colours at the same time on the screen. So it is possible to realise more natural pictures. Beside this, the already mentioned Pentagon 1024SL v2.x's colour -per-pixel mode will also supported. In addition, author is planning to produce the 21 MHz high-speed version.


Neo v1.0

ILoveSpeccy's project is the Neo, which is based on a Xilinx Spartan XC3S400 programmable logical circuit and an ATMega 644 microcontroller. Equipped also with 3 pieces of 512K SRAM module and a SD-card slot.

Its most interesting special feature, that all units of mainboard can be reprogrammed without opening the housing via the USB port. This ensuring limitless possibilities for developing of different configurations.

The following peripherals are supported: VGA output with color-per-pixel ad 4096 colour mode, PS2 mouse and keyboard ports, stereo jack, tape, RS-232C and joystick ports.

The PCB is one-sided, prepared at home by the author, therefore the computer can be easily repeated.


FPGA Speccy United States

Alex Freed's FPGA Speccy project was released after the author's Apple II and Elektronika BK0010 (a Russian clone) machines. After successfully making two relatively rare retro replica clone around the Xilinx Spartan3 circuit, the time has come to create a new ZX Spectrum.

The machine is still under development, and not only able to run at 3,5MHz, but has a turbo mode also with 28MHz at the moment, but by the testing programs it will run at 56MHz. So welcome a new speed champion among the ZX clones!

Video output of the newcomer is VGA, because it has much more nice screen comparing to an ordinary TV set. Next stair of development is an IDE interface, in order to read the programs from CF cards. At the moment, .TAP files are loaded from sound card, which is good, but damn slooow.

A 256K EEPROM contains the ROM routines of the 128K Spectrum, which loads into the internal memory (BRAM) of the FPGA at the booting process.

FPGA Speccy


The under development Ant-1024HD clone based on KAY 1024 as it was denoted before. Like another Russian clones, it also uses the Altera EPM7128SLC84-15 circuit.

The clone contains Kempston joystick, keyboard, monitor printer and magnetofon ports. From the HD name seems, that hard disk can also connected to the machine, so on mainboard you can find an IDE controller. This can control the CD-ROM as well.

The VHS cassette sized mainboard will be compatible with DMA Utra Sound Card. Certainly has 1024K RAM and supports the 7 MHz turbo mode.

Pentevo, Pentevo Light (Pentagon Evolution, ZX Evo, ZX Evolution) Russia

The Pentevo (=Pentagon Evolution) clone was created in 2009 by the NedoPC group in 2009. The name of its authors: Vadim Akimov (LVD), Chunin Roman (CHRV) and Dmitry Dmitruiev (DDp). The motherboard was introduced on Chaos Constructions 2009. Beside the ZX Evo name, also known as ZX Evolution.

It has three subversions as: Revision A, B and C.

The first machine was built around the Altera EP1K50 FGPA controller and peripherals controlled by the ATMEGA 128. The DIP Z840008PSC processor can be run on 3,5 or 7 MHz speeds. The machine contains 4 megabytes of RAM and 512K ROM and equipped with two ZX Buses.

The keyboard and mouse attached through PS/2 ports. It contains a Beta-128 controller, a single channel IDE, SD-card reader as well tape socket. The picture output either can be RGB or VGA. The usual real time clock is also present as well the support of original keyboard and joystick.

The Revision B contains some corrections, and the size of mainboard became smaller and its quality was improved. The 20MHz DIP Z84C0020PEC has the 14MHz running option.

With Revision C, the mainboard changed from ATX to ITX standard, and only the VGA remains as picture output. It also got an USB output. The speed of the QFP mounted Z84C0020FEC remained the same. With firmware update it can be compatible with ULA+.

The creator of ZXM-Phoenix series, Mick in 2011 July made the Pentevo Light motherboard. His main purpose was to studying the FGPA programming in VHDL and Verilog languages.

Some cosmetic changes were also made on the revision 01 mainboard. The RGB out was again removed, leaving the VGA the only screen plug.

Ewgeny 7 was made a new ROM, with which the machine will be Scorpion ZS256 Turbo+ compatible.

TS-Labs has also developed an extension, called ZXEVO TS (TS-Conf(ig), TS-Configuration). >Here the support of new video modes and sprite management are the major novelties, but memory and processor management remains fully compatible.

In addition to the standard ZX Spectrum resolution, there are some another are available: 320x200 resolution in 16c, 320x240 with 256c, and text mode with 360x288 pixels.

Updated: 2018. May

Technical specifications
CPU: Z84@3.5/7MHz (rev A), Z84@3.5/7/14MHz (rev B, C)
ROM: 512K
Sound: AY, beeper, Covox
Keyboard: PS/2, standart 8x5 matrix
Joystick: Kempston
Mouse: Kempston
FDD: Beta-128
HDD: Nemo
others: MIC/EAR, RS232, USB, VGA, (RGB), ULA+

Pentevo rev A
Pentevo rev B
Pentevo rev C
Pentevo Light

ZXM-777 Russia

The ZXM-777 is connected to Mick (Mikhail Tarasov)

The machine was built in the spirit of ZX-777 and KAY-256, of which machines centre was the ATF16V8PAL circuit.

Its innovation was the usage of SRAM modules, so can be born the first own-developed machine of Mick (revision 01).

The turbo mode f machine is 7 MHZ, but not only the CPU, but the memory is also accelerated (by the way, it is the 'fast' cache memory of 386/486 era). The mainboard is AT standard. Between 2006 and 2008 two boards were made from revision 01. This was followed by the revision 02 with some minor modifications.

The project was cancelled, as Mick gained the necessary practice for further developments.
Technical specifications
CPU: TMPZ84C00-8, 3.5/7MHz
ROM: 64K
Sound: YM2149F, beeper
Keyboard: standart 8x5 matrix
Joystick: Kempston
others: MIC/EAR

Added: 2010. december 12.

ZXM-777 rev 01

ZXM-Phoenix, ZXM-Phoenix 2 Russia

The ZXM-Phoenix clone is the development of Mick (Mikhail Tarasov). The idea of realization was appeared in the end of 2008 on the zx.pk.ru forum.

The inspiration was based on, that members desired to wanted to remind to their youth. On the another hand, Mick liked to trying out himself in a whole project development.

Development was begin in late 2008, with revision 00. Unfortunately users discovered a bug on the green mainboard, from which 6 pieces were made. By the way, it was targeted to realize without FGPA to bring the look and feel of 90's. The board which contains 71 chips, is controlled by the ATMega 8515 microcontroller. Also integrated on the board Caro's ZX Multi Card controller.

The bugfixed first revision (01) was appeared in May 2009. and made 65 pieces of them again in green.

In 2010, due to the request of members, Andrew Charles (CodeMaster) was produced a new series of 15 boards in China, with blue PCB in that case (revision 02).

In the next year, from the 03 revision mainboard again produced 31 pieces and again in China. The development was co-ordinated by Anatoly Gajvoronsky (Zorel). The new mainboard was integrated the SD-Card controller, the new development of Vitaly Rudegenko (Keeper). Number of chips were raised to 72. Manufacturing was arranged by Dmitry Demyanekenko (ZEK). This board is red colour.

As most fans also wanted a turbo mode, Mick fulfilled their desire. It was created on the base of the turbo mode of ZXM-777. In that way, was born the black coloured 04 revision number mainboard with 74 chips. Location of manufacturing again China, and the number of plates is 16.

In 2012 was constructed the final edition, the revision number 05. In it was realized the 128K lock-up mode, which prevented the problem, when using some 128K only software. With the ATiny 13 micro-controller the power management also solved (the 12, 15 and 45 types also can be used). The number of chips again reduced to 72. The 15 pieces of mainboard set was again made in China.

In the same year, after some bugfixes Zorel was decided another to made another 17 pieces. The board got the 05.1 revision number. The colour went to red again, and again was manufactured in China. The making of the last 21 pieces was done by Vitaly Mikhalkov (MV1971) from 2013.

Worth to note, that in late 2012 released revision 06. But it not became 'official', as it not compatible with the others. Its case, that Mick tried to made Pentagon compatible the video timing.

So the last official version is 05.2, not the yellow sixth, which was made in 15 pieces.

The ZXM-Phoenix 2 clone was born from the modernization of its predecessor from 2010. It was crammed into CPLDs the most important functions (EPM7032 and EPM7064) Memory expanded to 4096KB with SIMM72 modules.

This machine is not only KAY and Scorpion compatible, but also has Pentagon mode.

Some new graphics modes also were introduced. For example the 15 or 16 colours already well-known modes and GigaScreen. The most important is the 15 or 16 colours from 128 colours palette and the 15 or 16 colours Border modes.

The 7MHZ turbo mode is standard (memory runs constantly in turbo mode) just like the VGA output.

In the development, more great Spectrum enthusiast took part also.

Kamil Karimov (Caro)was helped to integrate the previously mentioned controller card. Tkacuku Valeriju (Black_Cat) was give help to create the audio mixer. Eugene Ivanov (Ewgeny7) take advices how to handle the extended memory. Rudenkomu Vitaly (Keeper) was provided a modificated floppy controller design and a lot of firmwares. Gerasimchuk Sergei (Zloy) took part in the implementation of the Scart interface. Stanislav Yudin (CityAceE) collected the old and new Spectrum fans on the forum. Andrew Shapovalov (Xobbiman) hosted the webspace for the project, until Mick does not made his own webpage. Dmitry Demyanenko (ZEK) designed the circuit of SD card controller.
Tech specs (ZXM-Phoenix)
CPU: KR1858VM1, 3.5MHz; TMPZ84C00, 3,5/7MHz (from rev03)
RAM: 1024-2048K SIMM
ROM: 64K
Video: 256x192, 15colors
Sound: YM2149F, beeper
Keyboard: PS/2 (emulated)
Joystick: Kempston (emulated)
FDD: Beta-128
others: Nemo IDE, RTC, RS-232, MIC/EAR, ZX-BUS, ZC SD-Card Interface (from rev 03)
Tech specs (ZXM-Phoenix 2)
CPU: Z84B00, 3,5/7MHz
RAM: 4096K SIMM 72
ROM: 64K
Video: 256x192, 15 and 16 colors on 8x1 or 8x8, 15 or 16 colors from 128 colors palette, border 8 or 16 colors, Gigascreen
Sound: YM2149F, beeper
Keyboard: PS/2 (emulated)
Joystick: Kempston (emulated)
Mouse: Kempston (emulated)
FDD: Beta-128
others: Nemo IDE, RTC, RS-232, MIC/EAR, ZX-BUS

Updated: 2015. December

ZXM-Phoenix revision 00
ZXM-Phoenix revision 01
ZXM-Phoenix revision 02
ZXM-Phoenix revision 03
ZXM-Phoenix revision 04
ZXM-Phoenix revision 05
ZXM-Phoenix revision 05.1
ZXM-Phoenix revision 06
ZXM-Phoenix 2

ZXM-Zephyr Russia

Development of the ZXM-Zephyr was begin in the end of 2013, as the carrying-on of ZXM-Phoenix. project. While the phoenix recalled the retro age with its circuits, Mick was built the zephyr around the modern FGPA-basics. But in some aspects it is also retro, because the FLEX 8000 which was belongs to the Altera EPF88220A family, not manufactured already, so remained stocks was used.

Creating the clone has two main reasons. First is to implement the ZXM-Phoenix into an FGPA in VHDL language. Second in to integrate the SAA1099 chip into a mainboard. So with the YM-chip altogether, the music is 9 channels.

The memory of the machine is 512 or 1024K with two static RAM modules. The ROM is the 512K AM29F040 FlashROM.

There is an IDE interface and Caro's ZX Multi Card interface was integrated, which is also the part of the phoenix. Of course, it has USB interface. As the machine is totally freely configurable except from a few parts, it is more like a development board, than a dedicated computer. But Mick was 'developed' a ZX Spectrum clone from it.

Altogether 15 pieces were made from the revision 00 and 01 boards.
Technikai specifikációk
CPU: TMPZ84C00-8, 3.5/7MHz
RAM: 512/1024K SRAM
ROM: 512K FlashROM
Sound: YM2149F, SAA1099, beeper
Keyboard: PS/2
Joystick: Kempston
Mouse: Kempston
FDD: Beta-128
others: SD-Card, USB, RTC, RS232,MIC/EAR, VGA, ZX-Bus

Added: 2014. December 07.

ZXM-Zephyr rev 00

Harlequin Great Britain Spain Germany Czech Republic

The history of Harlequin clone goes back to the beginning of 2007. Chris Smith, an ex-ZX Spectrum programmer found an EPROM burner and a plan of implementing a video circuit board. Then a question arises: how complicated would be to build a ZX Spectrum clone exclusively from discrete circuits?

Goals were set here: 100% compatibility, RGB TV and VGA output, and the ability of upgrade to 128K. Development was started with the detailed study of Spectrum screen’s creation. As a result, the prototype of horizontal display circuit was completed by the end of March 2007.

After lot of experiments, the memory to screen interface prototype was also created in a month. As for test, after trying four game loading screens, it was completely sharp, only a slight noise was visible on the border of bright and dark images.

After the bug fixes, was begin of adding the Z80, RAM and ROM to the system. The card, which was containing them, has been connected to the previous one by an IDE cable. From the beginning of May to the end of May, succeed to create a flawless system.

Then was started of implementing the four I/O subsystems: the keyboard, loudspeaker, the mic and ear connectors.

When they were done, fixing of memory timings and implementing the Flash attribute was begun. Finally, was born the wired Harlequin prototype on a verocard.

This was raised new aims. On the one hand, simplify the discrete logic circuit where it is possible and further improving of timing and stability.

The PCB design was the next task, maybe worth coupled with FGPA or CPLD implementation. Plans included of widening the offered modes: 128K and SE compatibility as well as TS 2068 screen mode implementation. Of course, he was see necessary to document the entire ULA decoding, and a book was also published about it. Was also important to further improve timings and stability, the rest of the blog is about it.

The CPLD-based ULA replacement prototype was released at that time, which was built around the Xilinx CPLD XC95144XL. After its construction, the usual debugging, testing and bugfix was followed, and then the wired unit was replaced by the PCB one insertable into the original ULA socket. Finally, the tests were showed full 48K ULA compatibility.

Superfo’s Harlequin (48K) clone is based on the prototype of Chris Smith. Of course, in its technical features is identical to the original ZX Spectrum, only the video output was changed. This is RGB as standart but with the AD 724 circuit built in, PAL and NTSC composite signals can obtained. By the way, SuperFo (Watchara Chantang) is originally a Taiwanese person.

The first four editions before Revision E were buggy. With the help of José Leandro Novellan Martinez, was able to create the error-free Revision E in 2012.

At the next Revision F, Ingo Truppel was also helped in 2014. Revision G is the last "official" version from 2015, in which Ingo was also helped.

Tomas Kolenak, alias Tomeco was hacked it, so was made the Revision H. His original purpose was to make RGB output for the Spectrum. Then he found the documentations of the Revision G motherboard. The original project was made in OrCAD, but Tomas converted it to Altium. This was immediately showed the mechanical collisions in the 3D model.

His goals included of eliminating these, changing the power supply polarity (positive in the middle - with polarity protection), halving the motherboard size by using SMD components, reducing power consumption and using rewritable EEPROM.

Some mechanical imperfections still occur on the board, but the biggest problem was that it did not display picture. This was solved by replacing a capacitor (it was accidentally smaller capacity than in the original project). Then, on both the RGB and RF outputs got picture.

The Superfo Harlequin 128K is a new version based on the original Superfo project. Features including 32K ROM, 128K RAM, AY-3-8912 chip and Kempston joystick port. It matches the size dimensions of the 48K motherboard.

Further changes are the reset button; as well as the functions of MIC and EAR connectors have also changed. In the pinout of MIC connector became stereo output and the originally EAR now is a combined EAR/MIC out, also using stereo jack.

Its first versions are much more like a 48K machine expanded to 128K than a real ZX Spectrum 128K, for example, its timing is the same. Of course, it is possible to modify the machine to a true 128K, for which documents are available.

From Issue 2D, this modding is already integrated, so timing is 128K compatible. Supports 128K, 128K + 2, 128K + 2A/+2B/+3 and +3E ROMs. These can be burnt into EPROM 29F040 with 8x64K assignment.

In addition, features of Issue 2G including both 48K and 128K timings selectable with a switch, either 27C256 and 27C512 EPROMs can be used.

Updated: 2018. August

Horizontal Display prototype circuit
Memory to Screen Interface prototype circuit
Harlequin prototype
ULA Replacement prototype
ULA Replacement
Harlequin Rev. A
Harlequin Rev. D
Harlequin Rev. G
Harlequin Rev. H
Harlequin 128K Issue 1
Harlequin 128K Issue 1B
Harlequin 128K Issue 2B
Harlequin 128K Issue 2D
128K Adapter for Harlequin Rev A

ZX Omni 128HQ Croatia

The Croatian RetroRadionic enterprise of Djordje Mitic (who was born in Belgrade, and currently living in China) is dealing with modern ZX Spectrum clone replicas and ZX accessories.

Their own development, the ZX Omni 128HQ is available in two versions. "Desktop" is fit into the any of colored 48K case; the laptop is equipped with a 9-inch LCD screen and available as black only.

The machine is based on Harlequin Superfo 128K. Thus, has 128K RAM and 100% ZX128 compatibility. Contains an integrated divMMC interface with dual SD card slot. The standard outputs are the twin joy ports (Kempston or Cursor compatible), RGB and composite out. HDMI is optional. Fortunately, the power and reset buttons missing from original Spectrums, were also present in the machine. Without FGPA, it is built exclusively from discrete elements and the ULA is simulated by SLAM 128.

There are eight ROMs in it: SE, 48K, 128K, 128 + 2e, EXSDOS, UnoDOS, Jupiter Ace and ZX81. With DIP switches can we select between them.

Added: 2018. August

ZX Omni Desktop 128HQ
ZX Omni Laptop 128HQ

ZX Spectrum 128K Remake Great Britain

Jim Askey, the founder of MyPinball Electronics, was meet with the ZX Spectrum at the age of eight, which was introduced him into the world of software and hardware design.

During the repair of 8-bit pinballs and making replacement circuits for them, the idea of creating a 128K compatible motherboard was arosed in his mind in 2016. This became the ZX Spectrum 128K Remake.

The completed board features full 128K compatibility along with lower power consumption and less chip usage compared to the original. In addition, its main features including the RGB image output via Scart connector, built-in IDE and Kempston joystick interfaces, a reset button, Mic and Ear connectors. The machine uses Andrew Owen's Plus 2C ROM.

It was accomplished without the use of SMD components, and fully assembled and tested in the United Kingdom.

Added: 2018. August

ZX Spectrum 128K Remake v0.5

Karabas Russia

The Karabas-128 clone is yet an another 128K clone from Andy Karpov. This time the machine is built around a Z80 CPU and an Altera EPM7128STC100 CPLD and can also be installed into the 48K case.

Purpose of the development was to realize a clone built from minimal counts of parts. The main component is the CPLD, which integrates the ULA, and it is based on syd’s Speccy 2007 clone along with .jackson’s single RAM IC modding.

The AC/DC circuit, the cassette unit interface and the PAL circuit was realized on the base of Harlequin Revision G. Its timing is fully Pentagon compatible.

Added: 2018. August

Karabas 128K prototype
Karabas 128K Rev. A
Karabas 128K Rev. B
Karabas 128K Rev. B1

ZX Spectrum Issue 7 The Netherlands

On Rodney Knaap's Sinclair Hardware Projects page can be found the idea of realizing the ZX Spectrum Issue 7 clone.

The purpose of mainboard (from which only the empty PCB is ready since years) to fit inside an original Spectrum, mainly for for those, who wants to revitalize a dead Spectrum.

For the design, used only DIP chips, without any super-integrated circuits. So an average hobbyist also can reproduce his own Issue 7 Spectrum.

Video output is standard VGA, so the original TV output must have be widened. Who are afraid to do that, of course can use a separate cable.

The pinouts of edge connector also do not the same as the original as it follows directly the pinout of Z80 CPU. In that way was more easier the construction of the PCB and also saved some money this method.

Anyway, the pinout is the same, as on the Micro-ZX81 clone. Rodney choose this because of some kind of 'standardization'. So using conventional Sinclair peripherals must be attached a converting PCB or use the rewiring method.

The connecting ports of keyboard also in different position comparing to original, again because of more simple finalization of PCB.

Unfortunately no news since 2006. September 25.

There are also advices on the homepage for repairing the connecting points of the Spectrum's folie membrane.

And introduced the idea of ZX Keybus Interface too. The basic idea of this to replacing the original processor of the PC keyboard to a simple scanning circuit. The signals of that is converted by the Matrix EPROM, which is connected to the Spectrum. Then the Z80 CPU interprets the signals, as they would come from an original Spectrum.

Added: 2010. May 15.

ZX Spectrum Issue 7 PCB

Sparky eZX

eZ80 board

Sparky eZX project is attached to the American Richard Kelson, who became dependant with a Timex-Sinclair 2068.

The machine was built around the 50MHz eZ80 processor, which is a steroid pumped Z80 mostly embedded into webservers.

The author is making the operating system also by himself.

Keyboard will connected via a serial port. Modem and SVGA ports will also integrated. The CPU can address 16 megabytes directly without any tricks.

The constructor not only intended to be the most powerful ZX Spectrum clone, but also the strongest 8 bit micro. In memory, ZX Badaloc FGPA surely overdrives it, and soon Alex Freed's machine will be also faster... so time to hurry!

ZX Spectrum on Altera DE1

Great Britain

ZX Spectrum on Altera DE1

The idea of the FGPA-based ZX Spectrum on Altera DE1 clone was first announced on the DesignSpark electrical developing community by Mike Stirling .

The project contained two main aims. First of all, to create a working clone, second, to document and publish the results.

Some years ago Mike already made a similar project. He was implemented the functions of the ULA into the Altera MAX7000 CPLD. There were no resources left to realize the functions of keyboard. So, the project was "useless', but at least the machine was booted.

On early 2010 decided to realize a similar thing on the Altera DE1 developing kit. The result is the full implement of ULA, Z80 commands, ROM as well the 8x5 keyboard matrix into the card. Outputs are VGA, TV-RGB, PS/2 as well standard Spectrum Ear jack. Programs can be loaded through that, support of SD cards under development.

The system simulates the 48K PAL Spectrum, but 128K version also can be expected.
Technical specifications
CPU: Z80 (emulated)
RAM: 48K (128K under development)
ROM: 16K
Sound: beeper
Keyboard: standart 8x5 matrix, PS/2
Joystick: none(?)
FDD: none
others: MIC/EAR, VGA, TV-RGB

Added: 2010. november 27.

ZX Spectrum on FGPA with 17 inch LCD screen Slovakia

The clone of Michal Demin, the ZX Spectrum on FGPA (with 17 inch LCD screen) was born by a perky idea, Michal found an old ZX Spectrum in the basement, and nostalgic waves came into his mind.

He was searched for the topics, and the ZXGate project caught his attention. Meanwhile arrived a 17 col 1024x768 pixels resolution old notebook screen. The idea was born: a XZ Spectrum with LCD screen.

The basis became the Sparkfun Spartan 3 Breakout FGPA card. It got 2x32K SRAM.

The I/O card is based on the ZXGate's I/O board, but Michal added the speaker and the NMI button.

The 'last' card is the LVDS transmitter. This is sending the data to the screen. The 256x192 resolution screen is magnified to 4x with eliminating the border.

The Speccy ROM is placed into the FGPA's internal memory.

Added: 2011. February

ZX Spectrum on FGPA with 17 inch LCD screen

ZX Spectrum on FGPA with 17 inch LCD screen


ZX Spectrum on FGPA with 17 inch LCD screen

The clone of Michal Demin, the ZX Spectrum on FGPA with 17 inch LCD screen was born by a perky idea, Michal found an old ZX Spectrum in the basement, and nostalgic waves came into his mind.

He was searched for the topics, and the ZXGate project caught his attention. Meanwhile arrived a 17 col 1024x768 pixels resolution old notebook screen. The idea was born: a XZ Spectrum with LCD screen.

The basis became the Sparkfun Spartan 3 Breakout FGPA card. It got 2x32K SRAM.

The I/O card is based on the ZXGate's I*/O borad, but Michal added the speaker and the NMI button.

The 'last' card is the LVDS transmitter. This is sending the data to the screen. The 256x192 resolution screen is magnified to 4x with eliminating the border.

The Speccy ROM is placed into the FGPA's internal memory.
Technical specifications
CPU: Z80 (emulated)
RAM: 64K (48K used)
ROM: 16K
Sound: beeper
Keyboard: PS/2
Joystick: none(?)
FDD: none
others: MIC/EAR, TV-RGB, NMI

Added: 2011. February 12.

128Ke Great Britain

All 128K Spectrums have hardware bugs and compatibility problems. The 128Ke would be the ideal 128K Spectrum, based on the 128K+2A. The processor is running at 3.54 and memory timings are also 48K compatible. So basically it is a 48K machine upgraded to 128K, reverse engineered from the 128K+A. The project is coordinated by Andrew Owen. Among the proposed upgrades there are Interface 2 support based on Paul Farrow's circuit, Secara's IN #FF video port bugfix, Alistair Fixing the sound on the Spectrum +2A/+3 hardver patch (which is unnecessary with +2B), as well the Atari compatible joystick and audio in socket.

The 128Ke consists only two ROMs by default. First one is the UK128 Editor, the second is the 48K ROM. This is achieved with the method, that in both ROM sockets are installed the same EPROMs. It is because of improve the compatibility, but we can say goodbye to Keypad. Although its functions are still available from the keyboard. Thanks to Alistair's Flash Rom Replacement for the ZX Spectrum +2A/+3, +2B, and +3B add-on, can be used 2x2 ROM sets, activating the necessary one with a switch. Owen was made some ROM collections, which can be downloaded from Alistair's website.

The handling of AY-chip is also done by the way of the regular 128K machine.
Technical specifications
CPU: Z80A@3.54MHz
RAM: 128K
ROM: 32/64K
Sound: AY, beeper
Keyboard: original
Joystick: Atari compatible
FDD: none

Updated: 2015. July.

Fully integrated ZX Spectrum+ Czech Republic

Pavel Urbancik (willcz), who lives in Brno, shows us, how is fully integrated ZX Spectum+ is looks like mostly using Czech/Slovakian developments.

The mass storage device is a DivIDE with an inexpensive CF adapter. The 128K and AY expansion was based on the recipe of hw.speccy.cz. The latter uses the Simple AY Interface Nice Board designed by himself. It also features his another own development, the Sinclair Serial InterFace (Sinclair SIF) for WiFi connection. In the box, a scandoubler (PAL-VGA converter) works on imaging instead of ULA.

The machine operates with 5V after some conversion, so there is no heating problem. Thus, instead of the original power supply, the power is provided by an old router’s one.

Updated: 2019. April

Fully integrated ZX Spectrum+

Leningrad-3, Leningrad-2010, Leningrad-2012 Russia
Leningrad 2010 48K

The story of Leningrad 48K (alias Leningrad -1, Lenin), goes back to 1987. The mainboard, which is designed by Sergey Zonov, was the most easibily manufacturable clone. Thanks to that, it became the base of numerous 'home-brew' and 'brand' machines, despite the fact, that it only contained a Kempston Joystick port as a development. It had 64K RAM, from which the system used only 48K. Some examples for the clones utilizing this mainboard: Spectrum 48 , Ural-48K , IR-30 West , Audio CD-005 , Kontact , CICH-48 , Sunkar.

In 1988, the Composite company developed further the mainboard with Leningrad+ name, which was used in the similarly named Composite clone.

Later, Zonov developed a more easily mass-producable model named to Leningrad-2, which already contained the expansion slot and the connector of contemporary peripherals.

In the Internet-era, more people was reanimated this machine.

Ivan, one of the active member of zx.pk.ru forum, was begin to re-develop his mainboard in the spring of 2007 based on Leningrad-2. After 2 bugfixes and integrating a Scart-socket and ZX-Bus, the creature was christened to Leningrad-3 and finished to green colour in 2007. December 12. The 48K base model is expandable to 128K or 512K with a separate board.

Zst (Sabirzhanov Vadim Mirzhanovich) was made with Leningrad-2010 name his own clone, which got the ZXKit-18 name among his own things. This is mainly repeating the old mainboard with some bugfixes. During the re-design, he was take attention for the more easy future mass-production also. The most important novelty of the blue mainboard is the Flash-chip instead of ROM, and the SCART socket. Release date: 2011. July 17.

In the same year, in November 19. he came out with an improved model, called Leningrad-2012 (ZXKit-020). It has separate Spectrum and Pentagon mode, so handles better the old games. With the Flash-ROM it is ready to support OpenSE Basic and ULAPlus, as well ZX-Bus is standard. This also has the already standard Scart-socket, as well got separate TV and audio out and a printer port.

The aim of the developer was to create a clone close to the original Spectrum. The 1 megabyte RAM FGPA-monsters did not care him too much.
Technical specifications (Leningrad-3)
CPU: Z80
RAM: 64K (48K használt)
ROM: 16K
Sound: beeper
Keyboard: 40 key matrix
Joystick: Kempston
FDD: none
others: MIC/EAR, Scart(?), ZX Bus
Technical specifications (Leningrad 2012)
CPU: Z80
RAM: 64K (48K használt)
ROM: 16K
Sound: beeper
Keyboard: 40 key matrix, PS/2
Joystick: Kempston, Sinclair
FDD: none
others: Flash-ROM, MIC/EAR, Scart, TV-out, audio out, printer, ZX Bus

Frissítve: 2012. január 07.

ZX-One Germany United States Italy
C-One revision 2

Commodore 64 and ZX Spectrum clones in the same machine? Yes, this was regarded as a fairy tale for a long time, but nowadays became truth. Even not only the two machines above, but also VIC-20, CPC, turbo-CPC, Amiga can be found in the C-One mainboard.

The C-One (or C1) is the development of the American Jeri Ellsworth and the German Jens Schoenfeld (Individual Computers) from 2002

This is an FGPA-based C-64 clone, which is similarly to the Sprinter, capable of simulating more machines. For emulating these platforms, so called 'cores' must be loaded into the FGPA, from which two fitted onto the mainboard.

The so-called FGPA extender card contains a new Altera Cyclone 3 FGPA , which is necessary for emulating the new machines (Amiga, Spectrum).

The specification of the mainboard are quite standart nowadays. PS/2 mouse and keyboard, SVGA monitor, IDE and PCI ports, only the audio output is not placed at its standard place. The processor is 65c816 with approximately 20MHz speed. This one is 6502 compatible with 24 but memory addressing. Above this, any 8 bit CPUs can fitted onto the mainboard. Mains specs: 1GB SDRAM maximum, from which maximum 128MB for multimedia of course with DMA access.

The system loads the cores from so-called boot-ROM from either CF-card or winchester. So PC data change is possible and easy. Above the IDE DMA port, there is a floppy interface too, and serial and parallel socket also.

The PAL 48K ZX Spectrum core (v1.0) was made by Alessandro Dorigatti on 2011 May 24. It also supports the ULA+ 64 colours mode beside the standart Speccy gfx mode. At present, .TAP files are supported, .TZXs are not.

The Z80 processor is emulated by the T80 software core. The ULA emulation is based on Chris Smith's ULA book (see later). Although among Dorigatti's work this emulating the less precisely the original Spectrum, all test programs ran without any errors (of course, excepted the routines, which are indentifiyng the CPU). As the C-One mainboard does not contains SD-card socket, only two IDE-ports, the author does not planning its further development.
Technical specifications
CPU: 65c816@20MHz
RAM: 16M-1GB
ROM: 512K
Video: 256x192, 15 colours; ULA+ 64 colours
Sound: beeper emulated (8 ch. stereo DMA)
Keyboard: PS/2
Joystick: Kempston
FDD: ?? (reserved)
others: VGA, audio in/out, Centronics, RS232, IDE DMA, PCI

Frissítve: 2012. június 08.

Turbo Chameleon 64 Germany Italy
Turbo Chameleon 64

This multi purpose C64 expansion card is the product of the already known Jens Schoenfeld (Individual Computers) and the similarly German Peter Wendrich (Syntiac.com).

The development began in early 2006, the project was originally titled VGA-64. It was constructed to double the picture of C64 and lead it out to VGA monitor.

As the FGPA left too much opportunity opened, it was further developed to a multi purpose C64 expansion unit. Even it works as a complete configuration without the C64.

Developers now are concentrating more to this device rather than to the C-One board.

Again let's skip the C64 specific parts, let see what contains the v2.0 core by Alessandro Dorigatti.

The core can be downloaded from the website, and can be 'flashed' with the USB cable, just like with the another configurations.

This emulates at 'medium level' the original Spectrums, fits between the C-One and V60Z80P. This already emulates both 48K (PAL/NTSC) and 128K (PAL) Spectrums, along with AY-support. Also ULA+ 64 colour compatible.

The mass storage is the FGPA adaptation of the Italian ZXMMC+ interface. The main operating system is Garry Lanchaster's ResiDOS with TaskMan and TapeIO preinstalled.

The Kempston joystick is emulated on the PS/2 keyboard's numeric pad, or on the CDTV remote control unit.
Technikai specifikációk
CPU: ??
RAM: ??
ROM: ??
Video: 256x192, 15 colours; ULA+ 64 colours
Sound: AY+beeper emulated
Keyboard: PS/2
Joystick: Kempston (emulated)
FDD: ?? (reserved)
others: VGA

Frissítve: 2012. június 23.

V6Z80P Great Britain Italy

The V6Z80P is a complete new FGPA-based 8 bit computer architecture from Phil Ruston.

Its hearth is the Xilinx Spartan 2XC2S180 FGPA and a Z80 at 20MHz. The memory size is 512K, which is used both by the Xilinx and Z80. It has further 512+128K RAM, which used by the FGPA solely.

In Phil's config the OSCA config (Old Skool Computer Architetkture) runs the FLOS (Freezer Like Operating System).

A Pendulum daughterboard was also made for the system, directly designed for enhancing the memory timings for ZX Spectrum emulation. It was done for the request of Alessandro Dorigatti who made the ZX Spectrum core.

The v2.3 core is emulating the ZX Spectrum 48K/128K and Pentagon 128K machines. The 48K emulation works in PAL and NTSC mode. The last two machines only in PAL. The Pentagon mode uses the special memory timings of the Russian machine.

It emulates two AY-chips in ABC-stereo mode, as well a mono Covox. Can be run at normal 3,5MHz or turbo 7MHz speed. The picture is led out through VGA or Scart output. It uses the Issue 2 keyboard for better compatibility. Supports the ULA+ 64 color mode, the Timex Multicolor, the Timex Hi-res screen modes, except in Pentagon mode to achieve better compatibility.

The virtual DivMMC interface is also part of the system. (DivIDE with 8K EPROM and 256K RAM and ZXMMC+ interface with SD card support). Its main operating system is Miguel Guerreiro's esxDOS. The Kempston joystick can be used in port 1, as well there is a possibility to load the programs from external source with a 3,5mm jack, if you want it instead of SD card.

Updated: 2015. July.

Pendulum v1.1
Pendulum v1.1b

ZX Spectrum on pipistrello Hungary Spain

The aim of this project to create such ZX Spectrum clone, which has HDMI output. Laszla Jozsef (aka Joco) choose the Pipistrello FPGA card, which is based on the Spartan-6 LX45 FGPA, here is the ZX Spectrum on pipistrello name from. It is because it has HDMI output, the FGPA is enough large, and the 64 megabytes of DDR RAM is enough for everything.

For the creation he was used Miguel Angel Rodriguez Jodar's FGPA ULA implementation, as well Mike Field's (hamster) VGA-DVID project.

He was choose the 720x576 resolution with 50Hz refresh rate, the closest to the Spectrum. Speccy is using 7MHz for timing, HDMI 27MHz. Joco was set the machine to 28MHz (4x7) to achieve timing compatibility. Quite interesting, works fine with the TV, although uses only 524 lines instead of 625.

Steps are the following: porting Miguel's code onto the LX45, as well to upscale the picture. Then to connect it with the HDMI interface.

The PS/2 interface and the EAR is also realized inside the FGPA, last one is based on the Issue 6. The sound of Spectrum can be heard through the audio output of the card.

The result is fine, 99,5% faithful emulation in this card made in 2013.

Added: 2015. July.

ZX Spectrum on pipistrello

Multiple Classic Computer United States Italy

The MCC, also known as Multiple Classic Computer is a console, which can emulate some old machines. Can be mimic Commodore 64, Amiga 500, Atari 2600, Atari 800XL, Apple Iie, and which is the most important for us, also the ZX Spectrum. It is the product of Arcade Retro Gaming located in the United States.

It has two subversions: MCC-216 and MCC-TV Their common features, that the CPU, sound generator and interfaces are freely configurable in the Altera Cyclone 3 FPGA, and they have 16 megabytes of SDRAM. All of them have stereo output, and programs can be stored on MicroSD card.

The MCC-216 has 2 megabytes of Flash memory, in which of course could fit the programs alongside the confogrations. Also has PS/2 mouse and keyboard connectros. The picture output can be either S-Video or VGA.

MCC-TV has composite TV out. Unfortunately, its Flash memory only 128K(?). But has two USB joypad connectors. (USB v1.1).

The ZX Spectrum core by Alessandro Dorigatti is usable on both machines, but sadly, only the v1.0. So we get a 48K Spectrum in PAL or NTSC mode. The Issue 2 keyboard is emulated for better compatibility. Floating Bus and Snow effect are also emulated successfully. Also available the ULA+ 64 color mode and the ZXMMC+ interface with 512K+SD card interface combination.

The Kempston joystick emulation works on both Atari and USB ports. It arrives with Garry Lancaster's ResiDOS-a with TaskMan and TapeIO preinstalled. We can load the .TAP files from the Launcher menu made by Arcade Retro Gaming itself.

Hozzáadva: 2015. July.

MCC-216 (S-Video)
MCC-216 (VGA)
MCC joystick

ZX-Uno Spain

The ZX-Uno FGPA-based clone (mo' exactly the card) is done by five Spanish guys, well-konwn in the Speccy scene. McLeod_ideafix, Miguel Angel Rodriguez Jodar is the PR-manager, SuperFo SuperFo is the PCB dezigner, AVillena (Antonio Villena) is the father of idea, circuit and prototype dezigner, Hank0 (Jordi Bayopedig) is the gfxman and web dezigner. Quest - Samuel Baselga is a new member, also involved into PCB and schemtics design.

The clone exists only at hardware level at the moment, programing of FGPA is undergoing process. The 512K SRAM is limiting the number of machines: maximum size of RAM(s) and ROM(s) can be 512K.

The machine fits into the RaspberryPi case, most outputs are designed for it. The RCA video, stereo 3.5mm jack, SD card and power micro-USB in its original place. Atari joystick placed into the USB hole, the JTAG/RGB is in the HDMI, PS/2 keyboard slot mounted into the Ethernet socket. But it is necessary to drill the place of tape port. Unfortunately, for cost effective reasons (at least at the moment) nor the Sinclair edge connector, and nor the USB keyboard is not implemented.

From the .TZX, .TAP, .DSK and .TRD files, only the .TAP will be surely supported on the SD-card. Others are big question mark. Maybe the HxC will be implemented into the FGPA core.

Beside the Spectrum, the Russian clones, the SAM Coupe and more simple machines (ZX80, ZX81, Jupiter Ace, Z80 PacMan etc.) also can be realized.

Made in two subversions. First one is a 22 Euro developer edition, on which the parts not mounted onto the PCB. 10 pieces were already made. The end user edition will be around 30-40 Euros, and it is fully assembled and programmed. 50-100 pieces is the sale plan from it.

Updated: 2015. November.


Dual-CPU/MCU development board Czech Republic

The main idea of constructing of Dual-CPU/MCU development board was drafted by the pandora.cz newsgroup. To summarise: create a new platform, which is ZX Spectrum compatible. The board is married the good old Z80 and Z8Encore! processors, it was realized by Ik0n, aka Imrich Konkol.

Hearth of board is the Z8Encore!, controlling all another peripherals, even the Z80, beside the serial port, LCD screen as well the memory.

The prototype worked fine, but the developer is trying to make further innovations of the original ZX Spectrum design. MMC card interface, 512K RAM support, keyboard-port (original ZX Spectrum layout and PS/2 standard) will hopefully integrated. In addition, the Z80 will also support the peripherals, which are only used by the big brother momently (UART, IrDA, I2C).

The actual Nokia mobilphone screen will also be replaced with an original ZX Spectrum resolution one by the plans of the designer.

Sadly, last update was in 2004.

Updated: 2018. October.

Dual-CPU/MCU development board

aSPECT development board


The aSPECT development board is a development device for enthusiast Spectrumists from aniSKY. The card saw the light in 2010 in the Belarusian Minsk city.

Consists of four circuits: the ALTERA EP1C6T144 (or alternatively the EP1C6T144) FGPA, the configuration ROM, 128K SRAM, as well 256K Flash EEPROM.

Supports the basic Speccy functions as keyboard, kempston joystick and video controller.

Another I/O functions of FGPA is reserved for controlling and testing the modern devices (SD card, IDE, USB ports etc.).

Added: 2010. February 26.

Aspect 128 AVR ZX Spectrum Russia

The Aspect 128 AVR ZX Spectrum board is the work of Vasil Lisitsin radio-amateur from 2012. This development is compatible with 48K/128K/+2/+3 machines as well with Pentagon. Further more, it is virtually capable of emulating all clones up to 512K.

All documented and undocumented Z80 commands are emulated within the ATMega-16AU circuit. Here are the I/O commands also. The PS/2 keyboard is controlled by the ATTiny 2313A-SU. The card is also handling the shadow screen.

The whole project is detailed and documented on one of the most significant radio amateur website.

Added: 2013. March

Aspect 128 AVR ZX Spectrum

Just Speccy 128k Spain

The Just Speccy 128k mainboard is the clone of Zaxon (Piotr Bugaj). This one is 128K compatible one, which fits into the 16/48K(+) cases.

The storage is PicoDivSD, which is the own DivMMC clone of the author (an advanced DivIDE development) and runs the esxDOS operating system. Also got the Kempston joy interface. The RGB picture comes from a 8 pin mini-Din socket. It contains the usual AY-stereo mod.

Added: 2016. January

Just Speccy 128k

TBBlue Brazil

The joint project of Fabio Belavenuto (FB Labs) and Victor Trucco (VTrucco)is the TBBlue clone. After the successful re-engineering the ULA, was raised the idea of this FGPA-based development. This contains several clones and peripherals. Beside the 48K and 128K Spectrums, the Brazilian TK90X, TK95; ZX Spectrum 128K+3e, ZX80, ZX81 and Jupiter Ace can be configured.

DivMMC DivMMC became the mass storage with esxDOS support. This can handle maximum 8 Gigabytes of FAT32 partitions. From this loading the firmware ROMs and programs in .TAP format.

Sound is AY-3-8910 and YM2149 emulation through stereo jack, MIC and EAR got separate connectors also.

Two joystick ports are also fitted, can be configured as Kempston, Sinclair and Cursor 2. To the second port with a PS/2 adapter can be connected a mouse or lightpen.

The favourite device of crackers, Multiface was also integrated which operates as One, 128 and +3 mode, depending on the choosen clone.

Standart PS/2 keyboard/mouse (Kempston compatible) and VGA connector also can be found. Supports the ULAPLus mode too.

Finally was realized in two flavours. Fabio was designed it to fit into a box. Opposite of it, Victor’s board can be placed inside the case of the original 48K Spectrum or TK90X/TK95.

For all of two must be bought separately the FGPA card (EP2C5T144 Mini). First is from 2015, last one was born in 2016.

Added: 2016. April

TBBlue by Fabio Belavenuto
TBBlue by Victor Trucco

ZX Spectrum Next Brazil Great Britain

ZX Spectrum Next is an extended FGPA-based clone, that, in addition to being fully compatible with the original, includes the most significant enhancements of recent years. Actually, it is the further development of Victor Trucco's TBBlue clone. Was started as a Kickstarter project, originally needed 250,000 pounds. Since it was overwhelmed in very short time, was also expanded the original planned specifications.

The original SLX9 FPGA was replaced by the SLX19, leaving 60% more space for the expanding of original ideas. The processor is of course Z80. It was planned to run at 3.5 and 7MHz, but was expanded with the 14 and 28MHz modes. The ESP8266 Wi-Fi module is an optional device. Both the extra memory and the wireless network card were supposed to be soldered on the motherboard. Thanks to the amount was received, they got a standard slot on the motherboard.

Memory map looks like the following: ZX Spectrum ROM (64K), esxDOS ROM (16K), Multiface ROM + extra ROM (16K + 16K), divMMC RAM (256K), ZX Spectrum RAM (128K), extra RAM (512K).

Also optional the real-time clock This can be connected through a dedicated port to the system board, not using the original edge connectorm which is compatible with the original. It is also a mini-circuit built around the DS1307 chip. This clock is currently being solely used by esxDOS, but the new special games will also be using it.

In addition to the original resolutions, it also offers a new mode. It supports 256 colors and hardware sprites, any pixel can be any color. This means 64 objects in 16x16 size. Video memory is stored in FGPA's own RAM. Sprites can also be placed to the Border area. As video output, you can choose between RGB, VGA and HDMI. The SD card adapter uses the divMMC protocol.

Audio part emulates 3 AY chips, and the MOS IC 6581 (SID) is also simulated from the Commodore 64 So Turbo Sound emulation is solved too, system is ABC or ACB stereo. Besides 9 AY channels and 3 beepers, we can play C64 tracks as well.

The conventional BD9 joystick connector supports Cursor, Kempston and Interface 2 modes. Originally only one piece would have been mounted on the motherboard, but thanks to the extra support, its number was doubled. You can use a Kempston compatible mouse or external keyboard via the PS/2 port. F-keys received special functions. If not connected, the same functions can be called by pressing the M1 key and the current key code (F2=M1+2).

It is also possible to use a cassette unit with the MIC/EAR connectors.

An optional accelerator card got a separate slot. This is Raspberry Pi Zero, which memory, CPU and GPU can also be used by developers. The best news is, that it can be incorporated into the original machine case.

Who are standing behind the project? Rick Dickinson, who was designed the case, which unifying both classical and modern design, and was responsible for ZX80, ZX81, ZX Spectrum and Spectrum + and QL designs.

Fabio Belavenuto is the father of the TBBLue motherboard, which was the starting point for the Next. On the side of hardware development, we also must have to mention the Brazilian Victor Trucco.

Jim Bagley is a well respected programmer of the classical era. For example, he was involved into the creation of new video modes and hardware sprites. He also coordinates the developments of the platform.

Henrique Olifiers was also invited, he was originally involved in the development of the TK-90X clone.

In addition to the hardware developments, a strong international volunteer game development team was also rectruited.

The motherboard is made in the same place where ZX Spectrum Vega, in the SMS Electronics factory.

Let's see the boot process! When powered on, the 48K machine loads along with divMMC. But not with the original ROM, with a special loader (Initial Program Loader - IPL). This 8K long code is loaded into the RAM from FlashROM. This initializes the ULA and the SD card. After this, booting from the SD card continues with the following choices: boot, editor (pressing the space button) and updater (U key).

The Boot section loads an .ini file, this information including for example the current machine type (eg. 48K or 128K), the active or inactive status of divMMC and Multiface. Accordingly, ROMs are loaded into the RAM, and this part of memory become read protected.

In Editor mode, you can change the content of the .ini file mentioned above by a menu. First, must select the type of machine, then turn on-off the devices and configure them.

When using the Updater module, version of the current hardware firmware is read out, and the system will wait for confirmation. After approval, FPGA flash will starts.

The "Anti-brick system" makes it easy to restore the old version if the new one does not work (M1 and drive buttons).

Added: 2016. May

ZX Spectrum Next CAD file
ZX Spectrum Next rendered file
ZX Spectrum Next prototype Issue 0
ZX Spectrum Next prototype Issue 1

ZX Spectrum Vega, Vega+ Great Britain

ZX Spectrum Vega is a modern rethinking of the ZX Spectrum as a console. Sir Clive Sinclair is the father of the idea. Can be mentioned the name of Dr. David Levy, who is a chess grandmaster and also involved himself into the research of artificial intelligence and computer games. Chris Smith also participated in the development, who was designed the original Spectrum.

Design and production was done entirely in Britain. Was designed by the Retro Computers company located in Luton connected to Clive Sinclair. Production was took place at SMS Electronics Ltd of Beeston in Nottinghamshire.

As back then Amstrad bought the Sinclair company, the project was done within the license agreement of its successor, the Sky In-Home Service Ltd. By crowdfunding was launched the project using the Indiegogo page. A total of £150,000 has been collected, which exceeded 50% the original plans. This amount was enough for making the 1000 first series to manufacture and prepare the next bunch.

The 48/128K-compatible equipment was launched to the market for £ 100, has not a full keyboard, however, its box is completely recalls the ancestor. For the built-in games was aligned this few buttons and on the screen you can use virtual keyboard too. Planned to have the option of fitting an external keyboard also.

Enough for it a single TV-set. Power is given by the TV's USB port, in addition, only necessary to connect the audio and video. Contains 1,000 pieces of burnt-in games, but with an SD card to your hand, much more we can achieve (.SNA and .TAP files). The machine contains partly classic games, partly the born of new age.

ZX Spectrum Vega+ also thanks its birth to Indiegogo. This handheld console is very much like the PlayStation Vita. By the original plans they wanted to collect 100,000 pounds, which came together in the first two days. In total, more than half a million was collected, showing the popularity of the platform – also winning the most popular campaign title. The sum was planned to manufacture the first 2,500-piece series and to prepare the second one. For now, introducing to the market is fairly delayed. Design, manufacturing and license thingies are the same as for those previously mentioned.

After the campaign is finished, the machine still can be ordered for £100, but only in black color - red, white and blue limited colors are not available. Design was made by the original designer of Sinclair machines, Rick Dickinson.

The classic 4: 3 LCD screen is ULAPLus compatible, controlling is done by D-pad style buttons, which is Kempston or Cursor joystick compatible. Among its connectors, the jack is multi-functional: serves as stereo audio and composite audio/video output functions, the latter one for PAL/NTSC devices. The MicroSD slot can accept SDSC or SDHC cards, the game position saving jobs and storing POKE files as well firmware updates can be solved with it, also support .SZX snapshoot files.

With the Micro-USB charger 6 hours of playing time can be obtained. It also contains 1,000 pieces of burnt-in games. Has sound and bright controls, and has been resolved the connecting of an external keyboard too.

In both cases, the first "customers" who supported with any plus amount the start-up campaigns, can obtain extras aside the hardware. In addition, to the limited edition machines can be included on the list of supporters for Vega, artworks with Sir Clive’s signing, receive a book from the creation Vega or share a dinner with the team.

For the case of Vega+ with Rick Dickinson’s signature or visiting the SMS factory may be wealthier the donors.

Added: 2017. March

ZX Spectrum Vega
ZX Spectrum Vega+

ZX Prism Australia

Beginning of creation of ZX Prism clone is leading back in the 1980s. Then Jeff Braine (aka SJB) drew up a “wish list” of features he would like to see in whatever Spectrum came out after the ZX Spectrum 128K. Over the years, this list was modified and expanded, and eventually became the specification of ZX Prism - a Spectrum-compatible clone with more memory, screen modes, colours, some form of mass storage, built-in mouse and joystick interfaces as well Multiface.

ZX Prism was planned to be “as compatible as possible” with software for the ZX Spectrum 48K, Spectrum 128K, Spectrum 128K+2A/+2B/+3, Timex, ZX Spectrum SE, and other clones like Pentagon, Scorpion etc. It was also important to Jeff, that he wanted to use “real” cassettes. Emulating of some classic, Russian and current peripherals were also aimed.

In mid-2011, first “proof of concept” tests were commenced, using a Terasic DE1 development kit, the heart of which is the Altera Cyclone II 2C20 FPGA. A number of open source FPGA based computers were looked at to get ideas of how they were done, including ZXGate and both of Mike Stirling's FPGA Spectrum projects. Starting with Stirling's 128K ZX Spectrum on FPGA core as a testbed (for example, the idea of supporting ZXMMC+ also came from here), and its video module was heavily modified. It was because to prove that realization of higher resolution screen modes, user definable palette and different ways of decoding the screen data were possible. In the end, Prism's video module became a complete replacement, with no original code left (but of course, the original code provided a great amount of insight into the methods, how the video signals were generated).

Additional plans were a PS/2 compatible keyboard connector, as well an RGB/VGA output. The whole emulation was designed to be lay on T80 opencore.

Memory content would have been stored in DE’s SDRAM and the ROMs in the FlashROM. Maximum RAM would be 1024K (for emulating the Pentagon 1024) along with 64K videoRAM. Memory contents could be saved by Magic Button. Real or emulated beeper, AY (ACB/ABC stereo) and SID would be responsible for sound generation. In addition to the +3 disk emulation, DivIDE was the designed as mass storage. CPU would have ticked at 3.5, 7, 14 or 28 MHz, while controlling would done by Kempston, Sinclair, AGP joystick and Kempston mouse.

Screen resolution is planned to be selectable between 256x192, 256x384, 512x192 and 512x384 with 8x8 and 8x1 attribute grids in case of regular ULA and the ULAplus modes. The 256-color 16-bit attribute mode would have been available for 8x8 squares also and its "chunky" version only 1 bit. Above the standard resolution, would have a 16-color planar mode, as well as hardware-accelerated, so flicker-free Multicolor and Gigascreen modes. ZX81 compatible text mode was also planned thanks to ZXGate. Some another text modes were also planned.

The 32 colours (actually 29) mode was created by rewriting Mike's code. Turning off the 7th bit of Flash attribute leaded to a 2-bit Bright attribute. This make possible 7 different colours with 4 Bright attributes and 4 same shades of black, totally resulting 29 different colours. Attribute size was remained 8x8. Further more, this mode was expanded by extending the code to availability of selecting 256 colors for the Border. This was achieved with an 8-bit ULAPlus style palette (2 bits blue, 3 bits green, 3 bits red - BbGggRrr). Later, this three gfx modes can be selected either from Basic and machine code, the 256 color Border mode is available in each. A true 256 colour mode have been also created, only restriction, that Paper and Border must have the same colour, Ink can be used freely (called mode 72).

From here, the first true ZX Prism prototype was built. This was a hybrid machine with real chips, but with a mini developer card containing a Cyclone II FPGA, which was replacing the ULA - majority of the ULA model would be taken from the video driver of the “proof of concept”. So was designed with a real Z80 proc, 29C040 512K Flash ROM, 1 megabyte of RAM (3x628512 RAM modules) and 64K videoRAM (2x61256 modules) they were added on a veroboard to support the FPGA card. The processor already has variable speeds, works at 3.5, 7, 14 and 28 MHz, but only the first two were stable.

A real AY chip and SID chip would provide audio, and the floppy controller from a +3 would be added to add mass storage support along with DivIDE with the possibility of saving the content of RAM with Multiface’s magic button. Controlling would have been realized by Kempston/AGP and Sinclair joysticks and a Kempston mouse combo. All the stuff was built into a box with double SD card slots, reset, power and NMI buttons. Additional buttons were functioning as FLASH and NVRAM selectors, FLASH ROM write protect, ABC and ACB stereo mode selector. Joy, mouse and keyboard controllers and connectors were implemented on the separate card. The Allram mode of ZX Spectrum 128K+2A/+2B and +3 was also integrated. Emulation of ROM is available both from FlashROM and a 32 slices separately managed RAM, allowing emulation of 64K banks. It can also simulate the 1 megabyte Pentagon RAM in 16K slices. Video memory works in 8x8K segments, dynamically using the part what is actually needed.

Strength of this version was supporting different screen modes, whether it has 8x8 or 8x1 attribute grid. Of course it supports the standard ZX Spectrum mode and Timex 8x1 hi-color. By vertical and horizontal halving and quartering the screen, 512x192, 256x384 and 512x384 resolutions were realized both with 8x8 and 8x1 grids. In addition, was planned the hardware-supported 8x8 Gigascreen with 256x192 and 512x192 resolutions and also its 256x192 variant with 8x1 attribute. The 16+16 color mode is similar to the original, but here you can choose from 16 different Paper and Ink combinations. In the 42 colors mode, you can choose from 4 Bright versions of 8 colors. For the first 256 color mode, Ink may be any of color, Paper must match the Border. For the second, thanks to the 2 attributes, Ink and Paper can be freely chosen. In the 16-color Planar mode, four 256x192 screens will give the final color (blue, red, green and bright). The 256-color chunky mode uses 48K VRAM, assigning 1 byte for each pixel.

There were three palettes. Default has 32 colors, with the original ZX Spectrum 16 colors, and their darker versions. Used colors can be chosen from a hard-coded 256 colour palette (colours 0-15 being equivalent to normal spectrum colours, the rest being a selection of colour scales). Prism's own palette an user-defined 256 colour palette from a selection of 4096 colours (in fact Prism's specification allows for 24 bit colour, but the prototype hardware only supports this 12 bit colour depth at this point). GggRrrBb (aka G3R3D2 encoding) is the hardware equivalent palette used by ULAplus and MSX. After many hours of designing, soldering, coding and debugging, it became clear that this arrangement wasn't easily able to provide the full feature set of the ZX Prism.

After near two years, the second (and current) prototype is laying on a “Black Gold” FPGA development board which has an Altera Cyclone IV EP4CE15 FPGA. It was chosen, because it has enough memory for the planned new video modes. This version of Prism returns to being a mainly FPGA based solution – the ULA, MMU, video RAM, CPU, video and audio generation are all modelled within the FPGA. Also have 1MB Flash RAM on-board providing 256x16K user definable “ROMs”, so ZX Prism and ZX Spectrum ROMs got stored here. Only the main memory (SRAM), ROM (NAND Flash), audio low-pass filter and tape I/O functions were realized off-chip.

These are mounted on the author's specific veroboard, to which is linked a twin MMC slots daughterboard. The PS/2 and VGA ports on the vero overwhelm those on the developer card. Former was a faulty on the board, while the latter could only display 8 colors. The content of 32K videoram with 2x16K banks leaded to the external VGA port. Works at 50Khz (to match Spectrum) and 60Khz (to sync with video) interrupts. Notably ports for more advanced users are RS-232 as well a 7-segment LCD on the FGPA-card.

The clone utilizes 512K SRAM, which can be paged in at 0xC000. 128K of this also available for DivMMC, another 128K can be paged in using the Timex/Spectrum SE by sideways RAM paging ports. The special Allram memory modes of the 128K+2A/+2B/+3 are also supported. It is perfectly emulating the ZXMMC interface, but the author went further and full features of DivMMC became the target, which was realized successfully during the development. In addition, it works fine together with the emulated Multiface 128 too. Unreliability of the real cassette unit was also improved by replacing a resistor with a higher capacity.

Some another video modes was begin to realized. With connecting two DAC video lines, can be used 4096 colors instead of 256. This “Brainebow” mode is still experimental. 8x8 ULAplus mode was started to realization. Also was continuously improved the 256x192 16 colour planar mode. This uses 4 bitplanes to provide a colour-clash-free resolution display. Was inspired by the way the Amiga's display was stored. Also was begin to integrate a flicker-free Gigascreen mode, called Gigablend. It blends the main and shadow screens together in hardware to achieve the same colour blending effect as the software Gigascreen seen in many demos but without the flicker.

ZX Prism Version 0.1 was released on August 12, 2014. The Spectrum ROM was embedded into the FGPA's memory. With new resolutions (512x192, 256x384, 512x384) and new colors came out (16+16, 32 color, 256 color 1, 4 plane planar), ULAPlus realization was rudimentary. In the 16+16 attribute mode the Bright bit of the attribute controls the bright for Ink only, while the Flash bit controls the Bright for Paper. This allowing more colour combinations – for example bright yellow on dull yellow. Using the 32 colour attribute mode, the Flash attribute byte becomes a second Bright bit, so every colour has 4 Bright variants. When choosing the 256 colour attribute mode, Paper colour is the same as Border colour; Ink colour can be selected by the entire attribute byte range.

The shadow screen has not been implemented in the videoRAM yet. The CPU was stable at 3.5/7MHz. The PS/2 keyboard already interprets the Spectrum keyboard codes and also emulates the Kempston joystick. The veroboard’s VGA card can display 16-16 shades of red, green and blue. Tape in-out connector is also works, also functioning as beeper output. The currently used RAM and ROM segments are indicated by the LCD. There is, of course a reset button as well.

0.11 appeared just a week after. Already able to read the ULAplus palette. Emulation of keyboard has also been improved and the processor running stable at 28MHz. Special functions were assigned to the F-keys (for example F11 became reset).

After another week, the new version came out, v0.12. Contains CPU speed bugfixes and a number of optional frequencies were increased: Normal (3.5MHz) and Turbo (7MHz, 14MHz, 28Mhz) CPU speeds plus CPU speeds based on the pixel clock. 14MHz and 28MHz need to be “tuned” to make them more stable. In theory, 56MHz was its peak speed, but this resulted in accidental freezings. Also improved the addressing of expanded memory for both 128K/128K+2 and later models.

On September 10th, version 0.14 was became public. In addition to the new graphics modes, it was included bugfixes and started OSD implementation. Soon followed by 0.15, in which was finalized the ZX Prism palette. Instead of the 64 Ink and 4 Paper mode which was already implemented, the 3 plane planar mode was finalized according to Andrew Owen's specifications. This 8 colour planar mode uses 3 bitplanes to provide a colour-clash-free 256x192 resolution display.

Development of the next month is 0.16. From now full capacity of FlashROM can be used and memory can be limited to 128K. Was began the implementation of MMC part and the usual bug fixes and enhancements were done. The New Year brought many novelties. As FlashROM can store the Speccy ROMs, we can use the total 256 pieces of 16K slices. Also possible to use emulated ROM if the FlashROM might not work for some reasons. This SAFE ROM option is available with the combination of reset (F12) and F9. The ROM can be changed and written on the machine (Programming ROM mode). For testing purposes, ROMs of 16/48/128K/SE and ZX Spectrum 128K+3e ZXMMC images were burnt in. Of course, realizing of DivMMC emulation has continued with partial success. Save, load, and rename processes were succeeded, as did the autoboot feature. Also boots from Interface 2 ROMs. The memory paging scheme of Chloe 280SE was appeared too, just like the Timex/Chloe screen modes. The shadow screen of those are perfectly emulated in Prism, and also the Timex Hi-Color mode is done.

The 512x192 mode of Timex/SE/Chloe is monochrome, but all colors are available in Prism’s case. Of course, using of the monochrome version is not problem. Prism's high-colour is 256x384 with 8x1 pixels. The AY chip is also been emulated in the FGPA. Kempston joystick also works, and the VGA DAC was similarly improved. During Easter was done the Timex/Spectrum SE/Chloe 280SE and the Spectrum 128K/Pentagon memory paging system. Prism from now automatically booting from SD card and a T80 bugfix has been realized too.

By the end of summer, was finalized the use of 128K+2A/+2B and +3 Allram mode. Not many programs are using it, perhaps only CP/M and John Elliott’s ZxZvm program, which emulates a "Z-machine". With this, you can run the adventure games of Inform company based on the Z-code. Another novelty is using of the dynamic video memory mode.

A new graphical mode was also implemented, inspired by the low-res multicolor mode of C64. This reduces the 8x8 cell to 4x8, but the number of possible colors was doubled from the original two. He was tried two different versions. One with the original resolution, the another is similar to the Commodore, with halving the number of horizontal pixels. Thus were born the "Antialias" or "progressive" 256x192 4 color-per-cell and Chunk-o-vision 128x192, 128x384 and 256x384 4 color-per-cell modes. It has one Paper and three Ink attributes.

The new year, 2016, was the time of minor changes. For example, increased the stability on a higher clock speeds, and with tampering the microcode was improved the later expansion possibilities. Radastan's 16-color color-clash-free 128x96 mode was also realized with its double-sized pixels. This 4-bit screen uses 6144 bytes, the palette consists of the 64 colours of ULAplus. From here, only one step was using of Cesar Hernández Bano's 256x96 (mode 5), 128x192 (mode 7) and 256x192 (mode 9) screens with similar features (called ZEsarUX modes, named after the author's emulator). After a half a year, ESXDOS works well with both ZX Spectrum 128K+3e’s ZXMMC and DivMMC, thanks to the SPI port routines. Thus, with partial TR-DOS emulation was possible with those programs, that do not use the lower 16K segment and more than 128K RAM.

Finally was realized Gigascreen's flicker-free, hardware implemented mode, and got the Gigablend name. Brainebow mode has 4096 colors. Any pixel can be black, blue, red, magenta, green, cyan, yellow or white/gray along with 256x192 resolution. The 8x8 grid can be attributed as red, green, and blue. The 128x128 resultion, linear colour-clash-free 256-color mode uses 16K VRAM, and the 256x128 variant its doubled amount.

After about a year's break, the audio section was completed. So far only the beeper and tape outputs have been realized. These are from now also serving as audio outputs. Two pieces of YM2149 became emulated, which are simulating the 128K Speccy’s AY-chip and also Turbo Sound. Covox, SounDrive, SAA1099 and Spectdrum was also been implemented. The two channels received two separate DAC circuits with own multiplexers.

ZX Prism on Cyclone II
ZX Prism on Cyclone IV

ReVerSE-U16 Russia

ReVerSE-U16 is a Cyclone IV EP4CE22E22C8N (7N) FGPA chip based developer card, designed primarily for emulation of 16-bit systems. At present, it emulates a wide “spectrum” of 8-bit micros, including Speccy clones. Unlike other hobby projects, it supports USB, HDMI and Ethernet interfaces. Otherwise, it is also compatible with some another Cyclone FGPA products such as the III EP3C5/10/16/25 and IV EP4CE6/10/15/22.

It has 16 mega SDRAM by default, but also can be configured with 4, 16 or 32 megabytes. Its flash memory is 64 megabytes, but it can also be downgraded to 1 or 16 megabytes according to your needs. For storing date and time a DS1338Z chip is responsible with a 2032 button cell. The HDMI output of course, also acts as an audio and video output at the same time, and has two USB 2.0 ports and a microSD connector. Take a look at the emulated ZX hardware.

Let's start with NextZX. It is a pure Spectrum, but its processor is an emulated NextZ80 at 48MHz. In addition of supporting all Z80 features, has the speed of approximately a 200Mhz real Z80. There is also a possibility of using a T80@50MHz based ZX48T80 configuration. In both cases, the beeper sounds in stereo.

Quad Speccy is the four Spectrum mode. Its processor is based on the T80 softcore Z80 emulation, supported with 4 megabytes of RAM. In basic configuration, the Z-Controller with an SD card is the mass storage. For the similarly supported DivMMC, ESXDOS is a supported operating system. The emulated sound system can be TurboSound or Soundrive. Real-time clock is simulating the MC146818A model.

With Spec 25 emulation, you can play classic ZX Spectrum games in 256 colors. This initiative is a fairly old Spanish creation, which is actually an emulated (so in reality non-existent) Spectrum. The graphics chip is a virtual unit, called Z80_GFX. Aside to the extended colors, other specifications correspond to the traditional ZX Spectrum: 16K ROM and 48K RAM. Keyboard is USB emulated, screen is scaled to 640x480 by HDMI, and the beeper is also sent via this to the TV stereo. The processor initially had 8 T80s at 3.5 or 7 MHz, later replaced by the "original" GFX_Z80. It also supports the Game Master G2 controller. Games are available from a pre-flashed menu.

In case of 128K Spectrums the T80 virtual processor runs at 3.5MHz. ROMs are stored in RAM, while the 640K SDRAM shared into 128K memory and emulating the 512K DivMMC. The sound is AY3-8910 in stereo and the beeper.

TSCONF is the already known Pentevo firmware tuning. It supports Kempston Mouse Turbo and Turbo Sound (with 2 pieces of YM2149 emulation) and also the SAA1099 music chip.

ZX-Poly is the development of Igor A. Maznitsa between 1994 and 2011. Its idea was based on the fact, that almost all of features of the ex-Soviet ZX Spectrum clones have been improved - exception of screen features. The machine is built with 4 Z80 processors and contains 512K RAM. The first video mode is compatible with the ZX Spectrum. However, due to the 4 processors, not only two screens can be used as shadow screens for 128K Spectrum, but eight at once. The real novelty is when the four CPUs are simultaneously involved in picture processing. For Video Mode 4, the first processor is handling the Red component, the second for the Green, the third is the Blue, and the fourth is responsible for the brightness (Bright) attribute. This makes possible the color-per-pixel mode using four layers. Video mode No. 5 has 512x384 resolution. Here, each processor produces a two-color image (R, G, B, and Bright), that will result the final image.

ReVerSE-U16 Revision A
ReVerSE-U16 Revision C

ZX Max, ZX 128 Spider, ZX Nuvo Spain

ZX Max 48 is a ZX Spectrum 48K clone designed by Superfo. It is excellent for novice builders, since can be soldered with a simple soldering-iron. This “project” is completely free, and was built with a real Z80 CPU, which is controlled by a software-upgradable Altera Max7000 EPM7128S CPLD. The motherboard is designed to be able to build into the housings of ZX81/TS1000. The 2x16K ROM is fitted into the static RAM of CMOS.

Issue 1 motherboard was released in October 2017. First series was launched along with the CPLD version 1.0 and closed with v1.3 firmware in February of following year. There was also constructed an interface for adding a Kempston port, a ROM cartridge connector and reset button.

In December of 2017, Issue 2 was came out, which was already integrated the joystick controller and added AY-3-8912 support.

Both cards were born with an audio I/O bug, but they can be eliminated based on the published wiring diagrams (Mod.i1.1 and Mod.i2.1).

Issue 2 in addition to previous bugfixes, also received a composite RCA output in February. CPLD versions -useable for both versions- were begin with 2.0, and closed by firmware v2.3 on the last day of January.

CPLD codes are otherwise not interchangeable between Isssue 1 and 2 boards.

From Issue 2, it is possible to upgrade to 128K. For doing this, needed to replace both RAM modules with 628128 chips and the ROM with 150-200ns access time E(E)PROM. In addition of reprogramming the CPLD, have to make six patches on the motherboard. If in 48K mode occurs problems with audio input and video output, there are also exist patches for it.

ZX Max 128 contains these innovations already integrated. The CPLD versions of the 2018 February released Issue 1 board starting from 1.0 (April) to v1.3 (October).

This machine was buggy for first time: in some games and demos, images became ghosted. So needed to change the memory bank addressing. It was fixed by the Altera EPM7128SCT100 with PLCC84 socket, as it has higher capacity and has direct access to processor data lines. First version of CPLD, v1.2 was released in May, the last one, v1.4 in October.

Further more it is necessary to connect five direct data lines to the processor. Also possible to choose between 48K and 128K timings with this implementation.

Skoti, one of the a members of the Polish Speccy.pl community, upgraded both machines with the name ZX 48 Spider and ZX 128 Spider. They can be installed in the rubber and 48K+ housings.

Both come standard with Kempston joystick interface and RGB video output. In addition to AY-3-8912, the AY-3-8910 chip can also be installed. For the 48K machine, the Altera Max7000 EPM7128SLC84-15N, for 128K, the Max7000 EPM7128STC100-15 controlling the system.

At the big brother, the integrated DivMMC interface is simulated by the Xilinx XC9572XL, which in this case supports a single microSD slot.

The firmware has been further developed by the Polish Speccy.pl community from ZX Max. For 48K, it is based on the ZX Max 48 Issue 2. In the case of 128K, the focus when programmed the CPLD, the DivMMC was in the focus.

Superfo was also made the 48K(+) housing versions. ZX Nuvo 48 is an enhanced version of the ZX Max 48 Issue 2/2b, and their CPLD firmware can also be used for it.

It also includes a built-in DivMMC interface too, with a double SD card slot. The microswitch keyboard is integrated onto the motherboard, but also possible to attach the regular foil membrane. Issue 1 motherboard is dated to January 2018.

ZX Nuvo 128 is a ZX Spectrum 128K compatible clone based on 74HCxx discrete logic circuits. The mainboard can be fitted also into the 48K/48K+ cases, and beside of standard 128K compatibility, has all expansion of above clones. Motherboards were made between April 2017 (Issue 1) and March 2018 (Issue 2b).

The Kepmston Joytick Interface Unit, which was initially buggy, can be fixed using a ZX Nuvo Kempston Fixer mini-card.

Updated: 2019. January

ZX Max 48 Issue 1
Kempston If for ZX Max 48 Iss 1
ZX Max 48 Issue 2
ZX Max 48 Issue 2B
Max 48 Iss2B to Max 128 Is1 upgrade
ZX Max 128 Issue 1
ZX Spider 48 rev 1.1
ZX Spider 128 rev 1.1
ZX Nuvo 48 Issue 1
ZX Nuvo 128 Issue 1
ZX Nuvo 128 Issue 2B
ZX Nuvo Kempston Fixer

Sparrow 48K Czech Republic

Sparrow 48K (formerly known as Sparrow LITE) is a mainboard from Jiiirija aimed to replace the faulty ones in Spectrum and Spectrum + machines, wherein the ULA or the Z80 processor is still working.

For this purpose, it is compatible with all ULA chips and the connector pinouts are also designed to be mounted into the original housings. Compared to the original 48K machines, Sparrow offers some enhancements. For example, the video output is composite and not modulated TV-out. The VRAM and RAM are also in integrated into one and one SRAM chip. ROM is placed into a 128K Flash EPROM, so you can choose from 8 different types with DIP switches. It was also received a reset button port. The control logic is Altera EPM3032 or 3064 CPLD. Its Power system was also been improved, so producing far less waste heat.

The first prototype (marked with 0) was presented at the Bytefest 2012 party. It was based on two separate cards and unfortunately did not work on the show.

Prototype 1 appeared in 2014 and was worked well.

On prototype 2, the inverter circuit was integrated onto the motherboard.

The forthcoming prototype 3, was received a more cost effective inverter, and the final product, Revision 4 is based on that. The last prototype is easily upgradeable with some mods to Revision 4.

Added: 2018. July

Sparrow Lite prototype 0
Sparrow Lite prototype 1
Sparrow Lite prototype 2
Sparrow Lite prototype 3
Sparrow Lite Rev. 4. mod
Sparrow Lite Rev. 4.
Sparrow 48K Rev. 5.

Beta Disk Interface Great Britain Russia Czech Republic Slovakia Brazil

The system of British Technology Research Ltd. - similarly to another floppy disk systems – never became dominant in Europe in traditional sense. Despite of the fact, that in its time has very attractive parameters.

However, in two countries as Brazil and Soviet Union they almost exclusively were widespread as mass storages.

First version was the Beta Disk Interface (aka Beta-48) which came out to the market in 1984. Up to four units can be connected to it, 3, 3.5, and 5.25 inch ones (a: b: c: d: drive). One or two-sided, single or double density, 40 and 80-inch track disks can be used. Capacity of double-sided DD discs are 640K. Disk drives are powered via the interface.

Most notable innovations were the Magic and reset button beside the auto detection of parameters of floppy disks. The "Magic Button" saves the contents of RAM to disk.

In Brazil, this version became dominant. Several Beta-48 compatible interface existed in the country (CAS, CBI-95, AR-20, MID-185, IDS). Among them, nowadays Victor Trucco was choosen the IDS 2001 model to rebuild.

The German Midas company's product is Gammadisk, who further developed it with adding printer and Kempston joystick ports. Latter ones thanks due of the three-port 8255 PIO controllers. This interface uses the TR-DOS version 4.12. Also received an NMI button. A curiosity: the 27C256 EPROM has two pieces of 16K banks. A modified ZX ROM placed in the first, other has the TR-DOS, and first one remains hidden from the machine.

In 2015, also in Germany, Klaus-Peter Casper was reconstructed it again. On his website can be viewed the documentations needed for making one.

Beta-128 Disk Interface (or simply Beta-128) was developed for the 128K Spectrum. The 1987 novelty has retained its predecessor’s file format, but was not compatible due to changes in the ROM.

Reset button was disappeared, and replaced with a combined "system switch". Its middle position is the 48K mode, 128K is the right, and left is the 48K reset. In 128K mode, must use the own reset button of machine.

This was imported into the Soviet Union and manufactured from Russian parts. First Russian version of it was developed in 1989 by firm Option in St. Petersburg. First clone, which was used it was Leningrad in the same year. Soon they hacked the 5.xx original versions of TR-DOS and own 6.xx-ers have taken their place. But more about that later...

Beta-128 has become so de-facto standard, that it does not spread as a separate interface: on majority of clones was integrated into the motherboard (such as the Pentagon, Scorpion).

First TR-DOS programs were disc adaptation of classic games. So the 5-minute loading times were decreased to few seconds. Since capacity of disks were 640K (or using compression even more about 800K in case of games) it was common making thematic game compilations and by a menu can be chosen among them (arcade, sports etc compilations).

Next step was the rewriting the relatively large capacity PC DOS and Amiga games to Speccy (Prince of Persia, Ufo, Civilization). Some games fill up to two disks, Seasons of Sakura (16C) has three floppies! This was led to born of very high quality games. Such programs were released, from which even the press also wrote, that it is impossible to made their Speccy version.

Some companies have developed special Beta-128 interfaces of their clones. In the KAY 1024 found Nemo bus version already mentioned above. Peters company also come up with their own bus system to match the interface of their Contact clones. Some simplified versions only supports two disk drives, such as Scorpion. The new HD system has 1,7Mbyte capacity, although was did not widespread.

It was spoken about the cracking of original TR-DOS. Crackers were optimized code for faster operation and new functions have also been introduced in the system. This example is the aforementioned HD discs, the auto-boot, quick formatting and turbo loading - just to mention the most important ones. Latest version 6.10 (Mr. Gluk), 6.12 (Power of Sound) and vTR-DOS (developed for ATM clones).

Beside the TR-DOS; IS-DOS, Vision OS, DNA OS and a special version of CP/M can be the operating systems of the interface.

HR-DOS is the hacked version of TR-DOS. Interestingly, while the operating system was expanded by adding a printer utility - however, the code size is halved. Russian coders must know something!

Beta-128 was also cloned at the territory of the former Czechoslovakia, although it never reached such an outstanding success as the D40/D80.

Since originals are very difficult to obtain, for the request of Spectrum community Victor Trucco and Piotr Bugaj were reconstructed it.

Tetroid from from Novosibirsk was also constructed a small series of a Beta-128 clone.

Velesoft began a project too, that would have been a combination of Beta-128 with a real-time clock, an SD card reader, 512K SRAM and the same amount of FlashROM, which would have included the DivMMC routines as well.

Updated: 2016. August

Beta Disk Interface (Beta-48)
Gamma disk
IDS2001 clone
IDS2001 clone plus
Beta-128 Disk Interface
Beta-128 clone by Pavel Cejka
Beta-128 clone by Velesoft
Beta-128 Plus by Victor Trucco
Beta-128 clone by Piotr Bugaj


G. Shell

CDOS (Communication Data Operating System) is the second, not so widespread operating system in the ex-Soviet Union.

It name comes from CDOS interface, which is a modem+disc combo released in 1989. Beside the Spectrums, it is compatible with the American Timex 2048 clone too.

First version of CDOS operating system was a product of the firm Allegro in Moscow. Continuing the good-old Russian conventions, cracked and improved versions are rapidly appeared in Moscow, Saint Petersburg and Minsk (for example by KSA, Fantomassoft and MPR).

This interface is a multifunctional one. Beside the modem, it uses 5,25" or 3,5" 800K disks, even some versions contain 256K RAMdisk as well real time clock. If no built-in RAM found, it can use the own memory of the computer. Some versions equipped with Centronics port too.

Get bored loading your favourite utilies? Do not panic, CDOS also has 128K ROMdisk, to make these accesses really fast.

On the picture G. Shell. seen. Russians are not only copying the hardware, but the same can be said about software...

Most users only used the modem part of the interface, which was replaced to Hayes modems in most networks.

The very last CDOS network was SpbZXNet in Saint Petersburg, which was died in the end of 2002. Moscow and Minsk centres were died earlier.

D40/D80 (D40B/D80B)

D40 and D80 drives

D40 and D80 disk systems originally developed for the Didaktik machines. D40 uses 360K 5,25" disks, D80 is supporting 720K 3,5" ones. If really wanted, disks can be formatted up to 420 or 840K.

Quite clear, that the company is adopted the MS-DOS system, even the name of operating system is very similar: MDOS. After all, not surprising, floppy drives are standard IBM PC units. Drives can be connected directly to any 48K Spectrum with a ribbon cable, which contains a snapshot button.

Kompakt already has a built-in 3.5" D80 drive, one more D40B or D80B connectable for the machine (the name refers to the b: drive, they are without power supply types).

Only one drive must have external power supply, another can be a B-type. The manufacturer was tested them not only with original Spectrums and Didaktiks, but also with the ex-Jugoslavian Deltas.

MB-01/MB-02/MB-02+/MB-IDE 1.0-2.0-3.0/MB-03+ Ultimate/MB-02+IDE/MB-04 Slovakia Czech Republic Germany Netherlands

The history of interface goes back to the early 90’s. At that time decided MDV (Robert Letko - Robo) and Busy (Slavomir Labsky) it was time to develop a floppy interface for the Spectrum to replace the old cassette. At first, they only imagined a DD unit, and then the idea of a HD one was came up (as there was no such kind of interface for the microcomputers at this time).

However, the own CPU of the Spectrum was not enough powerful for this task. Therefore, a separate Z80-DMA circuit had to be designed, which was later also utilized as a graphics co-processor (‘the poor man's Blitter’). Finally, in 1992, the MB-01 was created with 2x64K battery-powered SRAM. There is no information about, how many MB-01s were born. The name is composed from the initials of the names of MDV and Busy, and the version number (01). By the way, it was originally named AP-01.

A Czech Spectrum-bros, Oldrich Palenicek and Jan Palenicek also became curious about the interface. They were so impressed, that they immediately wanted one. Busy was sent them to MDV, who gave them an upgraded version, the MB-02 (without the ‘plus’ sign). By the way, here are their long list of known aliases: Jackson Hollis/Jaxon Hollis/JSH Company Ltd. - Oldrich és Omega Software Graphics, Omega Computer Graphics, Omega Gfx, Omega, OSG, Omedron - Jan.

This interface was consisted of two smaller PCBs and was housed in a compact, homemade black box. It contained 128K SRAM powered by two AA batteries. The card was also included a memory slot (theoretically expandable up to 4 megabytes), Kempston and printer ports, and an NMI button. Otherwise, the handmade interface was fully compatible with the subsequent serial products, except for memory management. But since the BIOS and DOS were separated, this is not a major problem. Two pieces were made, owned by Busy and Omega. As stated on the PCB, was also made in 1992.

JSH was promoted the product at various events in the Czech Republic and Germany (for eg. Samcon 94/95, Zlicon 96) and he took it to 8 Bit Company in Zlin (after it, JSH was also active in the further promotion).

Here the development was professionalized. The implementation was done on a single large PCB, and a button cell battery powered the memory and now the optional real-time clock. This is the story, how the MB-02+ was born in 1995, the king of peripherals of the ZX Spectrum from this era (and also for the another 8 bit micros). Until December 16 of 2001, a total of 70 pieces were sold with its quite high price (310 DM). It was a professional quality, but handmade product.

Here are the detailed technical parameters. The capacity of disks are 1.8 megabytes with HD, and 840K in the case of DD floppy disks. Data transfer rates are 40-50K/sec and 25K/sec for the above mentioned types. Two drives can be connected at the same time, but with a dedicated hub, it can be up to four. The standard 128K SRAM can be used as RAMdisk, as drive 9 (no direct access possible).

There is a 2K EPROM in the interface, and the bidirectional paralell port was also integrated here. A Kempston joytick and Amiga mouse compatible combined connector was also included.

Its biggest advantage, that it is fully compatible with the cassette system. This way you do not have to write new loaders, just copy the files. Of course, as it is a Czech product, also compatible with the D80 system. This is done by the ed80 software emulator.

Its operating system is BS-DOS (named after Busy), which supports 256 directories and 65.279 files. The origins of BS-DOS and BS-ROM names now unnecessary to explain. DOS version is 3.08, 4.00 never released. It got a reset button beside to NMI.

In addition of original Spectrums, the manufacturer also tested it with the ex-Yugoslavian Deltas and Didaktik machines. Was even sold by Sintech in Germany.

MB-02+ is often cited as the pioneer of Multicolor and Multitech Monochrome modes.

Its several components was implemented by Velesoft in the modern era. The Z80-DMA circuit, originally described in Your Spectrum Magazine 1998/08-09, was redesigned in 2005 under the Data Gear name. Not only works with Spectrum, but also with other Z80 based machines (Scorpion, SAM Coupe). For faster machines, the DMA chip should be clocked at 6-8 MHz instead of 4. After the 2005 release, also produced a series in 2007.

The MB02-memory interface is the product of 2008. This is an MB-02 RAM disk compatible gadget with a total of 1 megabytes button cell battery supported RAM. It works in two modes: full 1 megabyte of RAM, or 512K RAM and 512K ROM. It works with any other interfaces, and has DivIDE compatible mode.

During its history, the MB-02+ got many hardware and software patches from the developers and fans.

One of the most notable is the Single chip 512K SRAM tuning made by Poke Studio (Petr Petyovsky - Petr, Poke or Pokestudio). Now we can have a comfortable, half megabyte, super-fast storage (January 05, 2006.)

The MB-02+ modification for 29C256 Flash PEROM and MB-02+ modification for 29C512 and 29C010 Flash PEROM are the innovations made by Last Monster (Jan Kucera - LMN/8BC) from 2000 and 2008. The former replaces the standard 2K 2716 EPROM with a rewritable 32K Flash PEROM 29C256, while for the latter, this size can be 64K or 128K (also divided into 32K banks). Branislav Bekes (z00m, Zoom) chose the EEPROM concept, he also uses a 32K version (MB-02+ modification for 28C256 EEPROM - 2013). Burning can be done with LNM’s own program, but z00m also made a slower one in case of compatibility issues may arose. By the way, you can read about it on the author’s Hw.speccy.cz website.

The next hardware upgrades, MB-IDE (1.0), MB-IDE 2.0 and MB-IDE 3.0 IDE controllers are also the developments of Last Monster. They are also known as MBIDE and MB-HDD. These are based on the internal ZX-IDE interface by PVL (Pavel Riha) and Tritolsoft (Lubomir Blaha). As the version number increased, the size of PCBs were became smaller and smaller and compatibility was improved. Dates of each version: 11 November 2002., 12 December 2005. and 20 April 2008. The size of the cards designed to fit comfortably into the enclosure of MB-02+. However, it can be used without the MB-02+, with a single Spectrum too.

Unfortunately, for booting from HDD, needed a floppy, which installs the winchester. To solve this, the MB-Maniax team (Logout - Martin Kukac, Shrek - Miroslav Bursa, Trixs - Vladimir Kristof) was developed an upgrade, called FlashBOOT (v1.: 26 November 2007). To accomplish this, we must implement on of the (E)EPROM expansions, since there is hardly fit anything into the factory 2K. Once this was done, flashing can started, and it is best to burn-in the other utilies, that can be used with the MB-02+.

Later, several other versions were created by this team of Czech and Slovakian Spectrum community (FlashBoot v1.1: 05 December 2007, v1.2: 08 December 2007, v1.3 aka JHCon version: 17 December 2007, v4: 23 August 2007).

In January of 2002, the first news from the successor, the MB-03(+) was leaked out. This was posted by Jan Werner (The Exterminator, Thorin, Wixet, Wixor/Total Computer Gang), one of the editors of Speccy.cz portal via the comp.sys.sinclair newsgroup. Specifications included 512-2048K SRAM, 32K FlashROM, PS2 keyboard and mouse connector, IDE interface and SD card reader.

So that would have been roughly the same as a tuned-up MB-02+. Most of the development costs emerged by the integrated circuit. Therefore, the price expected of 300 Euros (with a minimum of 50 pre-orders). Rumours were spread even about integrating the General Sound card...

The MB-03+ Ultimate project finally started in the spring of 2018. LNM tried to acquire practice in using Verilog, AutoCAD, Eagle and eventually chose this interface for this reason.

First phase was creation of an interface between the ZX Spectrun and the Xilinx Spartan 6 FGPA. To realize this, he was created the 01 LMN ZX Spectrum to FGPA interface board in June. Meanwhile, was turned out, that each Spectrum model works with different signal levels.

The next step was to simulate the ULA Beep part and the SAA1099 chip. Miguel Angel Rodriguez Jodar also helped with the latter. That’s how the 02 LMN Beep and SAA1099 board came out.

The subsequent implementation and testing of the 03 LMN MBIDE40 Compact Flash IDE interface board was still began in June.

At the beginning of next month, the first complete wire-free interface was created, the 4-layer 04 LMN MB-03+ Ultimate v0.0.

The implementation of the Preci-Bus (ie 05 LMN Expboard), a pin-based connector multiplying board, was the next step. Otherwise, the v0.0 worked well with MB-02+ and was compatible with all CF cards tested. The next step is the integration of Mikej’s (FGPAArcade.com) YM2149 emulation, enhanced with ACB stereo sound, as well Turbo Sound simulation. He was choose the DS3234 chip to implement the RTC. This was followed by further expanding of the sound section: Soundrive, Stereo Covox and the Czech D/A converters. Meanwhile, Andrew Owen was added the device to the ZXI standart. This is now currently maintained by ZX Design and Media (Chris Smith). The next step was the FGPA coding of the SD micro and CF adapter.

After v0.0 had done its testing job, he was started designing the next version with 8 megabytes of SRAM, 2 microSD and the same number of USB connectors. One USB is required for the firmware update, and the other is the Kempston mouse connector. By September, the 06 LMN MB-03+ Ultimate v1.0 with an ESP8244 Wi-Fi module was launched. The first task was to implement the Z80-DMA FGPA code, which had to be slightly modified for 128K+2A/B/+3 machines. After coding the SD interface, the board now works with microSD and CF cards. Garry Lanchaster has added a special version of ResiDOS. The designer also contacted Miguel Guerreio for a special version of esxDOS. The finished version uses DMA, so it is very fast. The device was debuted at the JHCon 2018 party.

On Christmas of 2018, he was started working on a new version with the Xilinx Spartan XC7S50 FGPA and FT2232HQ USB chips. Both DivIDE and DivMMC emulations were created with DMA support. As long as the 08 LMN MB-03+ v2.0 Ultimate card arrived, he was wrote the Kempston Mouse code. The Memory LED map of z00m and Busy was also implemented on the interface. This version was introduced at the Forever party. Meanwhile, the new version of esxDOS already supported long filenames. Development of a new version of BS-DOS has also begun. In April 2019, General Sound emulation was also implemented. The digital video output was functional by the end of June.

And with the 10 LMN Expboard, it is possible to place both horizontally and vertically the 10x10 cm 09 LMN MB-03+ Ultimate v3.0, which is based on v2.0.

First nine test boards were arrived in May and only one of them worked. This one got the first serial number. By the end of June, the first tests of HDMI digital video output had also begun.

The beta version of the case was completed in early July next month. At the end of this month, the working boards were arrived (MB-03+ Ultimate v3.1), and fitted into a slightly modified case. Shrek has created three utilities for Wi-Fi. Wifi Connetction is connecting to the hotspot and Time Sync synchronizes the real-time clock. With Software Updater it is possible to download MB-02+/MB-03+ utilities from a repo.

By mid-October, BS-DOS 3.08b was made by z00m, EasyHDD 207 utility was also released, and AY and RTC72421 emulation were also improved. The algorithm which belongs to the LCU process, and required for accelerated video processing for class A (2560 × 1600), B (1920 × 1080), C (832 × 480), and D (416 × 240 pixels) resultions, was designed and coded by LMN.

The system was also tested and worked with UNO DOS, originally designed for ZX-Uno and DivMMC (October 22). By the end of this month, the case had undergone a minor facelift.

November and December went by with the improvement of digital video output.

This was continued into the New Year, mostly by coding the BIOS/setup of the video firmware to be compatible with the different clones. The setting possibilities of the LED matrix display have also been refined.

Thanks to the two-month coding, the especially timing-critical border and multicolor effects also appeared pefectly at 720x576p/50Hz, so compatible with most TV sets.

From here was begun the implementation of the extra graphics modes, GigaScreen was the first to appear.

It was then also possible to use custom ROMs: 16K, 16/64K and 64K pageable ones.

Newer graphics modes include ULAPlus, TIMEX Hi-Color, Timex Hi-Res, and the latter also works with SE Basic v4. Also possible to use the GigaScreen and Timex modes together (Multigigascreen and Timex TC2144/TC2128 Hi-Res Gigascreen).

The simulation of scanline effect can be changed in 8 steps.

Compatibility testing with the ZX Next began in mid-March and was completed in April, also became possible to use all audio features together.

In addition to the original Spectrums and Next, with Just Speccy 128K, Harlequin 128 2D and Karabas Nano rev. C clones was also tested.

In May, development of new programs were also started. With Milan Strava’s (Hood) Wifi Download Utility you can download and run programs from a remote server. Vladislav Rivnyj (NEO Spectruman) started to working on a SID player. Also in this month, HDMI audio was realized with a FIR low pass filter. The speed of the UART was also increased. Turbo Sound FM has also been implemented and esxDOS version 0.8.8 was released before the summer.

Back in time! In 2007 most of the MB-02+’s enhancements were integrated by the German Ingo Truppel’s MB-02+IDE interface. Of course, it is compatible with the original, as it is based on its circuit. But became much smaller, because Ingo realized it on a four-layer PCB.

Kempston and Centronics ports were built-in, along with the real-time clock. It comes with 512K RAM by default. Its most important innovation, of course the IDE interface, which also supports Compact Flash cards (Ingo made his own CF-IDE adapter). Reset and NMI buttons, as well as 2 LEDS, the power and IDE are also present here.

There were also news from the Netherlands in 2007 about the enhancements of the interface. Ben Versteeg has been working on the MB-04. 512K RAM, Z80-DMA, IDE interface, CF-IDE adapter, mouse and keyboard connectors were all included in this design.

Apart from a few features, the prototype also worked with 128K+2 and +2A machines. Ben would have split into two the final version of the printed circuit board: planned to integrate the Z80-DMA, the mouse and keyboard controller into the first circuit. Another components would be located on the second card, which is connected to the first by a ribbon cable. Since Ingo Truppel came up with his own interface, development was stopped.

One of the manufacturer of the soon described DivIDE, the Jaroslav Smetak, (Noby), was also planned to re-launch the MB-02+. However, since its assembly takes twice as much time as a DivIDE, Noby eventually dropped the idea of resurrecting of MB-02+. The modern price would be between 120-150 Euros.

Noby is also taking part with Noby Noblnoch, Aragorn, Jardasoft aliases in works of the CI5 The Amaters, Naughty Crew and Gemba Boys teams.

Frissítve: 2020. május

MB-02+ prototype v1.0 and 2.0
Data Gear 2007
MB-02 memory
Single chip 512K SRAM tuning
mod for 29C512 and 29C010 EEPROM
mod for 28C256 EEPROM
MB-IDE 1.0
MB-IDE 2.0
MB-IDE 3.0
MB-03+Ultimate v3.0
MB-02+IDE prototype
MB-04 prototype


SMUC v2 rev A

Scorpion's solution for combining the ZX Spectrum with hard disks was the SMUC (Scorpion and Moa Universal Controller) IDE-controller. In its name it is refers to Andrew Moa, who was the co-developer of this card inline with Scorpion.

Two HDDs can be attached to the card, just like to as its PC-ancestors. You have to copy the original TR-DOS disks track-by-track onto the hard disks. It works with up to 4 "virtual" Beta-128 drives - a:, b:, c: and d: disks (in a very similar way, as you use a software ZX Spectrum emulator).

SMUC is compatible with TR-DOS, IS-DOS and a special version of CP/M operating system.

2K NVRAM is fitted as standard on the board for storing the tuning-settings as well the datas of HDDs. Real time clock is also easy to install for the SMUC. Just plug the Dallas DS1287 chip into the prepared slot and it will work. Many other PC-compatible peripherals also connectable for the SMUC, for example Hayes-modem.

As Scorpion’s stocks were sold out, members of zx.pk.ru decided to create a similar universal controller with backward compatibility to the original (SMUC v1.3). It got new name, which has the same abbreviation: Spectrum Multi Unit Controller v2.0 rev A.

With the card, not only winchesters, but also CDs/DVDs, CF-cards (with adapter) can be connected to the computer.

Compatible with the followings: KAY-1024, Scorpion, Pentagon 1024, ZXM-Phoenix.

Can be ordered from Witchcract Creative Group.

Updated: 2010. January 16.

NemoIDE (Nemo IDE) Russia

For controlling hard drives and CD-ROMs, Nemo has also developed his own IDE interface in 1996. It got the Nemo IDE name (or alternatively called NemoIDE) and was based on the 1994 prototype of Nikolay Tyrsin (Iskra Soft Ltd, Leningrad). Originally, of course made for KAY clones, but because of the simplicity of circuit, quickly reenginered for Pentagon, Scorpion and Profi etc. machines as well.

Briefly about its operating system, the iS-DOS. Between 1990 and 1992 was developed by the aforementioned Iskra Soft Ltd. It supports DS/DD floppy disks, CD-ROMs and hard disks. For the latter, it uses maximum 16Mbyte partitions.

The system was born as an alternative of TR-DOS. It aims was to eliminate its disadvantages, such as the lack of subdirectories, the maximum 64K file size limit, and the maximum number of 128 files.

That’s why, the system was developed on the base of MS-DOS. Was also included a built-in Norton Commander-like file manager and several utilities.

Its main disadvantage, that it was not TR-DOS-compatible and memory management was limited because it works from RAM opposed to TR-DOS. So occupies a valuable part from the lower memory. Extended memory management was later resolved in TASiS.

But its main benefit was, that with drivers able to handle a wide variety of extensions (eg. expanded memory and various other devices).

Take a look at the major versions.

IS-DOS '99 Classic is for 48K TR-DOS machines.

When booting iS-DOS '99 Chic, it turns off the BASIC ROM and works as a "shadow RAM". In the case of KAY, ATM Turbo 2+, Scorpion and Profi clones, it also leaves more lower memory available. Expanded memory can be even used as RAM disk.

IS-DOS'2000 is already SMUC compatible on Scorpion clones.

TASiS (Text Alternative Screen iS-DOS) is the development of NedoPC group for ATM Turbo 2+ from 2006 and it is based on Chic. Authors are Yuri Korsunin, who wrote the kernel and drivers, as well Timonin Maksim Anatolevic (ie Maksagor), who was made the software development, and take part in popularization and distribution of the system package. The system handles the text mode and also the extended memory.

The associated xBIOS ROM firmware also resolves TR-DOS compatibility. It is because includes vTR-DOS, which simulates TR-DOS at the system level (for example, it is possible to copy the contents of floppy disk into the expanded memory). The package is freeware.

IS-DOS was initially distributed by the Moscow located Slot Ltd. in the 90's and also by iS-DOS Support Team in the Saratov Oblast region. Nemo had been involved in the distribution until his company ceased.

Mr. Gluk was also made a hacked version of TR-DOS 5.30, which supports IDE devices using together with DNA OS.

Now back to the hardware itself. Of course, the interface uses Nemo's ZX Bus. Since the circuit diagram is public domain and originally was rather buggy, many people was further developed it.

NedoPC group, the developers of TASiS, also produced their own version, which was made from 2004 to 2006. Its developer was Andrey Lazarev (iNSIDE). A 2005 version of it was also available by Perspective Group.

Z-Controller-above its offered extra functions- using the NemoIDE for controlling IDE devices.

Witchcract Creative Group also comes up with its own version, which already supports the Pentagon 1204SL and ZXM-Phoenix machines beside KAY and Scorpion ones.

In 2010, when the KAY clone was reconstructed, zst was reproduced it with ZXkit-011 name.

Update: 2018. October

NemoIDE by NedoPC
Z-Controller v1.0
NemoIDE by WCG
NemoIDE by Alex Nemo (aka ZXkit-011)
DivIDE and its clones as well its further developments Serbia Czech Republic Slovakia Germany Poland Great Britain Netherlands Italy Brazil Russia Portugal

DivIDE -as the name suggest- is an IDE interface originated from the Czech Republic. So far this is the only device in the 'new age', which became some kind of de facto standard interface internationally.

Before getting know about the interface, let's begin with its pre-history.

The ZX-IDE interface is the joint development of PVL and Tritolsoft from 1999. This one is an internal variant, which is also the first version of MB-HDD built into the MB-02+.

For the authors, Matsoft (Matej Kryndler) brought the Serbian Pera Putnik's interface diagram downloaded from the Net. Its main problem was since the IDE HDD is a 16 bit device, and the Speccy is 8 bit, therefore the capacity of hard disk will automatically half of the nominal. So, the single I/O channel has been replaced to a six channel I/O structure. With this, and a special backup method, the full capacity can be used. The interface can handle two IDE devices (master and slave) at once.

The MB-02+ compatibility was solved by dR0n (Jiri Slezka). With the HDD_patch utility 2 megabytes of virtual disks are used. Later version of the program is also supports LBA and DMA modes.

The next step is the external version of ZX-IDE interface prototype, which was never released to public. Busy has also helped in its implementation in optimizing of reading and writing operations. 64K EPROM, 128K battery backed SRAM and an NMI button were the main new features.

In 2002 February released the wired prototype of DivIDE 42r2 from Zilog (Zilogator, Pavel Cimbal, xcimbal). This was mainly based on the ZX-IDE interface, but returned to Pera Putnik's more primitive read-write operations. Contained 8K ROM and 32K RAM memory.

The first public version was DivIDE 57, mostly spread among the Czech colleagues from August 2002. Worth to mention, that Cimbal was made it without any testing, so made the first one from scratch – and it was working.

This was followed by DivIDE 57b, in which the IDE connector and NMI button was moved to a better position (aka 'facelift').

The most widespread model, DivIDE 57c is the same, but on the board the jumpers are signed with different characters. It has some electronic modifications. Also can be ordered the whole stuff from Divide.cz webshop, which is ran by Factor6 (Alan Petrik), Noby (Noby Nobloch) and Baze (Milos Bazelides). It is available in two quality: with standart or precision chip cap. Last one is equipped with blue LED. Those who are affraid to order from an ex-socialist country, can order it from Sintech located in Germany.

Was made 20-20 pieces from each series.

In order to eliminate the shortcomings of original DivIDE, the Polish Jarek Adamski and Jurek Dudek constructed the DiwIDE interface.

Although the original developers of the card were upset, they agreed in the fact, that DivIDE needs further improvements. Mainly it was necessary to enlarge the memory to fit inside the more complex operating systems.

DiwIDE v212 was the first public testversion. It was contain 32K EPROM, 128 or 512K battery backed SRAM. The CF connector was existed as only as an option, but the Sinclair thoroughgoing connector was already integrated by Jarek.

DiwIDE v317 or alternatively DivIDE Plus was the final release. Contains 512K ROM and 512K RAM onboard and has DivIDE and MB-02+ compatible modes. Also integrated a Compact Flash connector by default. The card incorporates six operating systems: the original FATware, ResiDOS, +DivIDE, DEFMIR, MDOS3 and TBIOS. In the future expected the support of CP/M and ZXVGS. Minimum exits in two subgenerations: as a green and a red coloured PCB.

The interface is sold by the English RWAP Software with DivIDE Plus name.

The upgrade of Velesoft, DivIDE 512 contains 512K SRAM and 128K ROM. It works with SD card as default (by an IDE/SD adapter) Additionally, the whole stuff is boxed onto a neat black plastic case. Have two modes: a DivIDE compatible, and the 'allram' mode, which is similar to the R"GAL tuning. RAM also can be write-protected. For realization the original 28 pin chip-mounting have to be replaced with a 32 pin one. Noby also helped in its creation. Release date: 2008. July 09.

DivMMC an open standard. It was developed by the Italian Mario Prato, from who we can know about the Chrome clone. Main features are the dual SD card connector, NMI and optionally a reset button and 128K Flash ROM, which can be easily expanded to 512K. In 2013 saw the light. Its name comes from joining Divide and ZXMMC +, indicating, that with both are compatible.

The Polish Piotr Bugaj's (Zaxon) cards is based on this too. First got the simple DivMMC name. MicroSD, 8K ROM, 512K RAM, NMI and reset are the main features. The missing Kempston port can be added with a mini-port expansion card or can be connectd through the edge connector with a Kempston joy interface. PicoDivSD is the minimalist version of it, without expansion port, edge connector and reset. It is preferred to use with the post-128K Spectrums, since they have factory joy port and reset button. Next one is DivSD Nano, which a bit bigger compared to pico, so more easy to de-attach from the 128K Spectrum. The reset was also fitted again.

The Dutch Ben Versteeg was also produced DivIDE 57c clones. His current development is the DivMMC EnJoy! Interface Series, which is available from 2013 onwards. This is a further development of Prato's work. Instead of Flash ROM, 128K RAM was added, which can also be easily expanded to 512K.

The first version is the standard DivMMC EnJoy!, which comes with EsxDOS pre-installed on a 4Gb SD card with FAT and FAT32 support. Its main advantage of compatibility with all factory-made Spectrums, which can be set with DIP switches. Has integrated Kempston joystick connector as well NMI and reset button.

DivMMC EnJoy! * mini * is the same without the Kempston interface.

DivMMC EnJoy! * duo * is doubling the original possibilities in two cases. The joy interface is now compatible with Kempstion and Sinclair and has two SD card slots.

DivMMC EnJoy! * pro one * also offers a thoroughgoing edge connector and offers Investronica and + 3e compatibility. ZX-compatibilty modes are automatically detected without any switches.

The Polish Lotharek also offered DivIDE 57c clones. The first bunch from 2009 is red, the second series of 57c clone is purple from 2010. His own development is the DivIDE 2k11 (DivIDE 57c2?). This is fully compatible with 57c, but due to the CPLD, further (firmware) expansions are possible. As it is a newer design, the card is also smaller size compared to the original. DivIDE 2k14 (or alternatively DivIDE 57c3) also CPLD based and differs from its predecessor from a joystick port. It can be configured as Kempston or Sinclair. Has place for four flashable firmwares and power consumption also reduced by using SMD components.

Ewgeny7 used as a starting point the DivIDE 57c to develop the Russain-clone compatible MultiIDE. This has already a ZX-Bus connector. The most important innovation is the Flash memory module, in which simultaneously 8 operating system can be placed in. Selection from them is done by jumpers. Who want to order, can do it through zst's homepage, he will send his usual blue coloured expansion card.

The DivIDE 57d series from 2012 is the result of Czech-Brazilian co-operation. Victor Trucco was sent his friend's (Alexandre Colella) TK clone to Velesoft to find out the reason of incompatibility. Only in two places had to change interface. The pin 4 (Sound in) only have to be deactivated, so to be cut through. The number 16 one (Mreq) have to lift up, and connect a thoroughgoing resistor. Rui Picanco was suggested to enhance the modding with to be made switchable the pin 4 with a jumper, since it uses the ROM1OE signal in the case of post-128K+2 Spectrums.

So after the modding of original 57c, they made three series in which with a jumper can be set the TK-compatible mode. There are several subversions: 57d blue for Brazilian users, 57d2 green for Czech colleagues, and purple 57d3 for the members of World of Spectrum forum. Other improvements include: signal strength, and ZX and IDE reset button. The HDD AC power connector has been replaced with the connector of IDE adapters.

Later Velesoft was further developed these also with 57d4 name. It got better bus signal booster. 57d3 got a new joystick interface PCB also.

On the summer of 2014 the RTC module for DivIDE was born again from Velesoft. It is compatible with 57b, c, d1, d2 and d3 cards. With the RTC72421A or RTC72421B chips it handles the time attribute of files under the ESXDOS operating system with FAT16 and 32 file systems. Of course, it needs an CR1620 battery to do this. It contains a double output multi-functional Kempston joystick port, to which the mouse of Commorodre 64 and Amiga could connected, as well the controller pad of 8 and 16 Sega consoles. It can be also used as bi-directional serial communication port. It is possible to use the original 8K EEPROM, and 4 different operating system. We can choose among them from the 32K AT28C256 EEPROM. For installing the card, need to be plug it into the socket of M-GAL and original EEPROM chips, and after put these chips back onto the PCB.

DivIDE is compatible with all ATA devices including HDDs, CDs/DVDs and CF cards (the last option is the most popular among the users).

Data transfer speed is 218K/sec and the full capacity of ATA devices useable. Compatible with all Spectrum variants and clones.

Let's see the operating systems of DivIDE. FATware is the development of Baze. Supports eight FAT16 partitions with long filenames. It handles TAP, SNA, Z80 as well normal and interlaced SCR files. It reads on the fly the files copied on a PC to the Compact Flash card when it is plugged into the DivIDE. Unfortunately, can not write onto it, this feature was planned, but seems unfinished. Last official version is v0.14 from 2011. Several patches are exists, Velesoft and (Micky) Michal Tarasiejski made them with the agreement of the author.

ESXDOS is the firmware of Papaya Dezign. It is the work of LaesQ, L.A.Esq, who’s real name is Neil Laws (Great Britain) and Phoenix (Portugal). Has full support of FAT 16/32 file systems without extended partitions, long file names and 64K cluster support (they are planned). In case of DivIDE, supports HDD/CDROM/ZIP/LS120, for DivMMC supports MC/SD/SDHC devices. These are controlled by drivers. Also has TR-DOS, +3DOS and cassette emulation. Last official version is ESXDOS 0.8.5. Aside Velesoft, UB880D made patches and add-ons for it.

DEMFIR (DTP's Emulator Files Runner) is using the ISO 9660 file system of CD-ROMs with long file names. Beside of real discs also can handle their ISO image files. It detecting the IDE devices, then automatically boots from CD-ROM. In case of other IDE devices, if there is an ISO file at the beginning of the medium, it can automatically load it, otherwise should start manual search. TAP, TZX, SNA, Z80, MFC, SCR and POK files are supported, of course only can read them, not able to write. Last version is d0.7b, which was released on JHcon 2006 party. Meanwhile Velesoft and Zilog modified it. Responsibles of the project: Michal Jurica (Mike/ZT, mikezt), Tritol and UB880D.

For the latter two operating systems appeared z00m’s DISO image file (utilities?). But the ESXDOS one is only a reduced version.

For to the ex-Didaktik owners was born the MDOS3. It uses virtual D40/D80 disc images, and can handle total of 4 of them. It is the development of CI5 the amateurs team, which was also introduced the MD3 file extension at the same time (virtual disks). Capable of emulating the tape recorder also. Coders: Sweet and MTs, English-language document translation: Jakub Chalupnik, Martin Kukac (Logout) and mikezt. Latest version from 2010. There is also exists an MDOS3 tool suite, this was created by Dizzy between 2005 and 2007. As a continuation, released the MDOS TOOLS - Project 2 and Project 3, which work is from 2010 by MTs.

MDOS 2.1 is a ROM modding for Didaktik Kompakts, using the same MD3 extension. Was made by MTs.

+DivIDE is the adaptation of the GDOS/G+DOS operating systems found in DISCiPLE and +D disk interfaces, the work of the Dutch Rudy Biesma from 2005. Compatible with all software, which are not using the GDOS/G+DOS ROM calls directly. Uses 1600 sector disks on IDE devices in LBA mode (800 Kb, 2 sides, 80 tracks, 10 sectors and 512 bytes per tracks).

Scott-Falk Hühn was released the +divide Manager Windows-based program, with which can manipulate the virtual disks via graphical interface in an easy way.

BS-DOS 3.09 is the update of BS-DOS 3.08 operating system made for MB-02+ by Busy. It using 2 megabytes of virtual floppy disks, from which maximum 255 pieces can be used (MBD files). The old floppy BIOS was updated with an IDE BIOS. Was born more versions, later ones are bugfixed and supporting the NMI function (August 2009). Beside Busy, name of Dusky is worth to mention, since he was coding the IDE BIOS. And Z00m was created its installer. Only compatible with old R”GAL modded DivIDE interfaces, but also supports the allram mode.

Two new BIOSes were also published. TBIOS basically a hardware testing suite, useful for those, who like tinkering and for example build the interface for themselves. The source code is available, in order that the developers understand how handled the ATA interface, the shadow ROM etc. Final version is v1.4 from 2003 and the work of Zilog.

Velesoft BIOS is a new BIOS for the interfaces from 2011. After downloading the appropriate files, needs to be re-burned the EEPROM. Capable of handling 2 megabytes of virtual memory with boot menu. This is quite large space enough for many things. Also compatible with DivIDE Plus version.

Goldfinch (Gasware) is an aborted project from Gasman (Matt Westcott). Last time it was updated in September 2008. This contains an .scr viewer and writer as well a .tap and reader and writer. For accessing FAT16 file system uses Garry Lancaster’s FATfs system from ResiDOS. Low-level DivIDE ruotines are derived from Fatware. The system is using Paul van der Laan’s Clairsys font, which is a modified of the original one with some enhancements. Its size is only 6 kilobytes, half of this is code and half is empty buffer, so in theory it could been even firmware.

Garry Lancaster’s ResiDOS operating system also supports DivIDE+ and Velesoft’s DivIDE 512 card.

Velesoft also began writing of the quite funny called TRD-OS operating system, which he was eventually stopped. Participated in this 2008 development Hood as well.

What we can know about it, that based on the operating systems of MB-02+ BS-DOS and Profi clone, and can handle four virtual disks up to 1 megabytes. Source codes are still there ...

Updated: 2016. October

ZX-IDE internal
ZX-IDE external
DivIDE 57c
DivIDE Plus
DivMMC (by Prato)
DivMMC EnJoy!
DivMMC (by Zaxon)
DivIDE 2k14
TK compatible modding of DivIDE 57c v1
TK compatible modding of DivIDE 57c v2
DivIDE 57d
DivIDE 57d2
DivIDE 57d3
Joystick module for DivIDE 57d3
RTC module for DivIDE 57x

Megadrive 256

Megadrive 256 v1.0

Tnt23's (Tim Tashpulatov) SD card floppy emulator is named Megadrive 256. Amiga owners also know as Amiga Floppy Emulator. This is only partially covers the reality, as also compatible with ZX/TR-DOS, Atari ST, and MSX disks.

The prototype (…) was followed by the yellow coloured PCB Megadrive 128. Then the 'green' Megadrive 256 v1.0 and v1.1 was released.

The card could get fancy green, white or yellow coloured LCD, and floppy sound is simulated by a mini piezo speaker. The onboard memory is represented by an antique 4/8 megabytes SIMM module, here will be loaded the floppy image files from SD card.

It takes approximately 15-20 seconds, for the compresses formats (for example Atari ST) this time is increased by the unpacking time. In case of TR-DOS disks, this time is 16 seconds. We can navigate in the menus of alphanumerical display with five buttons.

About the mass storage devices: SD cards supporting the FAT32 file system, tnt23 tested maximum 2Gb ones (long file names and using of subdirectories are supported).

The IDE connector is 'officially not supported'. Although the designer tested it some old CF cards and HDDs, decided not to focus on IDE functions (therefore not ever card has the IDE connector soldered).

HcX Floppy Emulator

France Poland

USB HxC Floppy Emulator

The idea of HxC Floppy Emulator appeared on early 2006. Jean-Francois Del Nero (jfdn, Jeff, HxC, HxC2001) as an Amiga and Atari ST fan would like to use his old machines, but without the old, annoying floppies. Then was born the first prototype of HxC, which is connected via the parallel port to a PC. On the 'another end of the line' was the 34 pin floppy connector of the Amiga or Atari. Between them the TTL-based converting device, the emulator card.

On 2006. December 08. saw the light the enhanced version, which is built around the Altera CPLD, and the parallel socket was changed to an USB 1.1 one. Hence its name is: USB HxC Floppy Emulator. The PCB is available in two versions: Rev B is a homebrew one, and Rev C is a professional, two-layer construction.

Among the classical micros, usable on ZX Spectrum +3/+2A/B computers. It handles the .DSK, extended .DSK format (read-only, special image file). The best thing is the support of .TRD and .SCL files, so new Russian programs will run on a traditional micro.

On 2007. April 05. was born the HxC Floppy Emulator SDCard FGPA-based prototype.

Then, on 2007. December 22., the SDCard HxC Floppy Emulator, built with the PIC18F MCU and alphanumerical display, which is Jean's last development. This supports SD cards up to 2Gb and SDHC cards up to 32Gb with about 500K/sec data transfer speed.

Using the FAT32 file system, support of long file names and subdirectory structure is also solved. Anyway, the same disk image formats are supported as in the case of USB version.

The professional quality version of this interface manufactured by the Polish Lotharek since 2010 March 13., which is made on his usual, red-coloured PCBs. It has detachable display, 3 LEDs and 3 buttons (next, back, eject) and a small speaker. Otherwise, the USB-version also can be ordered from him, and from several (independent) producers also distributing the USB-version.

Weblink: HIÁNYZIK!!!!! Galéria:
SDCard HxC
USB HxC by Lotharek
SDCard HxC by Lotharek

ZX Tapper Russia

The development of Trolsoft (Oleg Trifonov) from 2015, ZX Tapper is a cassette unit replacement periphery, which using SD/SDHC cards for data storage.

It works with Atmega 128 microcontroller, its 16MHz speed and other capacities are sufficient for future developments. Navigation is done by a Nokia 5110 display and a 5-button joystick. Real-time clock can be either PCF8583T or PCF8563T.

The speaker with adjustable volume allows you to monitor playback and recording via two jack connectors.

In November 2017, version 1.4 was released with a 128x128 resolution color screen. The latest firmware already supports .TZX files along with the standard .TAP ones. It is also possible to upgrade the firmware from an SD card. It has already closed source and encrypted in order to prevent piracy, assigning the firmware serial number to the serial number of the cards.

Added: 2019. March

ZX Tapper v1.0
ZX Tapper v1.4

ZX Taper Poland

Klaudiusz Fatla's (Klaud) ZX Taper periphery (the name of the prototype: TZXC90) is based on the first version of ZX Tapper. Its firmware versisons from 1.1.3 to 1.1.6 can be used for it. Beside the original 48K Spectrums, was tested with Timex Computer 2048, Harlequin 48K rev. G and Chrome 128 Issue 3B.

Two moddings also came to light for the device. The first combines the load/save functions with a single cable using a stereo jack, just like in the case of ZX Spectrum 128K+3. The mic connector can be omitted in this case, but if it is retained, it will work properly.

The second modding improves the reliability of saving by cutting off frequencies that are unnecessary for the function. This requires the insertion of a 4.7nF (0805) condenser.

If you want to apply the above mentined two changes together, you need to choose a 10nF capacitor.

ZX Taper 1.1 version 1.1 already includes both changes.

Its 1.16a and 1.16b firmwares are the development of the Speccy.pl community. The first one is the English and Polish translation and improves handling the mechanical lock of the SD card, the latter bring the a novelty in the layout of the keypad.

Added: 2019. March

ZX Taper


The ZXMMC interface was born during the development of ZX-Badaloc clone, so its father is the same Alessandro Poppi, whom we met there. This is an SD/MMC card interface, which is placed into the Z80 slot. Originally was designed for the Amstrad produced Spectrums. In theory, compatible with all Spectrum, but inserting suffers physical limitations. In fact, can compatible with any Z80-based machine.

Baud rate is 218KB/sec, similar to Divide because of hardware and software limitations. Supports two memory cards, but in case of the basic version, only soldered a single socket.

The basic version was built with the Xilinx CPLD XC9536XL. The full version with the XC9572XL, and Kempston joystick and RS-232 ports were also integrated into it. In any case, it can be retrofitted for the basic model as a separate circuit called SerialSucker.

Its further development the similarly Xilinx XC9572XL based ZXMMC+, which offers Interface I compatible network capability, just like the RS-232 section. Got 512K battery backed RAM, and the same amount of FlashROM.

This one is compatible with all Spectrums, as it have to be connected to the edge connector, and itself also contains such thoroughgoing port. NMI and reset buttons were also seating next to the dual card slot.

Pino Giaquinto was also designed an USB adapater card, replacing the RS-232 port. It can be useful nowadays, as the new PCs usually do not have serial port. The mini-circuit must be plugged into the place of original serial port, fully fits into it. Includes only two pieces of ICs, their operating is indicated by two LEDs. On the enhanced, Issue 1a board only changed the place of components.

In both cases, can be used the ResiDOS as operating system. For ZXMMC, the version made for ZX-Badaloc should be used. The plus one has a separate version available.

USB Interface for ZXMMC+

ZX Dandanator! Mini Spain

ZX Dandanator! Mini is an 512K EEPROM cartridge, the creation of the Spanish Dandare. Its aim was to create a peripheral device, which helps the console-like game development. In addition, of course, it supports 48K and 128K compressed and uncompressed .Z80, .SNA and 48K .TAP files and using of alternative (for example test) ROMs.

Its additional features the poke/trainer with .POK files, software compression, screen pause and Ramjet 3 emulation. Through the Spectrum EAR connector, a serial port or DivIDE-like card can be loaded the programs into it.

Key features are the 512K memory, which allows the use of multilevel loading programs, turning into a video console the Spectrum. Starting from 2.0 version contains a Kempston joystick port too. Compatible with all members of the ZX Spectrum series, in addition also with Harlequin, Timex Sinclair 2048/2068, the TK90/95, Invest Spectrum and Just Speccy 128 with in the latter case the inner DivSD is deactivated.

It includes a through edge connector, so works great with another devices. On the first hand, can be deactivated without disconnecting, and the other hand, and it can automatically shut down itself, if a peripheral using the ROM address.

Capabilities of the card is demonstrated in the Ianna Sword game.

The project was started in March 2016, with the in collaboration of Spanish Speccy community. In May was completed, and in the next month was ready for posting the first version of the card, component, boxing combo. After another month, the second version was also born.

All documents are public domain, so anyone can build it freely, but can also be ordered through the author's website - in this case, of course, it is expected some turnaround time as well.

Updated: 2017. January

ZX Dandanator! Mini v1.0
ZX Dandanator! Mini v2.0

Interface 1bis South Africa
Dan Antohi has been developing his Interface 1bis card in South Africa since 1994, so it is reaches the Version 4b number now. It is (backward) compatible with the Interface 1 at the level of Microdrive commands. The RS-232 and ZX-Net was not fully implemented, as they have quite limited possibilities and became obsolete during the years.

The 'M' drive can be a maximum 128Gb capacity SD card split into 32 megabyte partitions. Also there is a possibility to connect it to a PC through an USB port and we can use its shared drive as letter 'V'. No maximum size limit is here. These are the possibilities of handling of the .TAP, .Z80 and .SCR files.

On the card clearly visible the nearly two decades long development. Its main features the double layer PCB with CPLD, and the very robust, overbuilt finalization.

It also has Kempston Joystick and PS/2 mouse ports. The last can be Kempston mouse or Joystick compatible.

First version (Version 1a) saw the light in 1994. This was a expansible card with four fully buffered expansion slots.

The whole thing is placed into an Atari Gameselex box, and the card itself was made on an Apple II prototype card. Memory could be 32, 128 or 512K SRAM chips, accessible as maximum three 128K RAMdisk.

It had Centronics and Kempston Joystick ports. The operating system is burnt into the shadow ROM. It emulates the original Interface 1 (of course the previously mentioned ZX-Net and RS-232 excepted), and also contains a 32/64 column printer driver.

Version 1b was appeared four years later. The PIO mode IDE controller was built on a separate ISA XT prototype card. It was introduced the virtual 32 megabytes Microdrive support. Also it was the very first time realization of the client-server connection, of course using the parallel port for connecting the 'V' drive at this time.

In 2002 released an IDE controller for the Z80-based machines, which was crunched into a 36 macrocell CPLD - this was an intermediate step for the further development.

In 2004, with Version 2a, the interface was integrated into a 72 macrocell CPLD, which now was fit into a Multicomp MB3 box, while retaining its full functionality.

Between 2005 and 2008 (Version 2b-2e) was the period of memory optimization (shadow ROM, memory area and puffer).

In year 2009, in the case of Version 2f, five input and output lines replaced the grounding lines. So from this time we can speak about streaming parallel port, which works with 8 input and output, as well 4 control ports for the communication.

Again in 2009 saw the light the Parallel Port peripheral too. This is an MCU-based device, which is connected to the parallel port and gives RS-232, USB 2.0 and 12MHz SPI port support. In the same time, the drivers also written for the device.

After another one year, the support of SD card also realized by the previously mentioned SPI port. At the same time, the file system of SD and HDD was also improved.

Again, in the same year, another module was born, which named to System Bus peripheral. As its name suggests, directly connected to the system bus. Also an MCU-based device, and supports SD-card, USB, Kempston Joystick and Kempston Mouse (PS/2) ports.

Version 2g-i is the fruit of the same year, at this time the above mentioned module was improved.

The next variant from 2011 was Version 3a. At this time, the interface and the winchester together were integrated into a Dk'tronics house. Parallel port was eliminated. Meanwhile, the modern USB and micro-SD card ports integrated. At the same time, the size of the card became more and more compact and got a 'real' power supply instead of the dead Spectrum's power unit.

In 2012 in order to prepare the small number series production, the IDE port was cut off with Version 4a. So now the logic of the card was fitted into a 36 macrocell CPLD.

After a year, with Version 4b, the RAM drive option was also deleted. In that way, only 32K SRAM necessary for the card, and six I/O lines were freed up. The PCB got a voltage regulator circuit, which now measures 100x49,5 mm and it is two layered. The possibilities of the (small) series production now ready, first units were came out in January of 2013.

Interface 1bis version 1b
Interface 1bis version 2i
Paralell Port Peripheral
System Bus Peripheral
Interface 1bis version 3a
Interface 1bis version 4a
Interface 1bis version 4b

Z-Controller Russia

Z-Controller is also King of Evil's inventment, the guy with the Pentagon 1024SL computer. This one is a really universal too: we can connect PS/2 keyboard and mouse, contains an IDE controller for hard disk and CD-ROM as well a Flash Card adapter.

Signals of PC keyboard are converted to standard Spectrum signals with some extras (for example F11: Magic Button, F12: reset). Signals of PS/2 mouse are converted to Kempston Mouse.

Anyway, the IDE controller is developed on the basis of Nemo's card. Empty circuit boards can be ordered for 300 rubles, and made in the Zelenograd factory such as the Pentagon 1024SL with today's standard. Those, who feel enough competent, with the free access documents can make one for themselves.

The developer was testing it on Pentagon 1024SL, Scorpion and certainly with KAY 1024 machines.

Pentagon 1024SL v2.666 already contains this extender integrated onto the mainboard, with some extras, such as USB and VGA ports, as well a real-time clock - as described earlier.

Z-controller v1.0

ZX Multi Card

ZX Multi Card v1

ZX Multi Card is the inventment of the Russian Caro (real name: Kamil Karimov). With help of that device, quite well can enhance the possibilities of the Spectrum.

Through the card, we can attach PS/2 keyboard and mouse, and it is also contains a real time clock.

Signals of PS/2 mouse are automatically converted to Kempston Mouse signals. In addition, this multifunction card also contains a modem. These devices can be tested trough built-in programs with pressing Win, F1, F2 and F3 simultaneously.

With further module enhancements SD/MMC cards as well conventional tapes can be used as storage devices. An another extender contains a MIDI Out port.

Version1.x boards were followed by the v2.x ones, which have bugfixed board. Beside that, some ICs are integrated into a simple circuit.

Again, all documents are freely available.

ZX Multi Card


ProfROM Second Edition

The initial disgusting feature of Scorpion from other clones was the utilities burnt into the ROM. The so-called ’Service Monitor’ first only occu

TBBlue Brazil

Fabio Belavenuto (FB Labs) és Victor Trucco (VTrucco) közös projektje a TBBlue klón. Az ULA sikeres visszafejtését követően vetődött fel az FGPA alapú fejlesztés. Ez jónéhány ZX klónt és perifériát jelent. A 48K-s és 128K-s Spectrum mellett a brazil TK90X, TK95; ZX Spectrum 128K+3e, ZX80, ZX81 és Jupiter Ace konfigurálható.

A DivMMC lett a háttértár, SD kártya és esxDOS támogatással. Ez maximum 8 gigás FAT32 partíciókat kezel. Innét kerül betöltésre a firware ROM és a programok .TAP formátumban.

A hang AY-3-8910 vagy YM2149 emuláció, sztereó jack-en keresztül. A MIC és EAR is külön csatlakozót kaptak.

Két darab joy port is megtalálható, Kempston, Sinclair és Cursor 2-ként konfigurálhatóak. A második portra PS/2 adapter segítségével egér vagy fényceruza is köthető.

A crackerek kedvenc eszköze, a Multiface is integrálásra került One, 128 vagy +3 verzióban működik, éppen az aktuális kiválasztott klóntól függően.

Szabványos PS/2 billentyűzet és VGA csatlakozó is megtalálható rajta. Támogatja az ULAPLus grafikus üzemmódot is.

Végül kétféle 'kiszerelésben' készült el. Fabio dobozba szerelhető változatot képzelt el. Ezzel szemben Victor lapja belepasszintható egy 48K-s Speccy avagy TK90X/95 eredeti házába is. Mindkettőhöz külön kell megvenni az FGPA kiegészítő kártyát (EP2C5T144 Mini). Elbőbbi 2015-ös, utóbbi 2016-ban látott napvilágot.

Hozzáadva: 2016. április

TBBlue by Fabio Belavenuto
pied 16K, but extending its functions, soon reached the 64K limit.

Further utilies (’Professional Extension’) wanted to be load externally from floppy disk, so programs would occupy a portion of RAM. But this would lead to compatibility issues.

That is the reason why Scorpion decided to construct Professional ROM (ProfROM, which is a mini ROM board in 128K and 256K versions. First one can hold 80K of programs, second is capable of 208K. A 512K variant is also exists, which divides the capacity into two 256K parts, we can select them by a switch.

ProfROM has some nice features: compatible with SMUC, able to configure mouse and joystick, fast formatting of floppies, as well contains screen editor and debugger.

ProfROM Second Edition is the design of Witchcraft Creative Group existing 128K or 256K versions. With a jumper not only to Scorpion, but can be connected to KAY and ZXM-Phoenix machines too.

Worth to note, that Velesoft already in 2007 designed his own version. It only exists on ’paper’ at the moment, not tested by even the author yet.

Added: 2010. January 23.

Proface AT

Proface AT PS/2 version

The weak point of Spectrum was the keyboard for a long time.

For solving this problem, quite wide range of devices were born. Still, you can buy interfaces with PC-keyboard connector. So, you don't have to afraid about the keyboard membranes, you can use the cheaper and better quality PC-keyboards.

Proface AT is existing in some versions. It has an internal and an external variant. Internal is suitable for people who want to build their Speccies into a PC-case. Of course, the internal is a bit cheaper too. Velesoft also engineered the PS/2 version.

Resets are going in the same way as on PCs: Ctrl+Alt+Del. Some floppy commands, such as Format, Cat are accessible through the function keys. Certainly, you can use the cursor keys and also the numeric pad. It has some another extra features, but most customers buy the interface only for connecting PC keyboards.

The external Proface also has a thoroughgoing edge connector. Good quality Speccy keyboard stickers are also come along with the interfaces. Sintech, RWAP Software and Kompakt Services are selling it.

IBM PC Keyboard and Mouse Contoller

IBM PC Keyboard and Mouse Controller

Of course, Scorpion company also offers the possibility of connecting PC-keyboards.

Their joint development with D. K. (a firm also located in Saint Petersburg) is an universal XT/AT keyboard and mouse controller. It is compatible not only with Scorpion, but with another ZX Spectrum clones too.

The PC keyboard controller has some smart features. It detects XT/AT keyboards automatically. Also supports both Latin and Cyrillic keyboard layouts.

Common functions of most popular word processors (as TasWord, The Last Word 2, ZX Word) accessible directly from function keys. The same can be said from IS-DOS commands. Pressing Pause button will hang on running the programs, Ctrl+Alt+Del will reset the computer.

The mouse controller is converting the datas of Microsoft Mouse to Kempston mouse, make handling easier of new Russian software. But it also emulates classic Kempston, Cursor and Sinclair joysticks - even with autofire function.

Magic Button can be activated by keypress too.

Worth to note, that not all mouses and keyboards are compatible with the card. For that reason, better to buy it as a complete set (controller, keyboard and mouse). Russians also studying marketing...

The card is sold by Perspective Group too.

SpecKey United States

The initially in Great Britain grown up, presently living in the USA JROK offers an another solution for replacing the folie membrane of ZX Spectrum. The interface called SpecKey, aka Yet Another ZX Spectrum AT Keyboard Interface (YAZSAKI) and was born in 2006. The author was only wanted to play with Manic Miner, and see what is the result...

The fairly Japanese sounding interface only consists of two elements: the Xilinx XC9572 programmable logical circuit and the Amtel AVR Attiny45 micro-controller.

Of course, it supports the combined keypresses, so delete and cursor keys are useable among others.

The sample of printed circuit board, as well the driver software are downloadable from the website.


ZX Spectrum USB Keyboard Conversion

ZX Spectrum USB Keyboard Conversion prototype

Lee and LanceR, two friends made an interface with ZX Spectrum USB Keyboard Conversion name.

So from that easy to guess, that it is an interface for attaching USB PC-keyboard for the Spectrum.

After solving the construction of the original folie-matrix, they modified an old 18f4550 card of LanceR. After it was worked fine, they replaced it with a more good-looking PCB.

Hozzáadva: 2011. October 22.

TOSI Joy Interface Czech Republic

TOSI Joy Interface is the development of the Czech Milan Spacek. With it, you can connect Kempston or analog joysticks to the ZX Spectrum machines. We can choose between the two modes with a jumper. In Kempston mode, supports three fire buttons, while the PC joy mode supports two.

It also received a reset button and of course, as a Czech development, DivIDE compatible.

TOSI Joy Interface

Covox and Soundrive Russia Czech Republic

Probably most of you remember to the "poor man's soundcard" of early '90s - that was Covox. Some "scientific" names of the device: Covox Speech Thing or sometimes Covox Plug.

This is a simple digital to analogue converter attached to the parallel port. The signal can be boosted with hi-fi equipments, so both digitised effects and music can produced in quite good quality. Covoxes have some different versions beginning from IC variants to resistor type ones.

Covoxes had stereo and quadro versions also. First one is consist of two mono Covoxes, second is integrating four Covoxes into a small board (name of this device was Quadrofonic DAC).

Ready-made Covoxes were also commercially available named to Disney Sound Source. With decreasing the price of soundcards, Covoxes became less and less important - at least in the PC-world.

Among 8 bit home micros, Covox is widespread still (for example Atari XL, Spectrum, but the excellent products of Russian industry, Elektronika BK and Vector were also enhanced with Covox.). This was supposedly facilitated by the fact, that the AY-8910/12 and YM2148F sound chips did not have Russian analogues. Mono versions are existing, as well stereos. And Pentagon Covoxes a little different from the Scorpion's devices.

Quadro Covoxes named Soundrive (one "d!"). Just as at the PCs, four D/A converters integrated to a small board. First version was engineered by Flash Inc. from Novisibirsk in 1995. It has some different versions as Soundrive Normal, Soundrive Baby and Soundrive Monster. Covox and Soundrive were rather popular among users,who wanted to produce digital effects from the ZX Spectrum.

Versions are also become numerous such as 1.01, 1.02, 1.05, 1.50 and 1.51. Of course, Soundrive is Covox and Stereo Covox compatible.

Version 1.02 has 9 chips and in the Russian circumstances contained quite expensive and hardly obtainable elements.

Version 1.05 is made from cheaper and more widespread parts and can be made Covox compatible by a switch. Number of chips were reduced to 5.

Version 1.51 selects automatically Covox mode, if the program does not support Soundrive. Its schematics published in Flash Times diskzine in 1997.

Oleg Staricenko (solegstar) was designed the SounDrive v1.52, aka the SounDrive TLC7528C in 2011, and according to the good new Russian traditions, news was first published about it on the zx.pk.ru forum. TLC7258C is a two-channel D/A converter, which means, that two of them is needed. The card is ZXBus compatible, Caro helped to realize this. It also includes an AY input connector for mixing. Was also built a prototype from it for PC Centronics connector. Theoretically, it works also with a four-channel TLC7225 DAC, but this has not been tested yet by the designer. It is compatible with v1.51 both on software and hardware side, as well as with the Profi clone.

Black_Cat was released at the end of 2012 its bugfixed version, the SounDrive v1.53, which, unlike its predecessor, is already compatible with the ZXM-Phoenix 03 and 04 revisions.

He was also developed the SounDrive v1.6, which was almost released paralelly with the development of solegstar in 2011. It is also includes the bugfixes for v1.51 and compatible with ZXBus v1.1 specifications and the ports of eZ80 processor.

After two years, he was came out with its successor, the Ultra Soundrive v1.666. In addition to the usual bugfixes, all four channels have a 6-bit volume control. Works well with General Sound as Covox, compatible with the Covox mode of Scorpion and the Stereo Covox mode of Profi.

Covox and Soundrive's quality is 8 bit. In case of Covox the CPU must divide the signals in time-sharing system to the only port (1x8 bit) or at Stereo Covoxes to two ports (2x8 bit). Soundrive signals can directly ported to each channels (4x8 bit).

Russian games and sound softwares are using the different Covoxes. Greatest disadvantage of the devices, that producing music is completely done by the central processor.

Maximum quality is 10 kHz (with optimisation 12 kHz), if samples and volumes stored in high memory area. If the standard, low memory contains the music, then 15 kHz (or 16 kHz) could be reached.

Special Soundrive music editors: Digital Studio, Extreme Tracker, Flash Tracker, Ultrasonic and SQ Tracker.

Although in much less quantity, but in the territory of ex-Czechoslovakian Republic, Covox and Soundrive were also popular. These were home-made products since the second half of 90's, official manufacturers or distributors did not existed.

Their common points, not connected directly to the machines, but through the UR-4 parallel port interface. Among others, Petr Simandl and Pavel Cejka also published their circuit diagrams on their websites.

Updated: 2015. May 16.

Soundrive Monster
Soundrive TLC7528C
3 channel DA converter for UR-4
3 channel DA converter for Didaktik Gama 192K
4 channel D/A converter sound card
for ZX Spectrum 128K+2A and UR-4

ABC/ACB/CAB sztereó


Stereo music is invented by the Czech Spec-chums, who soldered some condensers and resistors to the AY-chip and getting stereo music in this way. The tuning can be connected to Busy and Noro. Petr Simandl was also published such diagram. This method was also popular in the territory of ex-Soviet Union and in smaller extents in Poland and in Romania too.

Although seems easy to make this modification, the AY-chip is very heat-sensible. So very easy to burn out the chip with soldering. Better to ask a more practised friend to realise this enhancement. Anyway your Spectrum will not music in stereo - in fact it will not music at all... Some DIY-sites are strongly recommending, not to heat directly the AY-chip, but better to soldering a separate chip socket.

ABC, ACB and CAB stereo modes referring to the orders of channel sequence. The AY-chip (as well the YM of course) has 3 different mono channels (A, B and C). These three channels are separated, and the channels marked with the two winger letters are sounding from the left and right speakers with full loudness. Centre channel is sounds from each speakers with half loudness. ACB stereo is the tuning of the Czech/Slovakian areas. ABC and BAC stereo was widespread in the territory of ex-Soviet Union.

The stereo sound not very difficult to take out to a hi-fi system, so not necessary to hear it from TV. By the way, AY-chip is capable to play digitised sound, although originally it is an undocumented feature. It is very CPU intensive task, and quailty does not reach 5 bit. Newer Russian games are fulfilled with digitised effects.

Stereo music is also becoming standard on most demo-compos.

For the 48K Speccies later appared the AY-chip interfaces, which had uncountable variants during the years. It has to modify a bit the 48K software to work properly with these enhancements -in that case, if they were not made to compatible originally. As before 1995 were not widespread the 128K machines in the ex-Czechoslovakian Republic, many games had been converted to 48K. Of course, our Czech friends tried to write 48K+AY compatible games.

At present, Melodik interface sold by Kompakt Services is the only one such commercial interface. It contains a built-in mono loudspeaker, but certainly can connected to the hi-fi equipment through a stereo 3,5 jack in ACB stereo.

Jarek Adamski's Yamod.AYLPT and Sami Vehmaa's ZXAY cards will described fully later.

Not belonging strictly to the topic, but worth to mention, that for some ex-Soviet clones was attached the stereo-tuned AY-chip through the bus system very similarly to the PC soundcards. The best example is the already mentioned Contact CPS-128. At the early Pentagons, into the socket of Z80 processor have to plug a small circuit which contained both the Z80 and AY chips - as we could read before.


Zaxon AY-Magic

Zaxon's AY-Magic soundcard is the usual AY-interface for the ZX Spectrum. Fully compatible with the 128K Spectrum and beside its rubber-keyed mates and 48K+, also works fine with the clones. Theoretically, can be used with all variants of 128K, 128K+2 and 128K+3, but uses the same port, as the original chip, so it have not much sense (emulation of further described Turbo Sound will not work). Has a through connector and a jack socket.

According to the text in the PCB, Yerzmey also helped in its development.

Anyway, Zaxon also develops various interfaces for the C64 and Atari 8/16 bit machines.

Added: 2010. February 21.

Turbo Sound Russia Czech Republic Poland

For those, who thought, the possibilities are ended with stereo-tuning and playing digitised effects with the AY/YM chips - they simple aren't right. The ancestor of 6 channel Turbo Sound (with two AY/YM chips) was existed in the SAM Coupe computer, although this task was integrated into a single Philips SAA1099 chip. Some sources from late 80's mentioned about similar developments for the original ZX Spectrum. Russians call this enhancement to Turbo Sound, Turbo AY or simply TS. Sources are speaking about it as the original development of Himik ZxZ (Himik, Ilya Kudryavtsev), the member of Power of Sound group, and later more anothers were further developed it.

Sadly nor each method compatible with others, except Velesoft's card. Let's see them step by step!

So, the POS-turbo (from 1995) is the creation of the Power of Sound group. Previously they made the TR-DOS version 6.1x (more exactly they cracked it...), as it was written at the Beta-128 section. Their modification is also a second AY with different port. They developed different interfaces for the original Spectrum, Pentagon and Profi. The group was released Turbo Sound Editor, other programs do not support this enhancement.

Pseudo-turbo mode is using the default port and a second AY-chip. The two chips are controlled by some phase-step delay from the same port.

Quadro-turbo (or Quadro-AY and in Russian: Kvadrapristavka) is a typical Pentagon modification: just put a second AY beside the original with different addressing port. Because one AY can sound in stereo, with two can produce quadro sound. This extended version saw the light in 1997 by Rush and Amazing Software Making. Unfortunately no programs are supporting this.

Turbo Sound was also the name of NedoPC team's first implementation. It was only made in small quantities, but the circuit diagrams and documentations are freely available.

The card contains the two AY-chips, and through an IDE cable can be inserted into the original place of AY. Its creators: Victor Roscupko (Ronin) és Roman Valerevic Cunin (CHRV). In 2005 was came out.

Three revisions made. Revision A was the first experimental model, the card has no protective coating. Revision B contains the fixes of the previous and coating was made on it. The Revision C can easily be converted to quadro sound a well

The aforementioned Turbo Sound Editor and Pro Tracker supports it.

Its successor, the TurboSound FM (TFM, TSFM), which is fully compatible with the previous. In addition, it supports the FM synthesis of Sega Genesis.

Two YM2203 chips sits on it. They are compatible with the AY and in addition including 3-channels FM synthesizer. As in the case of ordinary TS, it can be connected to the original place of AY. The system is controlled by a CPLD and two DACs also can be found in it.

It is made in three versions too. Revision A is the 'trial' version, again without coating. Bug fixes were introduced in Revision B (in which a wiring error is still remains). Coating was still missed. The final, Revision C, has been awarded the mask protection and the possibility to lock the FM part as well. In addition, it also received a filter component, and can be controlled the AY and FM parts. This is of course induced a firmware update.

The responsibles of development Vadim Akimov (LVD), Vasily Klimov (JTN) and CHRV, the release date also 2005.

The Czech VeleSoft (Jiri Veleba) also made his own versions. First got the Turbo Sound Easy name, and it contains only one AY/YM chip (all other versions two), as the card uses the internal chip of the computer. Also built in a Philips SAA10999 chip for emulating SAM Coupe sounds. So alltogether 12 channels sound we got. It is fully compatible with NedoPC's devices, and also with SAM Coupe.

For this was made the Sound Mixer for Sound Mixer for Turbo Sound Easy. With this 'easily' can mix the channels of ABC/ACB stereo AY-chip and the similrarly stereo SAA chip with the sound of the beeper.

Also available as complete device as Turbo Sound Easy with mixer.

The standalone soundcard was realized later without the SAA as Turbo Sound Mini. Mini refers to it size in this case.

The ZXM-Soundcard is the development of the Russian Mick (Mikhail Tarasov). The card is capable to play six channel music with 2xYM2203 as well with a Philips SAA1099. The AY/YM part is TurboSound FM (TSFM) compatible, the SAA1099 is with the SAM Coupe. Of course, with special software all 12 channels are available.

The first revision (revision 01) is compatible with the Nemo-bused ZXM-Phoenix and KAY-256/1024, and made in 5 pieces batch in 2010.

The development of the second serie (revision 02) was begin in the summer of 2010. It was born, because the fans wanted to listen its music on real clones, not only on emulator. And it was ready for the summer of 2010 in 'slim' construction which was due to the SMD components. As the card was slim, and had ZX-bus, could use the owners of different clones. Two pieces was made from the second.

The revision was released in the end of 2011. It got three voltage stabilizer. One for the mixer and SAA, and two for the two YMs. So the overheating problem was eliminated. If we do not need the TSFM part, we can block it with a jumper. He was manufactured 10 pieces. The card was used the Amtel ATF1502 controller in the first three revisions.

In the spring of 2013 was raised the question, whenever made new release from the card. Some potential users already had TSFM, and they did not want to 'duplicate' it. After the surveys was born the Light version, which was contained only the SAA part. Worth to mention, that the card become Pentevo/ZX Evolution compatible and got new controlling ports for the SAA, which was made in 21 pieces. The controller CPLD become the Altera EPM7032STC44.

On the basis of this card was made the Soundrive compatible version christened to Middle. Was using the TLC7226CN D/A converter, and made total of two dozens batch.

The final form was the Extreme variant, which development was begin on early 2014. In this, the TSFM part was arrived back, while also kept the Soundrive. The EPM7032STC44 controller was replaced with a bigger capacity EPM7064STC. With this, the reference frequencies become changeable, so can play CPC and ST music also. The last version was made in 38 pieces batch, from which the bugfixed version is named to Extreme rev 01.

The possibilities of the card is demonstrated by three disks, E-Tunes 1, E-Tunes 2 and TS-Play. First shows the possibilities of the SAA, and the last is for the TSFM part (it is the work of AAA, alias Medicament, 3A-Soft, Aleksej Alekseenko and VNN_KCS).

All cards have Line In/Out and stereo jack. Since revision 03 also two RCAs integrated.

The Polish Zaxon, Piotr Bugaj, the member of Speccy.pl community in 2013 first came out with reproducing NedoPC's Turbo Sound FM card. He was tested them on Timex 2048 computers too, which were widespread in Poland. After the prototypes (FM Magic), numerous cards came out from his hands, in which the type of DACs are YM3014.

Turbo Sound FM got the Masakrator FM name.

As Masakrator FM De Luxe debut in the intellectual heritage of Turbo Sound Easy, and it is virtually the analogue of Mick's ZXM-Sound Card. This is including the SAA, however, not one, but two has YMs (a'la ZXM). Unfortunately, the SAA does not work on Timex machines.

As Pierdalator appeared the card containing only the SAA, so you can get six channels stereo and capable of play SAM Coupe music as well. It is the replica of ZXM-Sound Card Light.

Zaxon's stuff can be bought through the webshop of Sell My Retro.

On the newer demo compos there are separate Turbo Sound category (Chaos Constructions and Di'Halt).

Despite the facts, this enhancement is not so widespreaded, because you have to kill a Spectrum, Atari or Sega to get the necessary chip. And not so many programs supporting 6 channel music.

After all, varying the AY/AM chips' clock frequency can result in better sound quality (1,75MHz, 1,77MHz or 3,5MHz).

Now the first TS music "album" came out too - which is a 640K TR-DOS disk.

Good news for the developers: full documentation of Turbo Sound was released as a book from Alone Coder.

Updated: 2015. October

Turbo Sound Revision A
Turbo Sound Revision C
Turbo Sound FM Revision ?
Turbo Sound FM Revision C
Turbo Sound Easy
Turbo Sound Mini
FM Magic
Masakrator FM de Luxe

General Sound 128/512, NeoGS, ZXM-SoundCard Russia

Anyone can turn his Spectrum or Spectrum-clone into a nearly Amiga quality sound machine in seconds with the General Sound card (abbreviation: GS) - no matter it is a basic 48K or a more advanced 512K model.

This card is the development of X-Trade Group from 1997 (Saint Petersburg), but Scorpion and Nemo also engineered their own versions. It exist at least in two different versions. The first, the older one was attached with a ribbon cable to the mainboard, the newer is directly mounted by an edge connector.

Thank to the complexity of board, home made or cloned GS cards not found on the market. To tell the true, this is the most difficult ZX Spectrum peripheral of the classical Russian ZX Spectrum era.

Certainly, most software does not use the extra capacities of the sound card. But most of newer Russian games, updated version of old classics, music editors and players are supporting it, some of them even autodetecting when the card plugged in.

In the case of old classic games, crackers are dug out the music and effects from the Amiga version, and simply attached them to the Speccy version. The soundcard excellent for editing and play back of Amiga originated .MOD files.

The hearth of GS is a Z80A, B, C or H running at 12MHz, with massive 128 or 512K DRAM. Fairly ironical an extension card, which is more powerful, than the computer itself...

Theoretically, as a coprocessor, can calculate everything independently from the computer's CPU. Even can share its memory with the ZX Spectrum. But this possibility is nearly unused in softwares.

Producing music is completely the task of the card's Z80 CPU, so it doesn't need serious resources from Speccy. When resetting the computer, GS will work further more.

Scorpion was included two disks along with the soundcard fulfilled with games and music.

If you see the GS128 or GS512 sign at a program, it means the support of General Sound card with 128 or 512K RAM.

Sampling rate is 37,5 KHz and has 4 different channels. Some of the sound editors with GS support: RIFF Tracker and Excellent Tracker.

In 2007 the documentation and circuits of the card was public released, so the previously only commercial product was freely available for everyone to production.

So NedoPC Group was developed also the new version of General Sound card, which was introduced on June 2008 on DiHalt 2008 with NeoGS name. Fully compatible with the 512K General Sound card, and has some extended capabilities. In the development was participated LVD (Vadim Akim), CHRV (Chunin Roman), King of Evil (Zhabin Alexei) and JTN (Vasiliy Klimov).

Sales of first devices began at October 2008 and cost of ready-made board is 1.800 rubles, the DIY-kit is 1.500 rubles. At the current moment, have two revisions: Revision A, which never went to sale, and Revision B, the final version with error fixes.

And now the technical details: hearth of the board is a Z84 running either at 10, 12, 20 or 24MHz selectable, has 2 megabytes of RAM and 512K (Flash)ROM. Capable of playing .MP3 and 8 channel .MOD files, even from SD card. Built-in DMA circuit accelerates the data exchange. From the SD card, can play the files independently from the Spectrum, what means, powering off the computer does not influences NeoGS.

Mikhail Tarasov also was created a soundcard, ZXM-GeneralSound. The idea of realizing of the card was appeared on the end of 2013. Its main reason can be said, that Mick wanted to realize a less 'powerful' card than NeoGS. On the other hand, he was found some TLC7528CDW DAC ciruits. So the project was finally realized in 2014.

The processor 18 (firmware v1.00, 1.01) or 12MHz (v2.01) running Z84C0020VEC. The RAM size can be from 512K to 2 megabytes with SRAM. The size of ROM was also increased to 128K, from which the original ROM was placed into the low 32K. The controlling circuit is an Altera EPM7128STC100 CPLD. Stereo output was realized with a 3,5 jack and two RCAs.

In the designing of the hardware was gave help Sergey Sirotenko (Blade) as well Black_Cat.

General Sound new version
General Sound memory module
NeoGS prototype
NeoGS revision C

SID-Blaster/ZX Russia

The SID-Blaster/ZX soundcard is basically a C-64, from which the keyboard and video controller was catted down, and which connects though the Nemo-bus to the Spectrum (clone).

The aim of the development starting from 2011 autumn was to create a soundcard capable of playing SID tunes on the ZX Spectrum.

Developers: Byteman (Alexander Alexandrow) and Prusak (Sergey Bagan) First one is created the basic conception, and made the firmware coding of Motorola 6510. Prusak's area was the hardware development, soldering, debugging and ZX Spectrum software development.

The card is simulating both PAL and NTSC systems, SID 6581 and 8580 soundchips also built-in for better compatibility.

The conception is similar to General Sound card, because this also has its own CPU and BIOS.

Added: 2012. March

SID-Blaster/ZX prototype 03

DMA Ultra Sound Card Russia
DMA Ultra Sound Card (DMA USC) developed by Witch Craft Creative Group commonly with Aleksei Inozemtsevym in 1999. This Ukrainish novelty is a non-profit inventment, which never planned to push into serial production.

Its schematics are freely available. Thanks to the complexity of card (40 chips), difficulties in attaching to clones, as well to few programs using the possibilities of the it, it does not widespreaded too much. Nevertheless, it becomes fairly well-known due various publications of press and electronic magazines (MSD, Echo, Adventurer and Body). Unlike the more popular General Sound card, it does not have own memory, but using the computer's memory with direct memory access. With that method, opposite of Soundrive, CPU usage is only 15% when playing four-channel music. So theoretically 85 % left for games to run.

Attaching DMA USC card to clones needs high level skills. There are many different ZX Spectrum variants, that is why impossible to connect it without special knowledge. The user's guide deeply explains how to use the card with Pentagon 512K and KAY 1024K clones. From this seems, that recommended the card to attach for machines with minimum 512K memory. Another problem is, in turbo mode the card is unreliable. This could be solved only with a hardly available chip.

Developers of DMA USC adopted a number of music editors for this device. Some examples: Access Player, X-Tracker, Digital Studio, ProDigital Editor.


DMA Ultra Sound Card

Miki RS232

Miki RS232 interface bottom view

Miki RS232 interface initially was the inventment of Busysoft. This one is connected through the UR4 interface, and offers standard RS-232C input/output. So it is basically a serial-parallel, parallel-serial converter interface. It is also possible to change data between the ZX and PCs. This circuit was realised with the AT89C2051 chip.

His compatriot, Cygnus also fabricated his own version, which is built around the AT Mega 16 chip. By his oppinion, its reason is more easy programming under Linux.

From the homepages, detailed informations as well some utilies are also available.

Sinclair Serial Interface Czech Republic

The Sinclair Serial Interface (Sinclair SIF) is the development of the Czech Pavel Urbancik. It has three main subversions, the newer ones offering backward compatibility with the oldies. Additionally, new functions were implemented and also got some error corrections comparing to older ones.

The hardware itself a dual channel serial interface, ready to open the door to the ‘real world’. First channel is an usual cabled RS-232C connection, ideal for example to connecting PCs. The another channel is an option to integrate a Wi-Fi or Ethernet component.

The possibilities are practically endless, ftp, text-based www or e-mail clients etc., but almost no software developed.

For 1.000 CSK or 40 Euros can be ordered without the Wi-Fi or Ethernet module.

Updated: 2016. March

Sinclair SIF prototype

Pokeador Automatico

Pokeador Automatico interface top view

Fernando Fdez was published in 2005 the documents, which are necessary to rebuild the Pokeador Automatico interface as well the utilies, which are working with this hardware.

This one is a Spanish inventment, with which you can enter POKEs in the games as cheatings - presumably as the name suggests.

Reconstruction was prohibited by the fact, that documents were released in three different issues (Microhobby 117-118-119).

On the homepage, we can found the relevant three issues, the printed circuit board (which was redesigned by Fernando a bit) and the utilies. Original parts are also listed, and some recommendations to replace them with more common and cheap items.

SpeccyBoot Sweden

Patrick Persson successfully solved the booting of ZX Spectrum over on Ethernet network. The pack, which consist of hardware and software parts (both for the network PC and Spectrum) got the SpeccyBoot name.

This method was originally designed for diskless workstations for booting over a local network. SpeccyBoot is works in a similar way.

The machine gets an IP address over DHCP or BOOTP, then starts a file from the TFTP server (snapshots.lst), which is the list of the snapshots. Then from this list we can choose the right snapshot, we would like to run.

In case of Spectrum, pressing Caps Shift during the 'boot' loads the normal BASIC if the SpeccyBoot is connected. Or this can be equally achieved when closing jumper 1, which disables the EEPROM.

The card is made with the MicroChip ENC28J60 Ethernet Controller. The author used the Olimex ENC28J60 -H development board, which is contains the previous chip. The price of SpeccyBoot is around 20 Euros with some another additional accessories in this case. If we do not use the whole development board, only the chip with its accessories, the final price is cut down to 10 Euros.

After building the hardware, needs to install the software. After compiling the source code, we get a .WAV file, which is need to load into the Spectrum (for example from a mobile phone). Then this program needs to burnt into the EEPROM. Of course, we have to open the previously mentioned jumper.

The card is compatible with 48K/128K/128K+2 machines (maybe also with the 16K ones). Later Amstrad models have different layout edge connector, so without modification will not work (of course, this modification is possible, but Patrick did not have the opportunity to do this). Maybe using Velesoft's ZX Bus protector and +2A/+2B/+3 fixer?

Ik0n was made the version for Didaktik Gama named DGBoot, from which we can read about in the Sindik.at section.

Updated: 2016. March

Olimex ENC28J60-H



With Graphics Memory eXpander card easily "downgradeable" a Scorpion into a Pentagon. Any reasons for that? Well, yes, because the new age games and demos are mostly made for Pentagons, and they don't work properly on Scorps. GMX is soon became the favourite card of demoparties. It's because of faithful Pentagon emulation and it is more reliable and stable like the usually home-made Pentagons.

It emulates 4 another Speccy-variants, including Profi, from which inherited the memory mapping techniques between the 256K and 1M range (backward compatibility). Scorpion says, its reason is, that Profi 1024 is a relatively widespread clone with good software support – especially with end user applications. If we switch off every extra, we get back to the original Spectrum, except of the rubbers keys.

GMX gets some innovative features also. It has 2MByte of RAM, where can be loaded a lot of different things - for example ROMs in order to speed up your Scorp a bit. The card's CPU is a 3,5/7MHz Z80B, can be useful when playing Driller:) The 14MHz version was promised for years, but for now it is sure, nothing will happend with it. Difference between normal and turbo mode approximately is 1,8-1,9x; but with shadowing it is exactly will 2x faster. Some other possibilities of the card are including new graphics modes (for example 640x200) with standard Speccy colours. Also Multicolor capable. The new text mode offers 80x25 characters and can be displayed either on TV, CGA, EGA or VGA monitors.

The biggest problem with the GMX its price. It is equivalent with a complete Scorpion config - so an average user can only dreaming about it.

Kempston Mouse Great Britain Russia Czech Republic Slovakia Netherlands Poland

Kempston Mouse was originally the product of Kempston Micro Electronics Ltd. in 1986. It came along with a special version of Art Studio. As probably everybody knows, the company was famous from its joystick interfaces.

Comparing with its main rival, the AMX Mouse, works fine with 128K Spectrums also, maybe because of it becomes the standard equipment of ex-Soviet clones. In Europe never reached wide popularity, despite the fact, was more superior quality than its rival with the same price, around 70 pounds. Although it went quite popular in the ex-Czechslovakian Republic beside the ex-Soviet Union.

Russian version was developed independently by two different Spectrum owners nearly at the same time in Saint Petersburg: Maxim Romanov (RML/Create Soft) and Mikhail Kondratiev (MI&DI). Description of first version released in the issue of ZX Format magazine in 1996 December, and the second variant published in the same year's in October in Spectrofon. The Russian Spectrum newsgroup, fido.real.speccy released to public the parameters of scrolling mouse by his e-conference in November 2001. Meantime was appeared the three and four buttons versions. Great advantage of Russian versions using very few CPU resources.

Czech and Slovakian Kempston Mouse was the development of Kompakt Services from 1994, and Proxima also sold an UR-4 version. In 1999 Hinek Gajda (HG Elektro) released the second version, it was connected directly to the Kempston joystick port. From these seems its basic disadvantage: it is not a real mouse, but rather a joystick compatible solution with the possibility of slowing down the cursor. Anyway, from it also derived its main advantage: works fine with most programmes, as Kempston Joystick is widely supported.

Velesoft also made his own versions primarily on the basis of the Russian ones. First version appeared as DIY-kits, and supported only one button. Newer, green colour printed circuit board, named to Kempston Mouse Turbo 2006 has USB and PS/2 ports, and uses the second and third buttons also (its 2004 version seems a short lived one with old firmware). Hard to believe, but we can attach two mouses to the Spectrum (with master/slave selection). Also has a video composite output. If it is even not enough, beside the external interface, they developed an internal variant too. It can speed up to 4x the controlling, which can be useful with older, classic arcades.

Kempston Mouse Turbo 2008 is made with new, improved and bugfixed board with Kempston and Fuller joystick support.

Kempston Mouse Turbo 2011 also supports Sinclair joy, as well emulates the keyboard. Now can be connected together two interfaces, again in slave and master mode. Manufacturing and configuring of the interface also became simpler. This version was made by the Dutch Ben Versteeg, who produced and sold earlier K-Mouses. The v2006 and the v2008 upgradable v2006 is made and sold solely by him with user manual and a scroller mouse. The v2011 could be ordered through the webshop of RWAP Software (SellMyRetro).

It low-profile version is the K-Mouse Turbo 2017-LP

Most of Russian end user software and some games are supporting Kempston Mouse as standard, and Velesoft converted numerous old programs also.

Jarek Adamski also developed Kempston Mouse compatible interfaces with Yamod.ZXINPUT and Yamod.KMOUSE names. We can read about them right now.

Updated: 2017. December

Original Kempston Mouse
Kempston Mouse Turbo 2005 external prototype
Kempston Mouse Turbo 2006 external
Kempston Mouse Turbo 2006 internal
Kempston Mouse Turbo 2008 external

Spectrum Logic Array Module Great Britain

Mark Smith's SLAM project (Spectrum Logic Array Module) is aimed to replace the ULA with using the Xilinx XC95288XL CPLD.

Altogether four versions are planned. SLAM48 and SLAM128 are the standard 48K and 128K versions, SLAM+48 and SLAM+128 are compatible with ULA+. So far, SLAM128 almost finished.

Anyway, all models are compatible with the original ULA according to the tests. Hopefully, as soon as they are completed, it may give a further impetus to the development of modern clones.

Hozzáadva: 2015. December


ZXKit1 VGA&PAL board


ZX1Kit VGA and PAL board by zst from zx.pk.ru

Development of zst, the ZXKit1 VGA&PAL board is a device for Spectrum and its clones with the purpose to lead out the picture to VGA monitor or TV-set (through S-Video, and RGB composite).

By default, it is compatible with Leningrad, Scorpion, Speccy 2007, Pentagon 48/128, ZXM-Phoenix, ZX-Next and Robik clones. With firmware update, also works with Profi, Orion and Specialist machines.

It has two modes, selection is done by jumpers. First mode is centering the 256x192 Speccy screen on the standart 640x480 VGA (rest of the picture is Border). Second one is ‘upscaling’ the ZX picture to the VGA screen.

Can be ordered as empty PCB, PCB+parts, finished board with standalone VGA or VGA, S-Video and composite output.

Added: 2010. February 26.

Scart RGB to YUV Component Video Converter

United States

Scart RGB to YUV Component Video Converter (from vintagecpu blog

Vitagecpu, who is living in the USA, describes a very interesting viewpoint for the Europeans. As on their TV-sets no Scart input (in full name: Euro-Scart), so standard RGB-Scart cables are useless. It needed a separate Scart-composite adapter also. In case of Amstrad CPC464 it gives black and white picture, while with ZX Spectrum 128K+2 it does not work at all.

The RGB-composite cable works, but the picture quality is far from the perfect (but still more superior than the picture of the RF modulator.)

So vintagecpu bought a Scart RGB-YUV Component Video converter. The 'case studies' on Internet describing half-successful stories. It sometimes works, sometimes not. Maybe you will get colours, maybe not. One of the two tried televisions (NTSC/Pal/Secam multi system) it worked perfectly with razor sharp picture. So we can definitely pick it up among the 'suggested' ZX Spectrum peripherals.

Added: 2011. April 02.

Antonio Villena's expansions Spain

Kartusho V4 is Interface 2 compatible cartridge unit, which includes 512K FlashROM. So, the board which made by the Spanish Antonio Villena can store 32 pieces of 16K and 10 of 48K ones.

The unit is supplied as a kit: with PCB and component combination. Was saw the light at the beginning of 2016 with the price around 10 Euros.

Interface ROM (ifrom) is its further development, but this one is not a ROM cartridge, but a interface connected to the edge connector. Should be noted, that compatible with all variants of 128K machines, you need to set this mode by jumper. Price similar to previous one.

Updated: 2017. February

Kartusho V4
Interface ROM

Jarek Adamski's expansions Poland

The already more times mentioned Polish Jarek Adamski, also offers numerous (or more exactly countless) novelties for the ZX Spectrum. Most of them realized meantime of the Spectrum SE development.

The ↑DiwIDE interface↑ was developed jointly with Jurek Dudek from DivIDE.

The Yabus.ZX is an interface converter, to which connected into the edge connector of ZX Spectrum, gives the possibility to attach the Yabus devices designed by Jarek into the dual slot.

The prototype of this device was the Yabus.ZXMEM. This would offer three thoroughgoing edge connects and the same quantity of Yabus ports. All above, 32K EPROM and 32K SRAM would built into it. So, we could choose from boot-menu between the different devices (for example MB-02+, +D etc.). The Yabus.ZX due its design, it is much more safe like the Sinclair edge connector, and we do not have to care about the joining sequence. The compatible peripherals gave the Yamod. family name, so we will get know about them.

The Yamod.AYLPT is an AY-3-8910 interface made in two different versions: the basic Med only contains a serial and parallel port above the AY-chip, the more advanced Max got real time clock and has own EPROM also.

The card can work in ZX128 and Timex 2068 compatible modes, even in the mixture of the two. We can attach two cards to the computer in the same time, so one can work in Sinclair, another in Timex mode saving the valuable time of jumpering. In the same way, we can select ABC or ACB stereo with jumper. Thanks to the integrated slot, various peripherals can be attached to it: TC2068 joystick, Keypad or AY-mouse.

The card is useable in a reversed way through the parallel port: we can control the AY-chip with a PC. Some emulators are supporting this method, giving more vivid AY-emulation. In the Spectrum slang, these cards are called LPT-AY interface.

Yamod.ZXINPUT is giving possibility to attach PC keyboard and mouse. Mouse signals converted to Kempston Mouse. Keyboard layout stored in EPROM, so easy to modificate it. Macros also can recorded, and RS-232C port can used for serial communication too. Beside ZX, can used with SAM, Byte, and Elwro.

Yamod.ATBUS is an universal 8 bit IDE interface. Its purpose of using hard disks, CD-ROMs, Zip drives and CF cards with the Spectrum.

Transfer speed is above 200KB/sec. With some tunings can simulate the MB-02+, Interface 1-bis, ZXATASP and Divide interfaces as well Pera Putnik's creatures.

Beside the IDE controller, the board may contain a real time clock also. ZX, Timex, Sam and CPC compatible.

Yabus.IDE8255 realised by the 8255 chip and its aim to control IDE devices. Above the mentioned chip, only one logical circuit needed for building one. The internal 8255 chip of MB-02+ also useable with a special cable. Due to simplicity it is relative slow. The author engineered a CPC version too.

The ZX512 named memory upgrade was made in one and only prototype and designed for the 48K Spectrums and TC2048. This one can expand the memory to 256K or 512K, as well providing ZX128 and Pentagon 512 compatibility. Jarek was also engineered a Multicolor circuit for this device. Going forward in this artcile, will see, that Velesoft already finalized a similar card.

ZX4MB is the succesor of the previous. Only on Issue 6A board was tested. Thanks to the 4 megabytes expansion, this one is also compatible with ZX128 and Pentagon 512. Due to the size of memory, quite complex operating systems would fit into. Also Multicolor compatible. Optionally can used with the FlashD0 extender, which is a 128K PEROM card.

PL3MEM is a memory expander and an IDE interface on the same board. Memory consist of 32K RAM and 64 or 128K EPROM, which basically occupied by the operating system. The IDE interface is the already known Yamod.IDE8255 type. As the name points, it can simulate the work of +3(e) on 48K/128K/128K+2 and TC2048/2068 machines. It is possible to insert a 512K EPROM card into the place of original EPROM, so numerous alternative ROMs can be chosen. The Yamod.IDE8255 can also replaced with Pera Putnik's simple interface.

ZX bus splitter divides the edge connector into three. Some different subversions were engineered. The v004 offers some another sweets: DIP switches for selecting the active ports, reset and NMI buttons, serial port for Kempston joystick, and LEDs giving operational feedback.

With the Yabus.ZXISA card ISA cards can connected to the Speccy. So cheap serial and parallel ports as well floppy controllers can be obtained in this way. Through the HDD controller also we can connect joystick.

Another expanders which worth to mention: Yamod.EPROG is and EPROM burner, but practically useable as parallel interface. A Yamod.KMOUSE and Yamod.KMJOY are Kempston Mouse and Joystick interfaces. A Yamod.EPLIP is a fast parallel interface. A Yamod.PCMOUSE is a simple serial mouse card. A Yamod.SIO was made for radio amateurs: turns TNC modem the Spectrum. Finally, Yamod.ETHERNET a bit expensive Ethernet card.

All cards are can be ordered as DIY kits or ready made.

Updated: 2020. August

Jarek Adamski


DiwIDE by J. Adamski and J. Dudek
DiwIDE v212
DiwIDE v317 red

Miguel Angel Rodriguez Jodar's expansions Spain

The Spanish Miguel Angel Rodriguez Jodar also belongs to the growing mass of active developers

In 2006 developed the Internal PS/2 keyboard adapter for ZX Spectrum+. This is compatible with PS/2 keyboards and also with USB ones with adapter.

His original goal was to reconstruct the 48K+'s damaged keyboard membrane. It seemed to be very difficult, so finally he decided to build the adapter. With this we can record and playback macros, cursor keys are useable as Sinclair joystick and with Ctrl+Alt+Del combination can reset the Spectrum. The PBC can mounted into the empty place near the loudspeaker. The adapter was made a bunch of quantity for some friends. At present, Ben Versteeg is push it into small quantity production. This one is an external, horizontal interface, so fits well to any Spectrums.

For replacing the damaged memory modules was authored the SIMM adapter for lower 16K RAM replacement. Primarily was designed for fitting instead of the usually defected low 16K, but also useable for the upper 32K memory area, and to restoring both 64K banks of the 128K machine. The idea based on a similar MSX project. Using this serice tip was made Alwin Henseler his own version with SRAM chips.

The forthcoming project is still under development. This one is an ultra fast loader, with the purpose of speed up the loading speed from SD cards, CDs etc. Was successfully tested with Flash memory and achieved 180Kb/sec. The idea is based on Codemaster's game compilation CD, which was loaded games within 20-40 seconds.

The next development is already in prototype stage. This is a TMS9929-based MSX compatible video controller board. Its exact name is: MSX Video for ZX Spectrum.

The TMS chip itself is a video controller for general purposes, which is also used in ColecoVision and TI/99 beside the MSXs.

Which advantages can obtained with such a card? We can highly superior the characteristics of the original ULA, as it can control his own 16K video Ram, and the video controller does not uses the resources of the processor. It communicates thought two ports with the CPU, so acts like an external peripheral.

The new graphics modes are the followings: Text: 40x24, monochrome; Screen1: 32x24 chars, 256x192 pixels with sprite support; Screen2: 32x24 chars, 256x192 pixels with 8x1 attributes again with sprite support - this mode is best for quality games; Multicolor: 64x48 big pixels, although each pixels can be different colours.

The card contains the video chip, some DRAMs, a GAL 20V8 circuit. The purpose of GAL to reduce the necessary amount of other circuits, as well is easy to reprogram.

There are some examples about rewriting some MSX programmes of which source codes was given by the Spanish MSX community to the developer.

The card is compatible with all Spectrums.

In 128K and later Spectrums, the Philips TEA 2000 is responsible for RGB to PAL encoding signals from the ULA. This one is very sensitive for electrostatic, and also easily overheating.

After repairing a 128K+2A (Issue 4) all problems were solved, except one. The composite TV-out signal remains black and white. As the TEA is quite rare one, so the idea was raised to replace it with a modern equivalent.

This chip works with 2bits/color data digital signal, one is for the color, second is the 'bright' attribute. So altogether works with 6 bits of digital data. The Analog Devices AD722 – as the most modern RGB-PAL encoders- works with analog RGB signals. So the replacement circuit must simulate this 2x3 bits data stream.

Two prototypes were made from the TEA 2000 replacement daughterboard. In the first, the crystal gives 4,43 MHz by default. In the another, the 74HCT74 IC transforms the 8,8MHz of TEA for 4,43, which is necessary to drive the AD722. All of two PCBs are single sided, and not containing the audio out.

By the way, the developer also publishes in the Zonadepruebas Spanish community site with McLeod_ideafix name.

One of his publications is the +2A/+2B/+3 downgrade to 128K+2. This one is explored, when searched the error in a dead +3. He was though, that the ULA went wrong, meanwhile explored the incompatibility reason of the Sinclair and Amstrad generations. 128K+2 has two pieces of 16K ROMs (ROM0: 48K, ROM1: 128K). In the case of the value of the actual port is 0, then 48K, when it is 1, the 128K ROM loaded in.

Later machines had 2 pieces of 32K ROMs (for +3DOS and CP/M). So Amstrad introduced a new port, the 1FFD for addressing these. Fixing this issue to replace the first 32K ROM with the original 2x16K ones. And it is works flawlessly! The only disadvantage of this method, that +3DOS and CP/M will not work. But solving this, it is an another story.

McLeod also solved the always warming ULA problem. It got a heatsink of a good old 286.

Next tip is the Composite video output for 128K. This one is basically a modification of the 8 pin DIN connector of the 128K Spectrum, which originally was worked as RGB. First step is to direct the unused pin 1 to the mono audio signal. Next one is to convert the black and white signal to colour. For do this, must be solder out the first leg of D34 diode (or cut it - it is more comfortable). Now it is time to detach the audio signal from the video. The C126 condenser must be deactivated, which is mixing the audio and video signals for the TV arieal output. Some soldering, and the cable is ready! Quite interesting, that this cable is fully usable for Dragon 32/64 computers without any modifications.

At last, we can found methods for using VGA monitors also.

First possibility is an approximately 30 Euros Noname RGB-VGA converter from China. This is basically an "industrial" one, we set it once, and ready for use. The disadvantage, is that if we have more retro machines, quite difficult to use. When connecting to the ZX Spectrum 128K +3, it uses the VGA picture after mixing the two half pictures in interlaced mode (we got great areas when mixing black and white.) Refreshing is not so perfect, as frequency of TVs is 50MHz, VGA's is 60MHz or more. But using it with QL, gives a perfect picture.

The another product, which he was tried out, is the DealExtreme converter. This has composite video and S-Video input also. First one is usable for 128K Spectrums, for the second, needs some modifications. The converter has a lot of functions, and can handle the PC and retro picture in PiP system on a VGA monitor.

And all above that, participiated in the development of an FGPA-based clone, named ZX-Uno.

On the OpenCores hobby electronic portal have also a publication, the ULA chip for ZX Spectrum (codename: zx_ula) . It is available in two subvariants. First is an FGPA, second is CPLD version. First has separate I/O bus, so can be a base of different clones. Another one is a "plug and play" ULA replacement, Which can be built into a working clone (such as the Harlequin). Beside, it is successfully simulates the original ULA, also support the Timex HiColor and ULA+ modes. This was integrated into the ZX Spectrum on pipistrello card also.

Upadeted: 2016. March

Internal PS/2 keyboard adapter for ZXS+
SIMM adapter for lower 16K RAM replacement
MSX Video for ZX Spectrum
TEA 2000 replacement daughterboard

Dr. Beep's expansions

ZXPC interface

Ymond Reconstruction Service (YRS) is a Dutch team was founded in the classical times of ZX Spectrum. At the moment, has only one active member, Dr. Beep, alias Johan Koelman.

Dr. Beep's ZXPC interface is connecting the ZX Spectrum with PC through a parallel port. The interface realised with combining two cards: a simple I/O card and an EPROM circuit. With this, . Z80, .SNA. .SCR and .TAP files stored on the PC can be loaded into the Spectrum. In the near future, supporting of .MDR (Microdrive) files is also planned. 48K programmes are loading within 7 seconds.

Dr. Beep is also developing a hardware ZX81 emulator for the ZX Spectrum. This one is realised by a selectable 32K ROM combining both machines' ROM routines.

Sami Vehmaa's expansions

ZXMatrix interface

The Swedish Spectrumist, Sami Vehmaa's developments are quite interesting, as he making continuously the various interfaces, which can expand the possibilities of ZX Spectrum in very different ways.

With the ZXCF, ZXCF+ interfaces, we can use Compact Flash cards as storage devices for the ZX Spectrum. The ancestor was already born in 2003, plus version is the fruit of 2007 year and the +2 upgrade, which is connectable to ZXCF+ was made in 2008.

They driven by the ROMs containing ResiDOS, which we got know about the ZX Spectrum +3e. The card is supports both load and save commands.

His most crispy development is ZXMatrix, which combines ZXCF+2 and ZXUSB cards. Between the two modes we can select with jumper or switch. Main features: 1 megabytes of RAM, USB 2.0 support and high speed CF reading-writing. Vehmaa also made his own version in only one piece. It has 2 megs of RAM and built-in Kempston joystick port.

ZXATASP interface is an earlier development of the author. This is a 16-bit IDE interface with hard disk and Compact Flash card support. The memory can be 128 or 512K. ResiDOS also supporting this device. ResiDOS could be loaded into this memory, so not necessary to rebuild the Spectrum. As the winchester needs an external power supply and the same time of falling down of the prices of CF cards, this card becomes less important.

He was also engineered his own ZXAY interface. It contains the AY-3-8912 chip and suits for 16/48K Spectrums. In the classic era lots of manufacturers and amateurs made similar sound enhancements. This one is sounds in ABC stereo.

The ZXMEM interface is expanding from 512K to the nearly unbelievable 32Mbytes the memory of 16/48K Spectrums.

Vehmma also made a real time clock (with date and time) and a high-speed serial port too.

ZXEXP adapter is an expanding tool, which thorough ZXBUS (the own inventment of the author) could offer the possibility of attaching more interfaces at the same time. All of the author's cards are equipped with ZXBUS. And the last four units only have this expansion system. This ZXBUS of course not the same, as the Russian Nemo-developed standard.

His laptop will be described in a separate section.

Jiri Veleba's (Velesoft, George Velesoft) expansions Czech Republic

Russians were reverse engineered the wiring diagram of the European ZX Spectrums and peripherals and then make them from Russian parts with adding their own ideas to them . The Czech Jiri Veleba (Velesoft, George Velesoft) reverse engineered these innovations backwards, and built these Russian innovations from European parts. He is not only developing for ZX Spectrum, but also for Sam and Timex Sinclair.

The Kempston Mouse (Turbo), Turbo Sound Easy, Sound Mixer for Turbo Sound Easy, Turbo Sound Easy with mixer, Turbo Sound Mini and the PS/2 Proface AT have already been described in detail.

At the ↑MB-02+↑ section, the Data Gear and MB-02 memory interfaces also have been discussed before.

We have also talk out his ↑DivIDE-related enhancements↑: the DivIDE 512, the DivIDE 57d series, and the Joystick and RTC module for DivIDE accessories for the latter.

The Pentagon 512 interface is an internal card for ZX Spectrum 128K+2 (only compatible with Issue 3). The timings of Pentagons are different from the ZX128, in addition, all memory banks and ports are handled as fast ones (Fast IO mode). So programs made specially for Pentagons, are more or less incompatible with the original Spectrums. The interface also solve this problem beside the memory expansion, which is realized with one piece 512K SRAM module. Thanks due to the Pentagon mode, original ZX Spectrum programs are also running faster, which is handful for compressors, image editors etc,

It also contains a 128-512K FlashROM, in which we can store alternative operating systems. This upgrade also supports the Unrain function, and co-operates with the D40/D80 systems. Some of the utility, such as MDOS File Commander and 128Tools using the full memory, so do not have to care too much with changing the discs.

The External 128-512K upgrade for ZX16/48K is similar to the previous, but this one is an external interface made for the 16/48K little brother. In the case of 48K machine, the higher 32K must be removed. The card works with 128 and 512K SRAM modules. When 512K one used, the machine will be compatible with Pentagon 512K and also will be faster than a ZX128. Of course, it is possible to switch off all extras and go back to the ordinary 48K mode. Unfortunately, the expander do not supports the shadow videoRAM, but using of the extra ROMs are possible.

The successor of Pentagon 512 interface is the ZX Profi interface, which gave its name from the similarly named Russian clone. It works only with the Issue 3 grey 128K+2 Spectrum, and its roots going back to 2004. Velesoft refreshed the old project, and fully redesigned the interface.

1 megabytes of RAM, 512K FlashEPROM, a Z80 processor and a battery take place on the single circuit board. ZX Profi 1024, Pentagon 128-1024 and Scorpion ZS 256-1024 compatible. DivIDE, MB-02+, ATM Turbo and Russian cache emulation is under construction.

A ZX 128K ULA clone is also under development. Seems, will be soon built the next Czech superclone...

Hyperface is a new type interface. Contains three ports with direct access, as well one conventional one. Velesoft into his own interface packed a divIDE and Kempston Mouse Turbo interfaces.

In 2007, also designed his own ProfROM clone. It only exists on ’paper’, and did not tested even by the author.

A tiny, but really useful thing is the ZX Bus protector and +2A/+2B/+3 fixer mini card. This can be connected to the Sinclair edge connector. It has double purpose: avoid the data collusion, as well to use the non-standard pinouted 128K+2A/+2B/+3 machines with the old peripherals.

Can be used in multiple configurations. When using the old peripherals with 128K+2A/+2B/+3 machines, must be deactivated the R2 resistor (in this mode compatible with 128K/+2 also). It converts the ROMCS pin of the peripheral into ROM1 OE/ROM2 OE.

If the only purpose to stabilizing the data transfer in the case of 16K/48K/128K/+2 machines, the R2 resistor, D1 and D2 diodes must be eliminated.

Next config is switch off the extended memory and ROM1/2 OE and ROMCS lines, and it is handles the peripherals as a direct port. R1, R14, R15, R16, D1 and D2 ports must removed. It is compatible with all Spectrums. Cand be handy, when using 128K+3e machines with DivIDE interfaces.

Version 2 is the same, but the PCB got better design to attach the peripherals more easily (in case of 128K+2A/+2B and +3 there is small room between the power socket and edge connector).

Version 5 got a jumper in order to get +12V on the +9V port of 128K+2A/+2B és +3 (on the previous version +9V unused).

Updated: 2020. August

Jiri Veleba


MB-02 add-ons
Data Gear 2007
MB-02 memory

DivIDE interfaces and add-ons
DivIDE 512
(2008. 07.)
DivIDE 57d2
(2012. 03.)
Joystick module for DivIDE 57x
(2012. 05.)
RTC module for DivIDE 57x
(2014. 05.)

Jiiira's expansions Czech Republic

We have already become acquainted With Jiiira's activity connecting to the Sparrow 48K motherboard.

The ZX ExpBoard is a "splitter" card cab be connected to the edge connector of ZX Spectrum, allowing multiple peripherals to be attached simultaneously (ZX ExpBoard 2 and ZX ExpBoard 3). It includes a through-going edge connector too. The design of 2011 PCB makes possible to make both the pin and the edge connector version.

He was also designed some "simple" accessories, which are including the Simple prefix in their name.

The Simple AY Interface is – of course- a simple AY interface for 16/48K Spectrums from 2013.

And in the 2014 designed Simple SAA Interface uses the SAA1099 chip of SAM machines for sound generation.

TwinSound, alias SAAY Interface is the combination of the two above. Beside the controlling CPLD and two audio chips, contains only a few additional components. So far, there is only news about a 2015 year prototype 1.

Finally, Simple Joy Interface was originally launched as a Kempston compatible unit with reset button, again from 2013. Its further improvement already supports the Fuller standard, selectable with a jumper.

Added: 2018. July

ZX ExpBoard Interface
Simple AY Interface
Simple SAA Interface
TwinSound Interface prototype 1
Simple Joy Interface

Pera Putnik's expansions Serbia Spain Sweden Czech Republic Italy Slovakia

Pera Putnik is one of the oldest Spectumist, who started his DIY website with various developments in the new age. Primarily mass storage devices are in the centre.

Among the smaller developments, there are various ROM modifications (as external ROM, Flash EPROM and switchable ROM), NMI button, RGB connector, floppy interface (which unfortunately uses its own file format).

He becomes well-known from his IDE interfaces. The simply Pera Putnik IDE interface called device has two variants. First one is 16 bit, the second one is using 8 bit technology. The one and only disadvantage of the 8 bit system, that capacity of hard disk will be half of the nominal. But in the case of ZX Spectrum, this fact is easily ignorable. The teenager developments works fine with modern Flash and Compact Flash cards - last one needs a CF-IDE adapter of course. Transfer speed is around 150K/sec, which is more than enough for Spectrums. ZX Spectrum +3e is also supporting these devices.

Listening to the voices of technology, also engineered his own Compact Flash interface. This is also 8 bit system, and using the full capacity of the cards. Based on the 8 bit IDE interface.

For this section can be connected the ResiDOS operating system developed by Garry Lancaster, and by the 8-bit interface used in ZX Spectrum +3e. Finally, became an universal operating system, that supports a wide range of Spectrum mass storage drive interfaces.

Compatible with Sami Vehmaa’s ZXATASP, ZXCF, ZXCF+, ZXCF+2 interfaces and also with the CF and USB modes of ZXMatrix. Supports DivIDE Plus and Velesoft's DivIDE expansion, the ZXMMC/ZXMMC+ interfaces and ZX-Badaloc clones as well.

In case of MB-02+ interface needs at least 256K RAM expansion and the MB-IDE card too, which is already built into the MB02+IDE. It also works when using standart MB-02+ connected with DivIDE. The own RAMdisk of MB-02+ can not be used in this case, as it would overwrite the OS.

The operating system is basically a Basic expansion, which is using the IDE interface and extra memory of the cards at the same time. Its operation is essentially installing itself into the RAM of the interface along with the modified Spectrum ROM. It contains a complex task manager also, which can be activated with the NMI button.

Installation begins with downloading the appropriate TAP/TZX file for the interface. Have to loaded in the converted real tape format installer into the Spectrum, or in the case of DivIDE+ and Velesoft's expansion, can be started right from the storage disk, then it will overwrite the actual operating system. For upgrading, original tape file is no longer necessary, from any of the interfaces can be loaded the .TAP or .TZX files. Or will you have to use the Basic install part and the card-specific C-language code.

Starting from version 2.00 can handle two kind of partition schemes. First one, the native IDEDOS that is the operating system of ZX Spectrum +3e (includes the original +3DOS too). For FAT16 the FATfs package is required. Using both operating systems simultaneously is also possible. First can handle 16MB partitions, while the latter one is obviously up to 2GB ones. "M" drive is the RAMDisk emulator, that works with both 48K and 128K modes.

Thanks for ZX Badaloc clones, supports the turbo mode, from 3.54 to 42.50MHz, the latter speed rate is still experimental. In the RAM of interfaces alternative ROMs can be stored. Functions of ResiDOS can be upgraded with downloading and installing packages. Latest version also supports SDHC and SDXC cards up to 8GB capacity.

Simple 8 bit IDE interface

Pavel Cejka's expansions Czech Republic

The Czech Cygnus, alias Pavel Cejka also offering some self developed hardware, which documentation is available on his website.

About his own versioned Miki RS232 interface we could already read.

The ZX IDE Interface is very similar to Pera Putnik's, although the author is suggesting the use of DivIDE interface. Anyway, it works without problems with ZX Spectrum 48/128K+2 and Didaktik Gama 89 machines as well with Beta interface. But it is doesn't like too much the Multiface 128 and Diskface plus interfaces. The available software is in Czech language, and supporting all basic functions.

Also giving some ideas to connecting ZX Spectrum and LCD monitors. On the homepage, there is a detailed description, how to succeed to connect a Spectrum with a Playstation 1 LCD screen. Anyone, who would like to connect any type of LCD monitor to the Spectrum, worth to read to avoid some traps.

A really innovative novelty is the connecting of PCL printers. Spectrumists were dreaming about the possibility of colour printing. But with the exceptions of some colour matrix printers there were no choices. Matrix printers are noisy, printing speed is low, and also the quality is far from the perfect.

As Cygnus is working as a service technician, got positive experience with the PCL language printers, so targeted these ones. He was designed a special Didaktik inverter PCB, to which is connected to a Canon standard parallel port (not Cnetronics, because Canon is more easy to finalize).

Due to the PCL language, all HP printers with LPT port made between 1995 and 2088 will work, but primarily works brilliantly with DeskJet 340. In theory, works fine with the printers of another brands too.

The drivers are supporting the 75-300 dpi resolutions, normal and draft modes, as well setting up the margins.

At last, but not least, we will get some ideas to work with the Aritma 0507 plotter. This is an old Czechoslovakian plotter, which was released in some variants, but they are differing from each others from minor details.

The plotter is connecting through the UR4 interface to the Spectrum. It has two superior technical details, which are better, than its contemporary machines. First, it using 1x8 bits to control all motors, while others are using 3x4 bits for each ones. Another, that it is using the more reliable screw mounting for the pen.

Cygnus was tried the most different printing techniques and sharing them with the publicity. He is printing with the original MZR driver from BASIC, making vector drawings with the Desktop software, and also using the serial port of SIF.

His 3 channel DA converter for UR-4 is a 3-channel, 8-bit ACB stereo device. It has 3 channel, because it is connected to the UR-4 interface, which itself also has 3 channels.

This is advantageous, for example, because the AY music has also the same channel allocation, so compatibility between the players and editors is solved. However, some of them use only the lower 4 bits, so the music is played quietly. Therefore, there is a separate 4-bit mode switch for all three channels.

When playing Amiga modules, channels are only 7 bits, because the middle C channel is divided into two, as the .MOD files are 4 channels.

When he was thinking about the creation, the small size, ease of production and cheapness were the main points. That is why the PCB has become one-sided, with only SMD 0805 resistors aside of switches, connectors, and a few wires.

After a decade, he was built a smaller, 50x50 mm version for the Didaktik Gama 192K (3 channel DA converter for Didaktik Gama 192K).

3 channel DA converter for UR-4
3 channel DA converter for Didaktik Gama 192K

Petr Simandl's expansions Czech Republic

Petr Simandl was begin his computing career with a ZX Spectrum 128K+2A. But not only played games with it, but also designed electronic circuits and making music with it.

Let's begin his hardware development with the +2A/2B floppy interface. It is built around the Intel 8272 floppy controller, and turns a +3 from the above mentioned machine. Anyway, the circuit was originally released in the 1989 December issue of Amaterske Radio. Thanks to its small size it is easily fits into the box of the big Speccy. Philip Mulrane was further developed it as ultimate +2A/2B floppy interface in the form of an external device.

The 4 channel D/A converter sound card for ZX Spectrum 128K+2A and UR4 is a 4-channel Covox, so actually a Soundrive mutation.

It has four 8-bit D/A converters and it is connected to the UR-4 parallel interface. Of course, also compatible with the ZX Spectrum 128K+2B/+3. It did not widespread particularly, on the one hand, because it uses double-sided PCB and on the another, its operation is unstable and does not provide good sound quality.

Also was born a more simple 1x8 bit AD/DA converter, which he was used with Specdrum.

He made the stereo-tuning of the AY-chip too, we can also found a circuit diagram for it in the website.

+2A/2B floppy interface
4 channel D/A converter sound card
for ZX Spectrum 128K+2A and UR-4

Philip Mulrane's expansions Great Britain

Philip Mulrane was reconstructed the already existed floppy interfaces. His first work was a +D clone from 2001. It seemed simple enough to build it according the public diagram on the WOS. Just obtaining two chips could cause problems, the the WD1772 floppy controller and the PAL20L8. You can try the WD 1770, VL1772, WD1791 or WD1793 ones instead of first. The other may be replaced with GAL20V8. Also necessary to obtain the 27C128 EPROM.

The goal was to create such PCB, which has the same dimensions as the original, yet doubles its features. Together with Harald Brunig, using the Protel software the board was ready. After creating two prototypes, they manufactured it with PCBPool company.

After implanting the components, the clone unfortunately did not work. He got an original +D from Peter Rennefeld, the member of Spectrum Profi Club. It was turned out, that the circuit diagram on the WOS was wrong, the address lines of RAM and EPROM was swapped, as well need to use the controller's A3 and A4 lines instead of A0 and A1. After correcting these errors, was born the perfect clone, and on the website, this corrected diagram was published.

Philip was painted his interface to black, which may fits better to the Speccy, than the original white. The 32K +D EPROM utilizes the 8K segment between 24 and 32K. Very probably MGT was bought a bunch of faulty chips, which is work in this region.

In the following year, his another development was also a floppy interface. It is based on Petr Simandl's unit.

He was modified the original PCB and realized in an external form instead of being internal as the original. In addition, he was added Garry Lanchaster's ZX Spectrum +3e HDD interface into it, and this way was created the ultimate +2A/2B floppy interface.

A little modding must be made, if it is used with a single 3,5” drive. The 3” drives has a 'ready' signal, which indicates to the controller, that the floppy drive is ready to send and receive data. In the case of 3,5” units this is mising. Therefore on this drives must be connected the select0 (pin10) and ready (pin34) lines. When using double drives, this is unnecessary, because the signal is always present in one of the drives.

+D clone
Ultimate +2A/2B floppy interface

Paul Farrow's expansions Great Britain

The English Paul Farrow is best known as a ZX Interface 2 expert in the Spectrum community.

These cartridges are not very well known, so begin this section with some introduction about them.

The 16K ROM cartridges fits into the special slot of Interface 2, was released on the market in September/October of 1983. In a sense, they turn the Speccy into a 'gaming console' - with zero loading time and zero loading error. Despite these positive things, not widespread very much, because 48K games became mass dominant. On the other hand, the loading time of 16K games was much more shorter - so did not worth to switch as an option of the tape. Sinclair Research also released a Test cartridge for diagnostizing the faulty Spectrums, these were used solely by the service centres. The Parker brothers produced some prototype cartridges too, but they were not public released.

Originally, cartridges contained a single 16K ROM (Standart 16K ROM Cartridges - method 1.).

The simple design of cartridges makes it easy to reproduce similar devices. The shortcomings of Interface 2 can be compensated by modifying the 'inner circuits" of the original cartridges. So the 'magical' 16K limit is easily breakable.

One of those facilities, when burning more 16K ROMs into a larger capacity EPROM and then select from them the desired ROM content (Shwitched Bank Paging ROM Cartridges - method 2.).

The next method is to read and map more single 16K ROMs into the RAM, then put them together into a single file. This was first used by the Spanish Insidro Nunez, who burnt the Knight Lore game into a 32K EPROM (Timed Bank Paging ROM Cartridge - method 3.).

A more advanced method the software controlled reading-mapping technique, instead of the previous method, when timing was controlled by the electronic circuit (Software Bank Paging ROM Cartridges - method 4.).

At last, it is possible to enhance the previous functions with the possibility of re-programming the Flash EPROM directly from the Spectrum. Then the maximum ROM size is 128K due to the limitations of Spectrum's memory (Programable Software Bank Paging ROM Cartridges - method 5.).

Paul made four separate generations from the cards: ZXC1, ZXC2, ZXC3 and ZXC4. These are available as empty PCBs, ready-populated PCBs, cased PCBs and ready-programmed cartridges.

The characteristics of different generation are the following:

ZXC1 is handles the 1., 2. and 3. methods. Supports 8K, 16K, 32K and 64K EPROMs. Two subvariants were produced: first batch has silvered edge connector (ZXC1 silver), the second got goldened (ZXC1 gold) to improve elelectric contact (otherwise, the two PCBs are identical). Was released in 2004.

ZXC2 (2008.) supports 1., 2. and 4. methods. Possible EPROM sizes: 8, 16K, 32K, 64K 128K and 256 K. In addition, it supports re-programbale 128K Flash EPROMs - but it is only possible to program them with an EPROM programmer.

The next generation is ZXC3 from 2009, which extends the capabilities of ZXC2 with the possibility of re-programing the Flash EPROM directly from the Spectrum. The card utilises the 5. method, as well the standard and simplified 4. method. 8K, 16K, 32K 64K and 128K EPROMs are supported, and it is backward compatible with ZXC2 up to 128k. With a simple modification, ZXC3 also can be enhanced to 256K. As mentioned above, in the case of ZXC3 does not need an EPROM programmer. Via the RS-232 port binary data can be sent to Spectrum. From that point, the Speccy can program the content into the Flash EPROM. For ZXC3 also available a Microdrive emulator ROM, which offers 75K storage by the BASIC commands of Interface 1.

In 2013 was released ZXC4, which is able to use 256 banks, reaching 4096K maximum, comparing of ZXC3's 128K. In addition it is capable to access the whole 16384 bytes, opposite of the ancestor’s 16320. Another novelty is to simulate the paging mechanism of Interface 1, so we can get 4 megabytes of FlashROM. It is usable as either as a Microdrive or cassette tape simulator. All ZXC is compatible with the Spectra interface.

For all of these cards usable the Windows-based ZX Cartridge Utility. With this, .Z80 and .SNA files can burn into the EPROM with an EPROM programmer.

The SPECTRA interface is a multi-purpose interface for the 16K/48K ZX Spectrum. Its primary function is to allow the Spectrum to be connected to a TV via a SCART socket to produce an RGB picture that is sharp, bright and completely free from dot-crawl.

SPECTRA interface plugs into the expansion port of the Spectrum and connects to the TV using a standard SCART cable. There is no need to make modifications to the Spectrum since the interface only requires access to those signals available on the expansion bus. The Spectrum's sound is also directed through the SCART connection to allow it to be heard loud and clear through the TV speaker(s). The clarity of picture and sound is equivalent to that only seen when using the monitor socket of a 128K Spectrum or a Spectrum emulator.

An exciting additional feature of is its ability to extend the Spectrum's display to support 64 simultaneous colours and at a variety of increased vertical resolutions, resulting in a total of 32 different display modes! Support is also provided for multiple screen banks, similar in concept to that featured on 128K models. At long last, the limited colour abilities of the Spectrum can be overcome, opening the potential for new visually stunning programs.

It also provides the following: a Kempston joystick socket, a ZX Interface 1 compatible RS232 socket, ideal for connecting to a printer, modem or a PC, a reset button, optional support for a ZX Interface 2 ROM cartridge socket, optional support for an onboard ROM to override the internal ROM. Further features: the ability to extend Spectrum BASIC via a ZX Interface 1 compatible paging mechanism (offering the potential to extend BASIC with commands to drive the new display modes); a rear, full width gold plated expansion bus, a set of configuration switches to allow each new facility to be enabled / disabled, ensuring full compatibility with all existing hardware.

All features come as standard, apart from the ROM cartridge and onboard ROM facilities. These are mutually exclusive and so it is left open for the user to fit whichever socket (if any) they prefer. Should you wish to use a Zero Insertion Force socket with the onboard ROM facility (useful if you intend to develop your own ROM software) then it is best to fit a turned pin socket first and plug into this. A standard IC socket is more suitable when you don't need to change the ROM very often.

This interface is constructed from a professional made board that measures only 10cm by 10cm. The interface will only operate with 50Hz models of the 16K / 48K Spectrum.

It may prove necessary in Issue 1 and 2 Spectrums to fit a wire link inside the computer to ensure a required video signal is exposed on the expansion bus (this optional wire link was fitted as standard in later builds of the Spectrum).

Later was realized the Spectra+128 interface also, which is compatible with 128K and 128K+2 machines. With the usual interface converter also compatible with 128K+2A/+2B and 128K+3 (we can found circuit diagram for example at Velesoft). It utilizes the shadow screen of 128K machines. As a result, with the appropriate software, you can even receive images on two monitors at once (Spectra Scart + Spectrum RGB). The cartridge port is standard in this case. The regular Spectra interfaces can be upgrade into Spectra+128.

Another area of DIY section the Scart leads for the various machines. Of course, we can buy them ready-made (see later), but there are full documentation for tinkering to all machnies including 128K (both UK and Spanish version), 128K+2, 128K+2A/B and 128K+3.

At last, there is information about how to rebuild the 'mysterious' Keypad (the attachable numeric keyboard) from contemporary parts. This one is originally designed for the Spanish 128K, but excellently works with the UK version as well with the 128K+2. He was realized it on a simple veroboard, but the printed circuit diagram is also downloadable from the website.

Updated: 2015. October

ZXC1 silver
ZXC1 gold
Spectra interface

Insidro Nunez's expansion Spain

After we meet all five methods, follow the evolution through the hardware development. Droy's (Insidro Nunez) first invention was a 32K cartridge. In this a 27256 type 32K EPROM was used. This storage was divided into two slices with a jumper (or alternatively with a switch). With this, the JetPac and Pssst! Placed into the 2x16K version using the 2nd method.

Possible the further development in such way, that one 32K program loaded instead of two 16k? The answer: yes. But this needs such programs, which are not using the lower 16K. The author was tried it with Knight Lore. The method is the following: first we read the first 16K. Then 3 seconds break. In this time will be copied into the dedicated memory segment this 16K part, and after that, the top of that will be placed the same sized next segment. The PCB remained the same, but it needs the 27128 EPROM and a delaying circuit instead of the jumper (or switch) in order to work the 32K version with the 3rd method.

The ZX-Flash Card from 2005 based on Jose Leandro 's work. With this 10 pieces of .SNA files can be stored in the 29F040 Flash EPROM, and send them into the memory of Speccy. The method is the following. First we copy the original modified (but compatible) ROM. Then select the program we want to load. At the end of 16K segment will be placed a pointer, which shows where memory place have to copy the next part. The last part contains that code, which unifies the three parts, and launches the program. The Windows-based ZX-Flash Creator utility was made by Miguel A. Prada. This was realized with the 4th method.

What to do, if we have cartridges, but no Interface II? If we do not need the joystick port, quite easy to build one. All you need two ISA slots, wires and some plastic skirts to prevent short circuits. Speccy contains 56 contacts, divided into two rows. These must be soldered with the cartridge's one. Worth to delete the unused contacts, to minimize the chances of short circuits in the case of Make it yourself Interface II.

The +D floppy interface was already mentioned. For the purpose of more simple manufacturing, Droy was divided into two single-sided PCBs his own +D clone version. First module is the controller unit. This responsible for controlling the shadow RAM and ROM, and decoding the I/O tasks. The second module is the adapter, it controls the floppy and parallel port. It works with both DD and HD drives. In the last case of course it needs to jumper them into DD mode.

Although much more another PC-keyboard interfaces are exists, the IMAR-3 is a totally own development. Its hearth is a 16F84PIC microcontroller, which is essentially a microprocessor with a Flash EPROM. 'Edit' mode can be activated with the F12 button, Interface II joystick is simulated with Alt and cursor keys. It is compatible with AT and PS/2 keyboards only and not with the XT ones (although who would use them nowadays?). In order to better compatibility with Ultimate games, the 74LS245 chip was replaced with 74LS148. It contains a thoroughgoing Sinclair edge port, of course it can be abandoned, if we do not need it. Only compatible with 16K/48K/48K+ machines, 128K ones are not supported.

Aside of the above adapter, he has some another tips for repairing the weak point of the Spectrum, the keyboard membrane. He is suggesting to repair the cracked ribbon cable with silver paint. This fixes the cracks on the faulty wires. Also suggests to apply adhesive tape to make it firmer. For sure we can verify our work with multimeter. Also we have to take care not to make short circuits with the paint. Although the manual of the paint suggests to cleaning with alcohol, we can easily damage the good sections also with it.

Also we can fix the too short ribbon cable. All you need is to cut an old PC's adapter bus connector, and solder the wires onto it. On the picture seen the servicing of a ZX81, but of course The Spectrum's method is the same.

If the keyboard matrix is totally faulty, we can rebuild the membrane with micro-switches. It is worth to use 0,7mm thick PCB instead of 1,6mm one regarding the tight place in the Spectrum. The author only could obtain the 1,6mm version, so the project was realized with this. After drilling the holes of micro-switches, must make the circuit of the membrane into the PCB. Then to solder the switches, and finally put it into the Spectrum.

Another option is making a totally new keyboard from an old PC's keys. The method is similar to the previous one, after the drilled and prepared PCB must built the keys into it. So we can avoid of modifying the Spectrum. The project was made for the Jupiter Ace, but can be applied to the Spectrum too.

All above that, some error detection and servicing tips also on the webpage.

32K Cartridge for IF2 2x16K version
32K Cartridge for IF2 32K version
ZX-Flash Cart
Make it yourself IF2
+D clone
Repairing cracked ribbon cable
Elongation of short membrane cable
Recostructing of membrane with microswitches
Making new keyboard

Jose Leandro Martinez Novellon's expansions Spain

After Droy, Jose Leandro Martinez Novellon was released the Super Cartridge for Interface 2 based on the second method. It was developed in two different forms in 2004. The first one, the TTL based only reach the prototype level. Because the TTL not able to give compact realization. Programs are stored in a 29F40 512K capacity FlashROM. The GAL chip version is the same as the previous, but integrated into a single chip. So become possible the compact size, fits well into a Supertronic PP40 or PP56 box. So it can be flawlessly usable with the original interfaces. The card is capable to store 15 programs, from which we can choose from a software menu. From these, 10 is the original ROM game, and 5 another extra 16K ones was also burnt in.

It was the inspiration of the ZX-Flash Card

He was also joined into the ZX Spectrum +2e/+3e project. But was unsatisfied with the continuous noise of the winchester, and that it needs a power supply. So he voted to Compact Flash card. First, he was tried with CF-IDE interfaces, from that came the idea of making an integrated device. The external CF-IDE interface is connected to the Sinclair edge connector, and built into a PP6-N box. Also got a bugfix, thanks to Aitor's suggestion.

In the case of 16/48K(+) models not so easy to change the factory ROM to EPROM. The ROM replacement project gives detailed information how can be replaced the original ROM with 27C128 (16K) or 27C256 (32K) EPROMs. When once opened the Spectrum, worth to change the welded ROM slot into a replaceable one.

The External ROM interface is similar to the previous one, and based on Julio Medina's 'amazing machine'. The disadvantage of this and the previous one, that very few people wants to tinkering in the Spectrum. Although it was born earlier, because its more advanced design, described later. The interface is connected to the Sinclair edge connector, and the external and internal ROM can be selected by a switch. Also got an extra reset button. The 76x51,5 mm size was due to fit into the PP6N box.

Also worth to mention the PS2 gamepad adapter among his own developments. With the conventional Spectrums suggested to use with Interface 2, and in the case of 128K+2/2A/2B/3 must take care of the different joystick port layout. The hearth of the controller is the PIC16F877 unit, but works fine with any 16F8X7. Communication is done by the program written by Bruno Fascendini. Both joystick ports can be used simolutesosly, the another port controls the extra buttons. The easiest way of feeding with power the interface and the controller through the joystick ports, as the power consumption is as low as 25mAh. Also works fine with the Guitar Hero and Dance Carpet peripherals.

When trying to load programs into the Spectrum from modern devices, such as PC, MP3 player, the success is questionable. It is because the modern age players do not providing the signal strength of the old tape ones. On the Internet, numerous circuits available of low power amplifiers, and they are also commercially available.

The Ear input amplifier from 2010 is based on the LM380 chip. It contains a potentiometer which controls the strength of the incoming signal, and Joe was fixed it to 70 ohms. To eliminate the background noise, also got a 47pF condenser. To verify the strength of the output signal, was built in a KA2284 chip. This controls the VU unit, which is optimal, when the three LEDs are lighting.

Two prototypes were made, first was aimed the minimal size (54x43 mm). The second was made directly for the PP42 box in 64x55 mm.

All above that, we can found informations from devices of another Spectrum fans, as well some repairing tips.

Super Cartridge for IF2 TTL version prototype
Super Cartridge for IF2 GAL version
External CF-IDE interface
ROM replacement
External ROM interface
PS2 game adapter
Ear input amplifier

Gondos Csaba's expansions Hungary

Gondos Csaba (GoCom, Gondos Computer Communication) is the main constructor of Sinclair.hu and also a radio amateur. His first interesting development is the ZX Spectrum Smartmedia interface (ZXSM) working with 8, 16 and 32 megabyte cards. It needs to modify the ZX Spectrum ROM routines. On the homepage also can find some utilies and source codes for the interface software.

Csaba was also realized the more, selectable ROM Interface 2 peripheral, the ZX Spectrum Interface 2 Multirom. Price of the device was 6000 HUFs (approx. 15-20 Euros).

It was developed in 2003 and has more hardware and firmware versions. Their common point, that ROM-sections were placed into 16K segments, so they applies the 2nd method.

First version were contained the ROMs in 128K or 256 EPROMs, from which one is the loading module, where we can choose, what ROM segment we would like to activate. After loading it, it is prohibiting the ability of paging, so the machine only sees the actual 16K part. First 8K containing the loader program, second 8K is responsible for the paging algorithm.

In the second version only occupies 256 byte the paging algorithm, so the loader can be more complex.

In the third version, only the 3FFFh memory address part is retained for the paging process.

Can be used 128, 256, 512 and 1024K-s EPROMs with jumpers. So maximum 64 pieces of 16K pages are available. With using the 1024K version, the possibility to switch back to the original ROM is missing, so the 3FFFh address will present on every pages. Anyway, in the 256K version can hold all commercially released ROMs.

About the published firmware versions. The v1.2 was released in the same year, as the hardware. V1.3 (2005.) got new screen and some ROMs were change also. The cartridge now contained the Shadow of the Unicorn ROM, the only game ROM, which has its own special ROM; the ZX81 and ZX81 ROMs, which are useable in 128K mode, and emulating fully those machines. Also placed the GW03 Spectrum ROM improvement, and finally, the actual ZXSM (smartmedia card interface) ROM, for those, who do not wanted to build it into the machine.

In the newest, v1.4 a very rare – and commercially not available – ROM was also built in, the Sinclair System Test, which was only available for services at its time. And also we can found the ZXSM ROM update (v1.2).

Another two novelties, the G-Tech interface (ZX Spectrum analog joystick IF) and ROM-extension are connected to the game Ghost Castles from WSS-Team. G-Tech interface connected through the Kempston interface, and supports analogue joysticks. ROM-extension is a 256K extender attached to the Interface 2. Only this game is supporting yet. All documentations are freely available.

The next two peripherals are quite similar to each others. Their joint feature that they are working as a 'digital tape', but they look like a different peripheral. TZX mouse is a TZX player with 8 megabytes of internal memory, working from button battery and capable to handle maximum 256 files. With a battery, averagely lasts for 100 hours, and also supports turbo loading up to 4x speed. This TZX-player was introduced on the Megabit-X 2010 club meeting.

Joytape player is also a common development with WSS Team, the special version of TZX Mouse, and was debuting on the same meeting. But it was ready as a prototype built into a garage bell box in 2009. Integrating the thing into a joystick was the idea of Gyorgy Papp (Pgyuri) as the creation of the name of the device also. The device priced at 20 Euros (4999 HUF), and certainly contains all WSS game pre-installed and also a bonus one. Its operating time approximately 1000 loads with the built-in battery. Also an inner beeper was built-in, and the EAR cable is a standard accessory.

Another developments: reducing the power consumption in more steps and reconstructing the keyboard membrane from micro switches.

ZX Spectrum smartmedia interface
ZX Spectrum Interface 2 Multirom v3
G-Tech interface
ROM extension
TZX Mouse
JoyTape Player
Reducing the power consumption
Reconstructing the keyboard membrane

Scott Falk Hühn's expansions Germany

Scott-Falk Hühn from Germany among his numerous electronic projects also offering some development for the Spectrum.

The ZX Interface 2 - ROM module with 32 memory banks based on the 2nd method and utilizes the 29F040 type Flash EPROM. Anyway, any other compatible piece suits well, but the author was found this one is the most cost efficient. This has 512K capacity, so in theory 32 pieces of 16K ROM fits into it.

With a mechanical selector chosen the desired ROM content, which mimic like the original ROM for the Spectrum. It was made on a mini stripboard. If we did not found adequate donor for the connector, just reuse and old ISA card. The super-mini size was achieved by placing components even bellow the Flash EPROM.

Programming can be done even by the gadget and software found on the website. If we do not want to collect the ROM one by one, also we can download a subjective collection. This contains 16 pieces of ROM, so uses the half capacity of the nominal.

In the case of 16/48K(+) Spectrums the video signal is led into the TV-modulator, from when it was sent to the UHF channel. With modern TV-sets it is a clear disadvantage, as the picture quality is degraded. Because the video signal is present, worth to lead it out directly. Scott was fixed the RCA connector with two component glue. Some circuits found on the Internet, which are suggests to build an additional transistor for amplifying the signals. But the author got better quality picture without it. So was born the ZX Spectrum 48K video output hardware tuning. A very similar modding is done by Womble.

A very important and simple thing is missing from the Spectrum, namely the reset button. Although it is easy to restart the machine with interrupting the power, this is not the most elegant method. Much better to build a micro switch between the Z80 CPU's reset pinout and the grounding, an voala, the ZX Spectrum 48K reset button is done. The ground can be in different places on the different mainboards, the picture shows the Issue 4b. Fixing was done again with two component glue.

128K Spectrum has RGB output aside of the TV out. If we can, use it. But if no composite input on the monitor, as in the case of the author, time to tinkering. The poor quality of picture is caused by the D35 diode and R144 resistor. In fact, they are totally irrelevant parts, with soldering them out or cutting them can be reached much better picture quality. Quite interesting, these two parts was not built into the later Spectrums, achieving better quality.

Even be improved the quality, when separating the AY and beeper signal. Eliminating the C126 condenser in the same way, the picture will be clearer. This tip was suggested by Ingo Truppel. Applying the two modding together get the ZX Spectrum 128K improved video output name on the website.

The MIC output of the 128K audio has several disadvantages. Firstly, very unbalanced, as the beeper is noisy and the AY-chip is quiet. Secondly, it needs continuous plug in and out, when using tape recorder. The ZX Spectrum 128K additional sound output is a mini circuit, which solves the problem. It contains three resistors and two condensers, which controls the beeper, AY-chip and the MIC/EAR. The resistors are balancing the beeper-AY and MIC/EAR volume, and the two condensers are separating the MIC/EAR signals from the AY-chip. Sound is come from an RCA socket, which was built into the RGB and video out.

128K Spectrums were made in more different versions. At the moment, we look them from the viewpoint of Keypad and MIDI/RS-232 ports. Was made such a series, when the Keypad is Sinclair-standard square type, and the another is D-sub one (unfortunately the pinout is non-standard, but this is not so important). The moddings found on the website (ZX Spectrum 128K additional RS-232/MID/Keypad ports) turns the two Sinclair-standard sockets into D-sub (combi Keypad and RS-232), as well to standalone DIN Midi-out.

As I was mentioned, the 128K+2 gives much better picture than its predecessor. But it can also further improved. The 2N3904 transistor is too weak, which is responsible for the noisy and unstable picture. When we replaced it to a greater capacity BC548C (it is found behind the RGB connector), the quality will significantly better. Also can be improved the quality with deactivating the audio signal from the video, all we need to cut out the C31 condenser. All of those tips were arrived from Ingo Truppel. Just use the ZX Spectrum 128K+2 improved video output name, like the author.

The sound is much better on the one and only grey Speccy, but far from perfect. The AY-chip is too quiet, the beeper is too loud, the noise of tape loading is super-loud. The solution: simple change the responsible resistors, with which we can adjust the optimal volume values, and we have done the ZX Spectrum 128K+2 improved sound output modding.

He also offers some another minor developments. Let's see them. In the case of ZX Spectrum 128K+2 the author noticed, that connectors are fixed a bit weak. With the more times mentioned two component glue, it is easy to fix this problem.

With the same machine Amstard introduced the non-standard joystick port. Although the conventional joysticks can be plugged in, they work only in one direction without an adapter or the special SJS joysticks. After the modifications, port one became Cursor compatible, the second is Kempton with an additional small circuit.

The combi RS-232/Keypad connector is using the previously 'crap' Sinclair standard socket, glued onto the top of the original Keypad port.

The 128K+2 ROM was changed compared to the 128K. Of course, the copyright message is different, and the tape tester routine also disappeared. Some another changes are exits, for example the address of the RS-232 routines. The original ROM was replaced with a double capacity 64K 27C512 EPROM. In this, both of the Amstard and Sinclair ROM placed. With a switch can be selected the desired one.

ZX Spectrum 48K video output
ZX Spectrum 48K reset button
ZX Spectrum 128K additional sound output

Phil Ruston's expansions Great Britain

Among Phil Ruston's creatures we could read about the V6Z80P 'platform' as well the Pendulum card, which improves ZX Spectrum compatibility.

The SMART Card (Snapshot (loader) Multiple Alternate ROMs & Test Card) was evolved from a homemade diagnostic card. This was contained a Flash ROM and a discrete logic.

The current hardware is CPLD based, has 256K of Flash memory, 128K RAM, as well SD card and Kempston joystick socket, with added reset and NMI button. It is targets such gamers, who want to play immediately after powering up the Speccy and they want it to be cheap. It loads an .SNA file within five seconds.

It is basically a multi-ROM selector. The firmware contains the manager program with which we can load, copy an delete programs into the FlashRAM. The author was installed its own diagnostic program. It support the .SNA files, and many .TAP files are also usable.

The card is compatible with ZX Spectrum 48k(+) machines. Also works with 128K ones, but they can not be connected physically. So if we open the cases, will work (can not be more simple ribbon cables?). On 16K models only the DiagROM works.

The first serie is made on green PCB, the second on blue.

Here we also can found tips for making composite video output for the ZX Spectrum. He describes two subversions: a condenser type and a capacitor one.

The condenser variant is more simple, it is compatible with most TV-sets, but maybe the picture will be a bit dark. The transistor one gives better picture quality, but do not works with every TV. The good news, that if done carefully, all of two are reversible. We can found detailed infos for making them on the website, and of course, every parts can be obtained though the webshop.

The 128K+2 often mixes yellow/cyan shadows into the RF and composite output. The inductor and condenser inserted into the TEA2000 video circuit can successfully reduce it. It can be bought in 'set' as 15uH inductor and 82pf Capacitor for Spectrum 128+2 Video mod.

Added: 2015. July.

Pendulum v1.1
Pendulum v1.1b
SMARTer Card

Aitor Gomez Garcia's expansion Spain

Aitor Gomez Garcia's Internal CF-IDE interface project is the marriage of Garry Lanchaster's internal ZX Spectrum +3e/+2e interface and Jose Leandro's CF-IDE controller. Unfortunately last one was only compatible with the SanDisk brand units, so it was buggy. The solution is quite simple anyway: the BC327 transistor and the connecting 100K resistor must be replaced to a single 10K resistor (Jose was later corrected this error).

The controlling unit was also redesigned into a more cost-efficient one, based on Lanchaster's internal unit. The Compact Flash adapter was built into the cassette player of 128K+2. To be sure, he left open the possibility of tape (MP3;) loading with a jack connector. The controlling unit fits into the Z80 socket, and the two parts connected with an IDE cable, which feeds the CF-IDE adapter with power.

As it is also a 8 bit interface, the capacity of the cards will be half of the nominal. Aitor was proposed to construct a switch, with which we can choose the lower and upper 8 bit parts. So could be utilized the full capacity.

Internal CF-IDE interface

Ben Versteeg's expansions The Netherlands

From the hardware stuffs of the Dutch Ben Versteeg we already spoken. Only to call up the informations again, let's talk about once again the things, which are realized by the international co-operations.

He planned to improve the originally Czech developed MB-02+ disc interface with the name of MB-04, but Ingo Truppel (with who he is in friendly relation) overdriven him.

The similarly Czech Velesoft's Kempston Mouse Turbo interface is producing in small quantity with attaching English instructions and an optical scroller mouse in the deliver pack.

The external version of Spanish Rodriguez Jodar's internal PS/2 interface is also taken into production.

Recently, he thinks about integrating the previous two boards, so maybe we except a mouse+keyboard combi interface.

Through his blog can informed the latest news, and the actually ready assortment is advertised through EBAY, and he delivers by post the ordered goods.

Even further, created a stereo converter for the 128K Spectrum. This is a mini PCB, which is placed on the top of the AY-chip. The card supports the ACB and ABC stereo standards, we can choose by shorting or by a switch between them. The beeper is coming from each channel, volume is fixed.

Despite, that it gives crystal clear sound, got fairly much negative comments on the WOS forum. So Benji stopped its development. Anyway, the series of the first line is ready, and the documentation is available from the homepage.

The idea of ​​ZX-HD interface goes back to June of 2015. That time Ben wanted to develop a HDMI interface. He was contacted Imre Jakli just then, who came up with the idea of a DVI interface, as the HDMI being a license holder.

At this time the Raspberry Pi Zero came into their view, which already contains the HDMI output. This was seemed good for controlling for I/O devices and replacing the ULA. So Imre started working on the firmware. By leaving out the operating system, this work was lasted for 6 weeks, although ULA emulation was not perfect yet, was ready in January 2016.

Meanwhile, Ben began coding the CPLD firmware. This was necessary because the ZX and Raspberry voltages are not fully compatible and the I/O operations can be more efficiently implemented by the CPLD rather than the Pi’s processor. The connection of these two works was resulted in the interface, and among the planned names ZX HDMI, ZX-HD, ZX DTV, ZX-PI-TV was chosen the second.

During 2016 the CPLD was fine tuned. The interface automatically detects the type of ZX Spectrum by the clock freqencty, and indicated by OSD for the suggestion of Imre. Subsequent experiments were followed, such as increasing the clock speed of Raspberry B.

Then they both ordered a Zero, which has higher clock speed, but only has one core. Imre optimized the code to such an extent, that he was able to trace ZX Spectrum video output on the Pi on base clock speed without frame skipping. So it follows the Speccy’s video output, from which it makes a mirror in the memory and then takes it to the HDMI output – all it was done with a single core. They also wanted to synchronize ZX-HD with the ULA, as quite a lot demos are using the so-called border effect, and that was succeed at 99.99%.

After that Imre tried to simulate the shadow screen of 128K (aka GigaScreen). Since Spectrum changes 50 times in every second the picture, this buffer can not be realized with HDMI. Instead, Imre simulated this with the interlace mode, which will automatically activated if needed (of course it is also possible to set it as default). This mode is activated after four normal-shadow changes. If it is over, the original mode will be restored.

ULAPlus support has already been solved. Unfortunately, Timex and HAM256 and HAM 8x1 modes are not yet supported.

Plans including - when a more powerful Zero will came out - the implementation of sound and other I/O devices also. Firmware update also very easy. Just download the ZIP file from the website and extract it into the root directory of the SD card. This will automatically overwrite the old one. CPLD firmware update is less regular, this is possible with the interface returning to Bytedelight.

The interface was successfully tested with ZX Spectrum 16K/48K(+)/128K /+2/+2A /+2B/+3 and the Harlequin clone as well with some other variants. Unfortunately, with Pentagon it does not working. Among the factory interfaces, Interface 1, Microdrive, Interface 2 and Kempston Joystick expanders have been tested. IF1 may have minor problems. Among the newcomers, it is compatible with ZX-AY, DivIDE, DivMMC EnJOY!, DivMMC EnJOY! *mini*, PlusDlite and K-Mouse Turbo devices. Compatible modes can be setting up using DIP switches.

The set is including the interface itself, a micro SD card with an SD adapter, installed with the firmware, and a mini-HDMI to HDMI converter cable. The Raspberry Pi Zero has to be ordered separately because of HDMI royalty rules. When installing, first step is to solder the 2x20 needle spindle to Zero. ZX-HD has been realized on two separate PCBs to make it easier to ship. After connecting them, Zero must be connected to the top PCB. Then insert all by four screws into the box and finally plug in the SD card.

This is followed by turning on the TV, then turning on the Spectrum. This will automatically detect the current machine, which will also indicated along with the current screen mode. The audio output have to be resolved separately, from HDMI not yet supported.

After improving the screen quality, audio output was also improved. The ZX-AY interface is similar to the 128K Spectrum’s circuit. It contains an AY-3-8912 chip and a beeper, but still offers some pluses. For example, ABC or ACB stereo modes can be selected with a balanced volume inluding the Beeper. This is, of course leaded into a stereo jack and can be configured with jumper. Fully compatible with all factory Spectrums and also with some clones. Obviously, works perfectly with the interfaces made by Benji.

The Stereo Kit can be used with any 128K ZX Spectrum. The circuit offers crystal clear and balanced AY sound, the same Beeper output on both channels, including Load and Save functions. The ABC/ACB stereo mode can be selected with a jumper just like before. It requires some soldering skills. The 1, 4, 5 and 6 legs of the AY chip must be pre-soldered. Additionally, in case of +2A/2B and +3, the lines responsible for mono output, also must be cutted. Then the kit have to be soldered to the prepared legs. For the aforementioned machines, two extra resistors are required: for +2B: 820 Ohm, for +2A and +3 machines with 2,2 KOhm capacity. Finally, the two cables must be connected. In case of 128K and 128K+2 machines, for ULA legs 34 and 35. At 128K+2B, one wire to the C202 and C204 capacitors, and in the remaining cases to the resistors R63 and R64. The final step is to drill the right space for the stereo connector.

The K-Mouse Turbo 2017-LP is the new, low-profile version of the Kempston Mouse Turbo interface (LP=low profile). Compatible with all factory Spectrums, with some clones, and most USB mouses using PS/2 protocol. Extras are including a configurable joy interface supporting Kempston, Sinclair and QAOPM, Space combos, which can be selected by jumper (in case of +2A /+2B and +3 only Kempston works). There is also a reset button on it. Its is Atari standard but two fire buttons can be used. Compatible with Sega Genesis gamepad too.

It is also possible to set the speed of movement of the mouse in case of three buttons devices, and it is able using of two mices in master/slave configuration at the same time.

In addition to the standard thoroughgoing edge connector, there are two other one prepared for soldering. The original, factory-soldered one is the same as the Sinclair edge connector. In the second case, RAM and ROM operations are disabled, only I/O operations are enabled. Third slot is freely configurable.

Regarding of the above developments, may not be surprising of a born of a Kempston joystick interface, which is the smallest such unit manufactured so far. The unit sold since June 2013 also includes a through-going edge connector and a reset button. Compatible with among others the original Spectrums, the DivIDE and DivIDE Plus interfaces.

The ZX Spectrum +2/+2A/+2B/+3 joystick adapter and Atari compatible joystick tester is a two-in-one device.

Because of Amstrad manufactured Spectrums are working with their own SJS joysticks due to different pinouts, that’s why this device was born. It converts these pinouts, so any Atari standard joy can be used.

Any 5-15 volt external power source can be used for testing. Directions are indicated by blue, the fire button by a red LED.

PlusDlite interface is based on the PlusD unit of MGT. This, as well as his big brother, the Disciple, were the best disk systems in their time. They were quick, had logical BASIC instructions, provided widespread drive compatibility, and the disks could be formatted up to 800K.

In addition to the factory specifications, Ben"s unit has a Kempston joystick port, reset and NMI buttons. The parallel connector however is missing.

Works well with Shugart and PC-compatible floppy disk and with floppy emulators as well, we can also use DD or HD disks. You can even order a dual floppy drive from the webshop. It is 16/48K(+), 128K, +2, + 2A/B and +3, and Multiface compatible.

Compatibility with the Kempston joystick and the Amtrad-derived Spectrum can be solved using DIP switches. The unit is shipped with a DD system disk. Its operating system is G+DOS, the Gordon Disc Operating System. A 3D printed case is avalailable for it. Of course, can be ordered already in the case. In addition, also with double floppy along a network adapter which is compatible with the customer's country.

Opus discovery upgrade packs released for upgrading the 3.5-inch floppy system originally was came out in 1985.

First set contains the 6116 RAM chip as well the v2.31 QuickDOS ROM. The previous is made for using Double Desnity disks with up to 800K capacity instead of Single-Desnity ones with 250K. If you want to operate it with a 128K machine, ROM replacement is also required to version higher than v2.22. This will also make the system faster. Contents of the second set is the same, but there is a floppy drive and a spare floppy cable also. Third set has a double floppy disk drive.

The Harlequin Superfo clone, which is a subsequent development of the ULA-free Harlequin clone developed originally by Chris Smith is also on offer. With the Harlequin Kits, we can assemble our 100% ZX Spectrum 48K compatible clone ourselves. In three sets can be ordered the most stable G revision.

The small Harlequin kit contains the motherboard only with the three SMD parts soldered on it. So other parts should be purchased by ourselves. This is also possible from Ben.

In case of large Harlequin kit, all components are soldered onto the system board, except the original ZX Spectrum ROMs.

With the assembled Harlequin board, we get a completely finished motherboard, also with the exception of ROMs. This has to be ordered separately due to copyrights laws. Og course it is possible to use alternatives, for example the ZX Spectrum (E)EPROM.

Speccy Breadboard is a blank experiment card, which can be connected to the machine via the edge connector. All the pinouts of connector are present and labeled on it. It comes with a 65 piece wire set. Its original developer Shaos, who is originally Russian, but currently as member of the NedoPC working as Ternary Research Corporation in Colorado. More information here.

The ever-needed keyboard membranes are also available. For the 48K machine it is available just as as for the 48K + and 128K versions, even with the the computer case.

New power supplis are also available for these machines as well as for 128K+2. But have to wait for the computer cases with backlit keyboards.

In addition, we find refurbished motherboards with composite video output. There are also chips and other accessories that can be useful for servicing and tinkering.

Added: 2018. February

ZX-HD HDMI interface prototype
ZX-HD HDMI interface
ZX-AY interface
K-Mouse Turbo 2017-LP interface
Kempston joystick interface
ZX Spectrum +2/+2A/+2B/+3 joystick adapter and Atari compatible joystick tester
PlusDlite floppy interface
Assembled Harlequin board Rev. G.
Speccy Breadborad v1
ZX Spectrum 16/48K membrane by Ben Versteeg
ZX Spectrum 48K+/128K membrane

Jose Leandro Novellon's expansions Spain
Gamepad PS2 adapter is connected to a ZX Spectrum+2A

The also similarly Spanish Jose Leandro Novellon is again offering some good ideas to enhance the ZX Spectrum with various interfaces.

Let's study first his RAMJET interface clone. The original one was the development of Microsat Hardmicro released in 1990 in Spain. Was planned for the ZX Spectrum +2A/B and +3, unfortunately will not work with the earlier models. This is a Multiface-like device, we stop running programs, insert pokes, and can save the programs to either to tape or disk. So, the Spanish solved the problems of the copy-protected disks. Jose not only cloned the card itself, but its box is also very similar to the original.

The external interface ROM is supporting the use of custom ROMs, without tinkering inside the Spectrum - can be gentling for those, who always planned a similar extension, but do not wanted to hurt the Spectrum. With a selector switch we can choose between the original ROM and the EPROM, and got an NMI and reset button additionally.

He is an enthusiastic user of Garry Lanchaster's ZX Spectrum +2E/+3E clone, but like another users, was irritated by the use of power supply and the noisy operation. That's why he changeover to the Compact Flash cards. He describes three submethods of using them. Fist one is using a simple CF-IDE adapter for the already available board. Its main disadvantage, that the CF card still must be feed from external power source.

So made some own constructions, which named jointly to Compact Flash +2E/+3E interface. First version included the IDE controller and the solution of power supply on the same PCB, but without the CF slot. Immediately constructed an inetrnal and external version. Further development of this card is a complete interface, which integrating also the CF-slot on the board.

The gamepad of Sony Playstation 2 also successfully connected to the Spectrum with the Gamepad PS2 adapter. This using the two joysticks ports. Author is suggesting the use of Sinclair 2 compatible interfaces, but theoretically compatible with all types. Works smoothly with Dance Carpet, but has some problems with the guitar of Guitar Hero.

Also cloned Interface 2 cartridges, the TTL version was soon followed by the more compact GAL chip variant.

All above, some smaller or bigger own modifications (faulty sound jack and PAL chip replacement, ROM exchange) and analysis of classical devices also can be found on his website.

Aitor's expansion Spain
Pera Putnik Simple 8 bit IDE interface Compact Flash version 2 internal bugfixed

The again Spanish Aitor's internal IDE interface is based on the card of Jose Leandro. After a simple bugfix, and learning the low cost finalisation of the board started to construct it.

The interface is mounted into a 128K+2A machine, into the place of the cassette unit. To be sure, built in a jack connector, if sometimes want to load from tapes.

The card must plugged into the socket of Z80 processor. At the moment, this one is also only uses the half of the nominal capacity of IDE devices, as it is an 8 bit card. Aitor wants to further develop it with a switch, with which easy to choose between the low 8 bit and high 8 bit areas of the card, and accessing the whole 16 bit capacity in this way.

PCWKing's expansions

Great Britain

The English John R. P. King (or as he calls himself: PCWKing) principally well-known about the tune-up of Amstrad produced computers. So, among the whole range of CPC, PCW series and the NC100 machine, also using the ZX Spectrum +2, +3, +2A and +2B.

The DIY section can be divided into two sub-parts in case of the Spectrum: making of various cables and modification the Achilles-point of +3, the floppy system.

The first cable is a monitor cable for attaching CPC monitor for the +2, +3, +2A and +2B. Well, this is basically a converter cable between 8 Din (Speccy) and 6 Din (CPC) connectors, which gives superb picture with the CPC unit. Unfortunately, sound is not driven by this method.

Similar is the RGB-Scart converter cable for +2, +2A and +2B machines, this was designed by Alan Cox. It also contains some resistors. Opposite of the previous cable, this also contains the sound output (in mono). The picture is far superior, which can be obtained on a monitor.

The next DIY cable is Centronics cable with which standard printers can be connected to the Amstrad-originated Spectrum models.

The last cable (which is also the most simple one) is a tape cable for the +3. Here a stereo jack is converted to two mono ones (MIC and EAR).

The another area may catch the interest of +3 owners is the different floppy disc modifications.

The most simple one is the external 3 inch drive attachment method. For this only need a standard PC 5,25 inch cable floppy cable, from which maybe cutted down the unnecessary second floppy connector.

Adding a 3,5 inch unit is muck more trickier. As 'modern' 1.44M and 720K drives working solely with 5V, the 12V line line from Spectrum must be cutted down or must be fitted a 5V regulator.

Another difficulty, that not all 1.44M drives are working fine in 720K mode, as they missing the 'Ready Signal' (this is indicating, if there a floppy disk in the drive or not). For testing this feature, there is also a hint on the homepage.

The next problem is if we have the compatible floppy drive, that they will use 180K as standard. For solving this problem, there is also a simple side switch circuit on the homepage. This issue is also can be solved with a ROM replacement.

Módosítva: 2010. augusztus 07.

Graham's expansions

Great Britain

ZX Spectrum +3e mod 1st version by Graham

Graham also primarily focused on the Amstrad manufactured machines, and also made modifications for attaching an external floppy drive. Opposite of PCWKing, he not only trying out the possible compatible 3,5' drives. He went further, and constructed his own disk-ready -> disk-change signal converter board. With this, easily can be compatible with all floppy drives the ZX Spectrum 128K+3.

Construction is quite simple, based on a 74LS38 type logical gate. By the way, for the another retro (made before 1990) computers the circuit works fine. If not so, with utilizing the rest gates of 74LS38 there is also possible solution on the webpage.

In addition, Graham also introducing a regulator circuit, which solve the 5V power supply needs of the floppy drive.

He also worked on the further development of 128K+3e. For starting point, used the Pera Putnik simple 8 bit interface. For the first attempt, the power needs for the HDD of an old laptop is feed from the power connector of the Speccy's PCB. The shortcoming of this method, that during power on, the hard disk do not get enough power to spin up fully, so the +3e will not recognize it. It can be solved by pushing a simple reset.

In the second version, the winchester was replaced with an 512K micro memory module, which is an early version of SDD. This has low power consumption, and has no spin-up time, so adopting the previous method, no need to reset after power up. The circuit remains the same, only the socket of card became vertical.

After upgrading the ZX Spectrum 128K+2 to +3e, in this machine was moved the old laptop hard disk. The power now comes from the CPU.

Also we can read about a 128K+3e modification for the ZX Spectrum 128K+2. The size of the original ROM of +2 is 32K, and +3 uses 64K ones. As these old ROM modules can not be bought as new, Graham used a 128K EEpROM. For building this modification, also necessary a 28-32 pin converter. We can choose with a switch from the extra ROM the necessary ROMS: 48K, 128K+2 or 128K+3e.

Updated: 2010. September 26.

Branislav Bekes' (z00m) expansions Czech Republic

Bratislav Bekes from Bratislava (z00m, Z00m) is known as the composer and graphic designer of Total Computer Gang and the member of MB-Maniax team. With his hardware developments, of course, also dealt with the compatibility of the Czech/Slovak Didactik clones and D40/D80 interfaces.

The LED memory map was developed jointly with Busy in 2005. It contains 64 LEDs in a row or in 8x8 matrix. Each LED represents 1kB, which light up, when the CPU reads from them (very useful for cracking).

Beside of ZX Spectrum and its clones, can theoretically work with other 8-bit micros as well. The wiring diagram was optimized later in 2009. Using this design, Ik0n was improved a bit of it and created a two-color matrix in 2010 (dual color modification, bi-color modification). Red color indicates the writing, the green one the reading.

The construction is possible on a universal DIY card or on the prototype PCB of the authors. Can be used as an internal interface or can be built into another interface (MB-02 +, Betadisk, + D ...).

A parallel development with this the Bank LED map, which indicates the operation of the 32765 port. Can be installed into the ZX Spectrum 128K and 128K+2 machines.

The pictures are showing the first version. The circuit diagram of the new version is slightly different, but its function is the same (2005 and 2010). The first eight red LEDs are indicating the memory segments, the next one is the normal/shadow screen indicator, then the ROM and paging on/off is displayed. Z00m has not placed the LEDs on universal DIY cards, but directly glued into the case of 128K+2 Spectrum. This two can also be used together, of course, for 48K machines only the previous one.

The Simple AY interface is based on the idea of ​​MDV. The ABC stereo mixer is using the 'golden ratio' method of Zilog originally developed for ZX Spectrum 128K+2 machine.

This two parts were unified in 2010. Have to simply place the components on the universal DIY card and wiring it. The AY chip is crystal controlled, so the clearest AY sound also guaranteed by this.

The circuit was redesigned by MDV in 2014 to be compatible with Didactic Kompact machines and D40/D80 disk units. Can be used as an external or internal interface.

Pavel Urbancik edited a neat PCB for it, called as Nice board. There are two revisions exists, so the first was released in 2010 and the second in 2014.

The year 2010 D40/D80 modification for 128K and 128K+2 machines is also based on the idea of ​​Zilog (although many others have made similar changes). After a simple conversion, you can choose between standard 128K and D40/D80 compatible modes with a switch. The key element is when you are using the disk interfaces, the modding activates the ROM of 48K machines.

Based on this, Tritol has made the D40/D80 modification for 128K+2A and 128K+2B machines schematic diagram for the later, black machines.

The MB-02+ modification for 28C256 EEPROM from 2013 has been mentioned at the MB-02+ section.

In 2017 was the Melodik2 AY interface released, which is a redesign of the original. The PCB can be easily mounted into the original case.

The control logic has been further developed in order to avoid data collision with D40/D80 interfaces. The ACB stereo mixer is using the previously mentioned Zilog’s golden ratio method. The frequency of AY-chip is also crystal controlled here. There is also a line out for Didaktik Kompakt. The power is filtered for even clearer AY sound. There are two sub-versions, the first came out in 2015 and the second in 2017.

Added: 2019. April

Memory LED map
Bi-color segment modification
Bank LED map
Simple AY interface
Nice board
ZX128K and ZX128K+2 mod for D40 D80 cooperation
MB-02+ modification for 28C256 EEPROM

Petr Kouril's 's repair, mods and extension Czech Republic

Petr Kouril (PedroS) was sadly constated when was prepared for ByteFest 2010, that the keyboard of his ZX Spectrum was did not working. With more close inspection, he saw, that the ribbon cables were cracked at the connection. The folie membrane is otherwise fully functional.

So a patch connector had to be made. Before starting the operation, the heat-sensitive parts must be removed and advised to put them into an antistatic bag.

For the implementation, he was chose two 7-10-inch multi-wire cables, as the IDE one proved to be too rigid.

Soldering the cables to the connectors is the next step. This is followed by soldering the wires to the motherboard: the cables also must be mirror images of each other.

After that, only the assembly is remaining. Interestingly enough, in Brazil, Victor Trucco has used such a solution to solve the similar problem.

The Repair of ZX Spectrum Keyboard Inputs was first released on the Sindik.at website and later transferred to his own homepage.

Didaktik Gama is using an old-style power supply, that is heavy and prone to warming. It uses two types of voltages: one is the stable +5 volt, and the another is the unstable +18volt. The latter one is converted into stable + 12V inside the machine and powering the TV modulator. Anyway, the connector is of DIN type.

Because his plan was to replace the old power supply with a modern one, he was traced the way of +18V inside the machine. First, the color of the wires was strange. The yellow for +18V is quite normal, just like blue for grounding, but the green for +5V is unusual. Finally, it turned out, that it was part of a ribbon cable and they didn't want to bother with the right color scheme. The other oddity was the routing of the wires. The non-stabilized 18V passes directly near to the ULA and then contacts the 2/3 of the motherboard. It is converted into stable +12V in the upper left corner of motherboard, and then returns to the TV modulator on the PCB in the lower left corner of the board. This can cause unnecessary interference and instability, which is otherwise the weakness of these machines.

The plan was to replace the original PSU with a 1.5 amp +5V/12V Freecom GFP252-0512 power supply. When measured the power supply of Didaktik Gama, it was 17-18 volts, which goes down to 15v, when connected to the machine. At the place of stabilized 12V, measured 11.4-11.6 volts in the machine. These may be due to aging of the electronics or to the poor quality ex-socialist components. At the Freecom power supply measured +5.2 and +11.7 volts, the latter one was increased to 12V when connected. It could be read in the forums, that this is too little to pass through the stabilizer, so it should be used directly wired into the TV modulator.

He was tried out this method. The disadvantage of this, that the Didaktik can not be used further more with the original supply, although it can be easily redone - as we will see later, it was happened.

This was followed by constructing the Molex-DIN converter. The system was worked when tested, but a horizontal stripe appeared on the screen and DivIDE did not recognize the SD card. During the tests it was turned out, that the stabilizer works with any voltage, even with 12 volts, and the output will be stable at around 11,5 volts. So the new power supply can be used without the Alternative PSU mod for Didaktik Gama. After redoning the internal rebuilding, everything worked well, with the exception of some screen noises, which can be regarded as normal. DivIDE, however, still did not work, because for some mysterious reason the 5volt was went down to 4.4V.

He did the test with another power supply, with the Chase CAD12B type. Here, the +5V is goes down to 4.8v when connected, and +12v goes up to + 13,5v. DivIDE is not functional here either. After that, instead of taking the risk, he decided of using the original power supply.

Seeing at he Sindik.at meeting Mike's solution, he was decided to replace the original 7805 voltage regulator with something more modern.

His choice became the LM2596S with a mini SMD fan. This is not only suitable for the Spectrum, but also for another retro computers. Since there is little space in the rubber keyed version, the Plus has been chosen for modification. Although there are existing smaller versions, which are suitable for the rubber one, questionable, if they not causing interference. The output voltage can be changed either by soldering the appriorate jumpers (1.8V 2.5V 3.3V 5V 9V 12V) or changing with a potentiometer.

After the measurement, it was turned out, that the original controller operates at 5.06V. This circuit is 46 Celsius hot, moving up to 50 with distancing, this is not dangerous for the other parts. By the way, it keeps the 50 Celsius independently of the outside temperature.

This was followed by setting the measured output voltage on the circuit, Which got the ZX Spectrum DC Converter name in this case. Then was removed the original parts, and then wired the new one. He was measured 35 Celsius without load, and about 50 C when loaded.

Two screws were drilled into the bottom of the machine housing, and the slightly unneccesary bold wires were fixed with adhesive tape.

The idea behind the birth of Ultimate bus splitter for ZX Spectrum was the fact, that DivIDE does not have a through-going edge connector, so joystick interface can not be connected to it. The author wanted to use simultaneously the DivIDE, the UR-4, a Joy interface and an AY-3-8912 interface.

The base of the bus splitter was provided by an ISA bus hub from an old machine, from which he was made an edge-to-edge hub.

The first step was to purchase from Noby's webshop the edge connector mini PCB. Then the 16-bit ISA connector parts removed along with the electronics and then he was formed the psyhical bumpers.

In order to attaching without physical collision, he was removed the unnecessary ISA buses, and finally put a PCI-Express bus on top.

After some debugging, the splitter was born. It works perfectly, but when multiple peripherals are used, the voltage drops from 4.95 volts to 4.87 volts. This leads to some loss of stability. This can be eliminated by raising the voltage of the inverter, but Petr did not deal with it separately.

Added: 2019. February

Repair of ZX Spectrum keyboard inputs
Alternative PSU mod for Didaktik Gama
ZX Spectrum DC Converter
Ultimate bus splitter

Skoti's expansions Poland

The name of Skoti in Poland was already got known at the ZX Spider clones. His another creation, the Kempston+AY interfész (aka KAY) is a combination of a Kempston-compatible joystick and an AY interface from 2018.

The card, which is based on an AY-3-8910 (compatible) chip, has a 3.5mm stereo jack providing ABC or ACB stereo output. The Kempston part can be configured to be compatible with Timex computers. There is also a reset button on it.

Added: 2019. February

ZX Spider 48 rev 1.1
ZX Spider 128 rev 1.1
Kempston+AY interface

Maciej Gruszecki's expansions Poland

About Maciej Gruszecki's (pear) Chrome 128 clone we could already read about. He was made several another smaller, but useful developments, which he was shared with the members of Speccy.pl virtual community.

The AmpY stereo AY Amplifier was originally designed for ZX Spectrum 128K+3 in order to eliminate the factory defective AY music. Later, several other variants for the ZX Spectrum 128K, +2, +2A/B and CPC6128 were released. The device itself is mini-card, which can be plugged into the place of the AY chip. A beeper in/out with a mixer is connected to the ABC or ACB stereo AY part. The device must be separated from the motherboard with an adhesive tape.

The board for ZX Spectrum 128K is the smallest. The beeper must be connected via resistor R112.

For ZX Spectrum 128K+2 Issue 1 and 2 machines, the volume difference between the AY and the beeper can be balanced by replacing the R61 resistor with a 8.2 kΩ one (they are in different places on the two mainboards). The beeper input here comes from resistor R38, and at 128K+2A, this input is R207.

At 128K+3, the TR5 transistor is the source of beeper sounds.

On the Speccy.pl Wiki page there are photos for the wirings for all machines.

The pEAR interface bearing the creator's name, is an EAR input mini-card for the ZX Spectrum 128K+2, +2A/B and +3. The idea was given by Joulesper Coulomb's ZX Spectrum 128K+2 Repair Youtube series. If our goal is not to repair, we can easily add a second input for loading programs (from phone, latop, etc.). Before assembling the machine, here also necessary to separate the interface from the keyboard with sealing tape, as they are too close together. In the case of gray and black machines, the electronics are the same, only the mounting/connection part to the cassette unit is different.

The pEAR 48/128 is the equivalent of this for 16K/48K/128K machines. It have to be connected into the place of previously desoldered R36 and R37 resistors, also taking out the TV modulator. It also includes an Aout output, which provides stereo audio output. The composite video out, which replaces the TV modulator, cannot be used with 128K, here you have to use an alternative solution.

Added: 2019. February

Chrome 128K Issue 3
Chrome 128K Issue 3A
pEAR for 128K+2
pEAR for 128K+2A/B
pEAR 48/128

Przemyslaw Krawczyk's (Lotharek) expansions Poland

The Polish Przemyslaw Krawczyk's (Lotharek) ↑DivIDE compatible interfaces↑, the 57c clones, the DivIDE 2k11, DivIDE 2k14, DivIDE 2k20 AY and DivIDE Revised, as well as the USB HxC and SDCard HxC Floppy Emulator already mentioned some paragraphs earlier.

The KempAY interface is his first own Spectrum related development, which was begin in November 2009. This is a combined card of a Kempston Joystick Interface and AY-card, and it is also Sinclair joystick compatible. The joystick part has only one connector. The AY-part is 128K compatible. Of course, it has a thoroughgoing edge connector. The further development of this card is KempAY CPLD, which was made with ATF1502 CPLD and contains a joy tester and a reset button. Got two RCAs instead of the stereo jack.

The interface is not available now, but sliced into two parts, can be ordered by anyone. WonderAY is a standard AY-interface. The price does not include the sound chip, but of course it is also can be ordered. A development from 2010. The Simple Kempston is a simple Kempston joy interface, just as the name suggests.

The Angry Space Invader from the end of 2012 (on white or black PCB) is a Kermpston and Sinclair interface. Again built with the ATF1502 CPLD and its extras again the LED joystick tester and reset button.

Specially for 128K owners was made the ZX Spectrum 128K/128K+2 64 KB SRAM replacement. This replaces the base lower (video)memory. Of course, first have to remove the original RAM modules, then to solder the socket of the device. After with seven pieces of short cables connect the PCB with the DRAM data lines of Spectrum.

Updated: 2020. August

Przemyslaw Krawczyk (Lotharek)


DivIDE 2k11
DivIDE 2k14
DivIDE 2k20 AY
DivIDE Revised

Alexander Anatolyevich Shabarshin's expansions Russia United States

Alexander Anatolyevich Shabarshin, also known as Shaos, started his career with the ShaOS prototype operating system for 8-bit Intel 8080-based clones between 1992 and 1998. His name also is derived from the variant of ShaOS. In 2002 he was started the NedoPC group and to which several other members were soon joined.

In 2004 he was moved to the USA, first to New York, then to Colorado. Here he is working as Ternary Research Corporation. He develops various electronic devices, including Spectrum accessories. Products can be ordered through the online marketplace of Tindie Inc. Let's take a look at the widgets, which are interesting for developers.

On the ZX Breadboard Adapter, the pinouts of the edge connector are leaded out, marked the functions of each individual legs. Its primary goal is to test the new Spectrum expansion cards. It is useful for example with the following products.

With the ZX Speccy Breadboard allowed to soldering of wired periphery prototypes. On both sides of the card there are also the edge connector pinouts. It is vertically oriented as default, but can also be ordered in horizontal design. From 2017, it uses yellow PCB as a result of a uniform appearance, rather than green. It can also be ordered from Benjamin Versteeg. There are also different versions for both ZX and Nemo bus.

ZX Speccy Extender is an empty prototype card. This allows you to create the soldered prototype before the PCB etching.

With the help of the ZX-fixer, you can connect your old peripheral devices to ZX Spectrum 128k +2A/+2B and +3. The task of 2x8-pin DIP resistance is to prevent data collisions and the two diodes are converting the signals.

The Eagle source files are freely available for each projects.

Of course, we can order ZX Spectrum edge connectors also, which are manually cutted, very probably from old stock ISA-buses.

Added: 2018. May

ZX Breadboard Adapter
ZX Speccy Breadboard
ZX Speccy Extender
ZX Fixer

Victor Trucco's expansions Brazil
Beta 128 Plus


As in the post-states of the former Soviet Union the Beta-128 disk interface became dominant, it became in Brazil its predecessor, the Beta-48. Trucco was dealt with both of them, let’s see the results!

The author chosen the IDS 2001 clone for rebuilding. Jorge Braga was written its documentation, so Victor wanted to contact him. However, there was no answer, so jointly with Flavio Matsumoto prepared the PCB for mass production.

Already the first prototype was good quality, but in some places had to be redesigned to make more room between components, thus easier to implant them.

In the first revision two islands left short-circuited, and a few other similar, smaller errors was occurred. In addition, the holes must be expanded. The biggest mishap, however, that a line is accidentally deleted from the drawing which was sent to the factory.

At last, the final version of IDS2001 disk interface clone was flawless for the first time, from which 60 pieces was made for the members of TK club.

Its further development the IDS Plus interface, which is the marriage of an SD card drive emulator and the IDS2001 disk interface clone in a Palace plastic box. The reasons of implementation, that the already existed Beta 128-Plus was only compatible with 128K machines. Not only the box, but the SD card reader part was inherited from the earlier born 128 version.

The Beta 128 Plus interface is the SD-card version of the previously mentioned Beta-128. This is based on Jorge Braga's 'wired' Beta 128 interface, after his friend, Marcus Garett sent him to repair.

After repairing the interface, Victor made the PCB variant of it based on Braga's document. This is more neat, smaller and also more reliable.

The following minor modifications are making easier the life of (Brazilian) ZX Spectrum 128K+2 owner.

The first mod is a simple one with the purpose of making available the Spectrum work with 110V power supply (which is the standard in Brazil). This type of supply can be bought nearly everywhere, but the Spectrum needs reversed polarity. The most simple way to rewire the supply itself, but it means the lost of guarantee. Instead of this, he is suggesting too crossing of LK5 and LK6 jumpers inside the Spectrum to achieve the desired result.

The missing power button is one of the faults of the manufacturer. It would cost half pound, and would not be necessary to plug in and out the power connector.

The tumbler was placed under the cassette unit. Must take care to put it as low as possible not to disturb the mechanic of tape recorder.

If the reversed polarity mod was not made, LK6 jumper must be deactivated. Useful to glue the wires to the bottom of the machine box not to run into the parts of the tape recorder. It is purposeful to lead the wires to the mainboard under the heatshink.

He is offering two methods of making composite video output.

The "1a" variant of the tuning is more simple. Looking near the RF modulator, we have to see a TR4 transistor, 3 diodes (D7, D8 and D9) and a 75 Ohm R12 resistor.

For first, ZN3904 transistor (TR4) must be replaced with BC237. Theoretically, they only differs in polarity, but BC237 offers better picture quality. Must be sure, that LK1 and LK4 jumpers are closed, and LK2 and LK3 are open.

Then desolder the small resistor inside the modulator, which brings the video output to the centre of connector. This is in a small plastic tube. After it, must be deactivate the two wires, which are connecting the modulator the the Speccy’s motherboard. Finally, connect a wire between the centre of connector an LK4 jumper.

Basically, we are ready, but there is still a problem. When the Spectrum plays music, this leading interference with the picture. This is caused by, that adding the sound to the picture is done before the RF conversion. Solution is simple: remove the C31 condenser, which mixes the picture with sound.

Also exists a different mainboard, which is very rare. Seems, it is an intermediate one between the ZX Spectrum 128K+2A/+2B/+3 and the original gray cased one. So, the "2a" version of the tuning can be also applied to the black models too.

We have to build a mini-circuit and the most convenient way to place it to the empty RF modulator. As the metal box is grounded, must take care, that the parts do not touch it.

From the two wires, one is the 12V, another is the video input. First one have to solder to the pin 11 of TEA2000, last one must be connected to the L1 resistor. Removing the condenser responsible for interference is the same, in this case means the C24.

Making of audio stereo output is purposeful to begin with the RCA connectors. Worth to place it near the power switch, place the longest distance from the mechanic of tape recorder.

This followed by lifting up the R37 and R45 resistors. After it, have to solder the cables, the author was used three wired grounded one, from which the third is unnecessary. The rest of two cables must be connected to these resistors, the ground to the R41. The other end of cables soldered to the RCA sockets. Take care of the length of the cables, again not to run into the mechanics of the recorder.

R37 controls the AY, R45 is the signals of ULA. Varying of these two resistors, can be controlled the volume of the two channels.

The next modification is the stereo output. First step is to separate the audio signals from the video signals. It needs to connect the R37 and R45 resistors. For setting up the required volume, it is suggested to replace the R37 to a 4,7 kOhm one.

Using of standard Atari joysticks he offers two solutions. For making the Atari compatible joystick connectors needs to tinker the machine itself and needs skilled technician, good quality tools and materials. First, the joy controller chip must be desoldered. Then cut the ‘joystick’ track between the joystick connector and the modulator. Finally, the pins of the joystick must connected with the keyboard matrix and ready the Interface II compatible modding.

Making of Atari joystick compatible adapter can be recommended for those who do not want to disrupt the machine. This is much easier to do, needs two DB9 connectors, a female and a male. All you need to do to to solder the wires according to the figure.

Although nowadays less widely used the original cassette recordes, using the EAR input not be completely forgotten thanks to the project as O.T.L.A., which in theory can increase the bit rate to 38400 baud instead of 1500. The downside of using audio files with MP3 players, that usually the volume is not enough for TK machines. Two ideas have been raised, if you do not want to use a dedicated mini amplifier box.

First is to bypassing the integrated noise filter in machine. As any MP3 player has much better quality than the contemporary recorders, so it's useless. Volume level is raising with 20-25%, which is in most cases can be adequate. For filter inactivation R40, R41 and R70 resistors and diodes D13 and D14 have to be removed, which are close to the EAR jack.

Second solution is the TK-Ear Reloaded circuit, which is based on an LM358 SMD. In addition to amplifying, capable of transfer more balanced signal.

TK-Ear Reloaded 2.0 was birth accidentally. Since the LM358 was not at home, so Victor built a modified circuit around the LM324. Surprisingly, programs were loaded at any volume.

32K High Memory SRAM Replacement can be either repairing or tuning. With 48K machines it replaces the faulty memory segment, with 16K ones expands the memory to 48K. First step is to obtain a 8 bit 32K SRAM memory. Then have to desolder the U21-U24 chips, which needs skilled person. After, depending on the size of the new chip, to the top of the ROM (full size chip) or to the bottom of it (half size) must be to solder it. And the final step to solder together the wires and set the jumpers. Memory expansion to 48K goes in the same way, but here must be soldered the 47LS32 and 74LS00 chips, which are controlling the upper memory area (by factory, a resistor is fitted instead). And finally only two resistors and condensers needs to be soldered and ready the fully 48K compatible machine.

One of the shortcomings of TK clones, the lack of RGB output. The ULA generates digital RGB signals, which is converted into composite video, then the picture goes out through the RF modulator.

Very few monitor able to handle digital RGB signal, so it is necessary to do analog RGB conversion. He was re-made the circuit of ZX Spectrum 128K + 2, even the 8-pin DIN connector is the same for the TK90X RGB circuit. The wiring diagram is otherwise the same as in the TKPlus project, however, the finalization is slightly different.

Using of the aforementioned composite video out signal as standard has some drawbacks. One of them is the poor image quality on modern devices, and the another is warming of the transistor. This is not causing problem, but worth to eliminate.

He was choose the 2N440 composite video signal amplifier proven in ColecoVision video out when creating the TK90X A/V Reloaded circuit. For even better results, was deactivated the R52 resistor, which is mixing the picture and sound.

Seems that using memory cards (instead of HDDs) were in the minds of oversea owners also, that's way were born the ZX Spectrum 128+3 CF. Alvaro Feeders sent a Victor a +3 machine, to make the video and music tuning. The machine was arrived without floppy, supposedly saving costs. After doing the moddings, followed by the building of CF cards. Victor was used the Pera Putnik 8 bit simple interface with the appropriate English language ROM. The card was inserted into the Z80 processor slot. First tests were done with using the CF-IDE interface directly. After the successful result, the CF unit (with some epox glue) was fitted into the place of floppy drive. The last task was to connect the parts with an IDE cable.

Updated: 2013. november 24.

Alistair MacDonald's expansions Great Britain

Alistair MacDonald is a software engineer, but despite this, mainly doing hardware developments. In his focus there are the Amstrad-era Spectrums.

With the external floppy connector of 128K+3 and 128K+3B easily can be connected 3,5” drives to these machines. This unit is present as 'B', while the internal remains 'A'. It is possible to force the Spectrum to use the external drive with a special cable. This is done by shorting the 'direct select' line of the external one. It has some disadvantages, first disappearing the possibility of automatic selection, and secondly could harm to the electronic circuits when used for longer period.

A much better option to make be switch-able the drive select line on both drives. This is the aim of the Drive swap switch on the +3 or +3B simple tuning. For this, each of the internal (drive0) and external (drive1) line must be cutted, and make switch-able the two ones with crossing the signal. And of course, be selectable the 'normal' and 'swapped' mode with a switch.

The ZX Spectrum 128K+2A and +3 was (in)famous about their bad audio amplifier. These were corrected in the later 128K+2B and 128K+3B models. It is possible to do this fix with the 'fisrt generation' machines, it is a kind of upgrade. For this must be replaced seven resistors and add further two to made the Fixing the sound on the Spectrum +2A/+3 hardware patch.

The Flash adapter for the Spectrum +2A/+3, +2B, and +3B is an add-on board, in which the content of two original EPROMs is placed into a single FlashROM. Also known as Flash Rom Replacement for the ZX Spectrum +2A/+3, +2B, and +3B. The mini card must be inserted into the place of the original two EPROMs. It has 128K full capacity, from which only see the half of the content the black Amstrad Speccys. The desired part is selectable with a jumper.

The first prototype is built with the W29EE011 chip. This was single time writeable, and needed an external burner (for example used with PC).

The base of the second prototype was the AM29F010B 128K FlashROM. All of two was made on tripad card.

Of course, the final version was made on professional PCB. It was available for 10 pounds, but now stock is out. Now burning can be done directly by the Spectrum, after write protection was disabled with a jumper.

The second edition is more cost-efficient in small series of production. Its hearth is a AM29F040B, which capacity is quadruped of the previous. If enough requests are coming, could be started the series.

The solution of audio problem and applying the FlashROM card together is a very important step to create the 128Ke machine, the idea of Andrew Owen, and which could be the ideal 128K machine. Owen was collected complete ROM sets, which can be downloaded from the website.

The essence of S-video out for the ZX Spectrum +2A/+3, +2B, and +3B, as its name suggests, to send S-Video compatible signals to the TV. But it is easy to damage the TEA2000 modulator when using it nonstartad way. So the authior is not recommending this mod, his own unit was also restored to composite.

For me the technical text is bit high, but must to cut the resistor between the LUMO pin (luminance out) and LUMI (luminance input), and applying some transistors instead them as buffers, and can we get clearer picture.

The ZX Keyboard project turns the (dead, but with good keyboard membraned) Spectrum to an USB keyboard. The device works in two ways. When single keys are pressed, the relevant HID code is transmitted. When Caps Shift is pressed, again the same happens as with a normal keyboard. Of course, the number keys are excepted, it sends the cursor, delete etc. signals. The commands and symbols accessible with Symbol Shift, divided into two parts: some goes out directly, another going out as 'converted' (for retaining emulator compatibility).

Nice idea, but the most criticized point of the Spectrum is its keyboard. But seems OK for emulator use. Anyway, it is based on the Arduino development platform.

Updated: 2015. July

Drive swap switch
Flash ROM adapter prototype v01
Flash ROM adapter prototype v02
Flash ROM adapter
Flash ROM adapter Second Edition prototype
S-Video out
ZX Keyboard

Mikhail Tarasov's expansions Russia

We have meet Mikhail Tarasov's (Mick) name multiple times. For example at ZXM-Soundcard series, ZXM-GeneralSound, as well with various clones, such as ZXM-Phoenix, ZXM-777, Pentevo Light and ZXM-Zephyr.

ZXM-Moonsound card is MSX-originated. First was appared as Moonsound on Tilburg computer fair by Henrik Gilvad. Its modern age reincarnation was came out in 2012, with Wozblaster name from an Argentinian fan, Gustavo Iriarte (Ciro). In the next year, Eugene Brychkov was modified so, to fit into a standard Konami cartridge.

In 2015 on the zx.pk.ru forum came up the idea of the realization of the Spectrum version with ZX-Bus. Due to the differences of two platforms, it is not controlled by GAL16V8 but by the Altera EPM7032STC44 CPLD. The most important part of it is the Yamaha YMF278 (OPL4) chip. On this card, it is capable of 18 channels of FM-synthesis and playback of 24 channels of 12 or 16 bit audio.

It has 1 megabyte of RAM and 2 megabytes of ROM. First can hold the user defined samples, last one contains the built-in General MIDI instruments.

Outputs: stereo jack, double RCA, four pin audio out. Four demo diskettes, and a 'service' one was released for the 24 pieces serie. Dmitry Pugachev (DJs3000) also gave advices for the development.

The primary aim of the ZXM-VideoCard is to able to connect the ZX clones to VGA monitor. The homepage also mentions 'advanced graphics capabilities', but no further mention about that.

There are also being development two another cards, ZXM-ProfCard and ZXM-LANCard.

To simplify of developing ZX Spectrum peripherals, also created a Devboard Z80 development card. It is a card equipped with Z80 (compatible) processor and Nemo-bus. The Altera EPM570 is Flash-based, so it has limited rewriting cycles. The card is capable to simulate every (future) peripherals, even can mimic a Spectrum itself.

The size of RAM can be 512-1024K SRAM, the ROM size is 512K. Picture output is VGA. It has standard PS/2 keyboard connector. The communication is realized by RS-232 serial port as well by an SD-card reader.

Updated: 2015. December

ZXM-Soundcard Extreme
ZXM-Phoenix rev 05.1
ZXM-Phoenix 2
ZXM-777 rev 01
Pentevo Light
ZXM-Zephyr rev 00
Devboard Z80 rev 00

Dylan Smith's expansions Great Britain

The first peripheral of Dylan Smith (Winston), the Spectrum Flash ROM and Diagnostics Board was built for the 25th anniversary of the Speccy in April 2007. Producing this card is 'totally free', as all documentations are available, and all software is freeware which is needed for creation.

The purpose of the card is if at least the Z80 processor is working; it examines the memory, ULA and the ROM. It partly communicates on the screen, but when ULA is faulty, problem can de identified by the error codes of the LEDs. The PCB is optimized for homebrew finalization (hand drilling and welding). The size of Flash ROM can be between 128K and 512K. So we can burn inside anything with a help of a (working) Spectrum.

The aim of Spectranet Ethernet card is to put the Spectrum online again. This was realized in the past with the Prism VTX 5000 modem and Interface 1, as well with the RS-232 port. Unfortunately, these methods are out of dated now, so totally incompatibles.

The card is built around the WIZnet W5100 single-chip Ethernet device. This was specially designed for embedded 8 bit systems, so ideal for the Spectrum. The controlling logic is done by a Xilinx XC9572 CPLD CPLD. 128K FlashROM and the same amount of RAM can be found n the board. First one can be programmed from the Spectrum, and various programmes can fit inside. The RAM is reserved for special programs, and also for general purposes. This card is also can be reproduced homemade, and also a free, open project. During the planning, compatibility was a priority. So it works fine with all Sinclair and Amstrad models, and also with the Interface 1, DivIDE(+) and joystick interfaces.

With is, can run Twitter client, IRC software, as well to play games on-line downloaded from WOS.

The SpectraDVI is still in a very early development stage. This is an ULA+ compatible HDMI interface with DVI-D connector and 480p resolution. It would be realized in a Spartan FPGA-6SLX9 as an external interface. Just plug in 48K, 128K, 128K or 128K, 128K+2 or 128K+3 machine, and it will work. It is possible that it will have a VGA output also.

The CPLD-based ZX breakout board is designed to provide access to the ZX Bus pins, and use them to further our projects. Whether the Xilinx XC9572XL or the XC95144XL can used to it. In the case of 128K+2A, 128K+2B and 128K+3 for the fourth pint must be disabled, all the rest Spectrums works perfectly without any change. The tool has been implemented in four-layer PCB.

The Spectramin a fun project, which is a Theremin controlls the AY-chip. The interface is based on the ZX Breakout card and uses the XC95144 CPLD.

It consists of two main parts: the Theremin, which is actually two separate Theremins each for one hand. The other part of the interface itself. The two Theremins controls the 1 and channel 2 (pitch and volume). There's even a foot pedal, which is slightly different from the Theremin concept, but Dylan do not have three hands. This can be used to manage the third channel and switch the musical instruments. It is advisable to operate it with battery, as the Spectrum's power supply is very noisy.

Updated: 2015. July


Piotr Bugaj's expansions Poland

His Beta-128 clone is based on the original. The schematic was acquired from Pavel Cejka (Cygnus) website. Compared to the original version, the system switch has only two modes: 48K and 128K. The reset operates separately as a microswitch.

Hozzáadva: 2010. július 10.

Beta-128 clone by Pavel Cejka
Beta-128 clone by Piotr Bugaj

Womble: 48K kompozit videó kimenet Great Britain

On Womble's Retro Repair Shack blog is published how to made a composite video output for the 48K (and thus for the 48k+) , which may interesting for a lot of owners.

The job takes up 10 minutes. What you need is a soldering iron and a 4cm wire. Anyway, another 10 minutes to reconstruct the original condition.

The trick is, that Speccy originally sends composite signals to the RF modulator, which is converted to RF signals. This is lead into the TV by the aerial cable, where the TV reconverts it to composite signals. This double lossy converting was necessary in the times of Spectrum, as TVs did not have separate AV input.

The advantage of Womble's picture illustrated modification -beside its simpleness- that it can be done without any psychical damage (drilling, extra screwing). By the way, the original documentation of this modification was released in a 1986 issue of Crash magazine. A very similar modding from Scott-Falk Hühn is also available.

Added: 2010. July 03.

48K composite video output

Alwin Henseler: SRAM replacement for lower 16k The Netherlands

In ZX Spectrum 48K(+) models the memory is divided into two parts. The upper 32K (2x4 ICs) is used solely by the Z80 CPU. The lower 16K (1x8 Ics) is shared between the ULA and the Z80. The errors of these chips often the cause of the non-working Spectrum.

How can the problem solved? It is seems simple, but there is a big problem. The 4116 DRAM memory ICs of Spectrum needs +5, +12 and -5V, and nowadays all available DRAMs work with simple +5V (the original DRAMs can not be bought as new).

So Alwin Henseler in 2009. February introduced the SRAM replacement for lower 16K repair tip, which is replacing the original chips with SRAM module. It has more advantage: first, it has lower consumption, which reduces the Speccy's heat output. And second, also fits fine into the place of the original chips.

The documentation gives detailed description of the modification as well the technical background. Alwin tested it with two types of SRAM chips, all of those were worked (in theory, all 70-150ns access time SRAM module will be fine). Anyway, the idea was based on Miguel Angel Rodriguez Jodar's earlier tip, which was used a SIMM module.

Added: 2010. July 10.

SRAM replacement for lower 16K

Click keyboard Italy

The Italian Electrons beside his another modifications, also take care of the Spectrum. His Click keyboard modification is replacing the keyboard folie membrane with pushbuttons.

This mod is made 'forever' and from outside it is invisible. But while typing, the rubber keys will click under your fingers.

For realizing this modification, you need 40 pushbuttons, plus recommended to build also a reset button at the same time. First you have to take apart the Spectrum. Then you have to drill holes into the centre of the key places of the 'key box'. After you have to drill holes exactly into the same location into a rigid plate. Onto this plate, have to glue the pushbuttons, then also fill the gaps between them with glue for improving stability.

Wiring the pushbuttons to each others can be made by using the keyboard folie membrane as a template.

For last, you have to solder the original connectors to the end of 8+5 wires.

No more steps, put again together your machine.

Added: 2010. June

Click keyboard

ZX Laptopok

Sami Vehmaa's laptop

Two ZX Spectrum laptops also saw the light, both of them are based on the 48K gummy version.

The laptop of srimech.com (Suburban engineering) was built on a Toshiba Libretto 110. The author was built in the gold old gummy keys, and the mainboard and screen remains from Toshiba. So, the main part of the work was to convert the Spectrum's 5x8 matrix to the laptop's 8x13 system. The computer is running Linux, so needed an emulator to feel like a real Spectrum.

Sami Vehmaa' machine is a real ZX laptop: the original machine with a 7" LCD screen, using Compact Flash card as mass storage device. On his website can access the DIY infos, and Sami can support LCD screens for request.

ZX Spectrum +128K

Great Britain

Richard Gellmann's ZX Spectrum +128K project is covers to made a homebrew ZX Laptop with LCD/TFT display, flat keyboard and modern storage devices.

The laptop is based on the ZX Spectrum +2 due its compatibility and nice features (such as RGB output).

The display is a 800x600 resultion TFT screen and .TZX files are stored on MMC card.

The computer will contain two custom chips. First one is ZX10701, which integrates the original ZX8401, PAL 10H8, 74174 and 74157 chips and also supports the NMI ROM.

Second is a ZX10702, which is a PIC16F627 microcontroller. The task of this to decode the signals of the PS/2 keyboard. It is used, because the PS/2 keyboard has numerous advantages comparing the original keyboard matrix. It is easy to replace and using the special keys (for example the multimedia buttons) is also a great feature.

Among the future plans there are a CMOS RAM/RTC and a mini LCD (date/time display, .TZX 'counter' etc.).

The file system is FAT16 and the FGPA-based VGA is a variant of Chris Smith's ULA clone.

Hozzáadva: 2010. július 26.

The Sinclair Shop

The Sinclair Shop is ran by Ian Priddey since 2004 and delivers to every part of the world.

Beside the Spectrum, offers ZX81 and QL accessories, even C64/128 and Amiga parts on sale. Of course, the parts of Amstrad designed Sinclair machines working well with the contemporary CPCs.

Most popular goods are the RGB Scart cables offered for all Spectrum models (thus these are manufactured in three subtypes).

Also spare parts in the warehouse: 48K tape lead, +2 tape and +3 drive belts, as well some types of transistors, diodes, plugs (serial, 9V DC, RGB Video, ZX edge connector). And there is +3 tape lead also.

The homepage is currently under development, presently we can do shopping through EBAY.

Sintech Germany

The German Sintech firm located Filderstadt lead by Thomas Eberle (EBI or FBI).

The on-line shop is handling new and retro computers, consoles and accessories. But the top of the hearth of Thomas there is the ZX Spectrum, which proven by the fact, he is the member of UVS (Users Vote Speccy) coding group and editor of the Scene+ tape and diskzine.

The Spectrum side of the shop offers relatively huge assortment. But it is only the surface, because a lot of goods are common stuff for the PC, Amiga and consoles.

Now pass round the specially ZX Spectrum accessories. Spare parts: TV antenna cable, 48/128K and +3 tape lead, and Scart-monitor cables for all types. Also there are power supplies for all Spectrums. The evergreen 48K and +/128K keyboard membranes offered too.

On the stock the internal and external versions of Proface AT. At the same way can be bought Spectrum keyword sticklers.

Sintech is still waiting for MB-03 pre-orders.

Some another tiny tots: video modulator for better picture quality, and an on/off switch between the Speccy and power supply.

DataServe Retro

DataServe Retro is a single person enterprise, which only handling 8 bit micros. Besides the buying-selling, also offering historical overview, and repairing and maintenance guides on the homepage.

This is a non-profit company. All items, which can be found here, fully restored and tested, so being in much better condition, than anywhere else we can search for.

Alongside of the used hardware, some new parts also available for the ZX Spectrum.

Certainly the 16/48K and 48K+/128K keyboard membranes are accessible. And can be bought the tape leads for these machines too.

Spare tape drive belt for all 128K+2 Spectrums, as well the 128K+3's drive belt can bought, and the tape leads for the last machine is also offered.

The TV antenna cable is fits for all Spectrum models, and also there is RGB Scart cable for 128K+2A/+2B/+3.

Thanks to buying up the old stock, some unused factory hardware is also available: 128K+2 and 128K+2A/+2B power supplies as well 3 inch floppies.


In the 2003 founded Clive.nl primarily was created to put into circulation ZX Spectrum and another Sinclair goods. Later they extended the assortment with Acorn, Atari, BBC, Commodore, MSX, Schneider and Tandy hardware, software, book and magazine section.

In fact, it is a retro collecting group, which sells out the duplicates. The on-line ordered things are posted by priority airmail.

Above the used items, they have some new ones for the Spectrum mostly cables.


The Informantica e-shop founded in 1999 besides supporting current platforms, also has offers for the fans of retro hardware.

In the case of Spectrum, it is the divIIDE+ interface, RGB cables suit for 128K+2 and +3 machines, as well the keyboard membranes of 16/48K, 48K+/128K.

Due to the Amstrad relationship, 128K+3 owners also shop their spare floppy drive belt and the ever rare 3" diskettes.

Some second hand Sinclair items also occur on the Ebay shop.

All Top Notch

All Top Notch is a small family run business manufacturing and selling audio-video cables and other accessories.

For the ZX Spectrum (and ZX81) also trading 2 and 4 meters long TV-cables.