In 1990 two of its designers from Leningrad, Dmitri Michailov and Michail Osetinskij, came by train to Bath to show Your Sinclair a computer they had built. It was called the Hobbit. It ran Spectrum programs, switched from Cyrillic to the Latin alphabet with one key, had a 74-key keyboard, a network port, disk drives and three joystick ports, and over 15,000 had been made for Soviet schools. Why start from the Spectrum? “In Leningrad, many people get out their soldering irons and make their own computers,” Michailov told the magazine. “The Spectrum is the most well-documented computer in the Soviet Union, so that is where most people start — there are now at least 20 different Spectrum clones in Leningrad alone.”
The Hobbit was one of a great many. From the mid-1980s factories, research institutes, co-operatives and hobbyists, above all in South America and the socialist countries, built their own versions of Sinclair’s ZX Spectrum. Alessandro Grussu’s Spectrumpedia catalogues more than a hundred of them, most from the Soviet Union and the states that followed it.
Why the Spectrum
The Spectrum was cheap, popular and well known, and it was small. Grussu describes Spectrums “often smuggled from the West” into the Eastern bloc, where, “due to their low cost and ease of use”, they spread until “local microelectronics companies made ‘their’ versions of the machine”. A computer that ran the Spectrum’s ROM could run its enormous library of games and programs, which arrived by the same unofficial routes.
The difficult part was the ULA, the custom Ferranti chip that generated the Spectrum’s picture and shared its memory. Many clone makers could not buy one, so they rebuilt its logic from ordinary chips. A Brazilian owner wrote to Sinclair User in 1986 that Microdigital had replaced the ULA in its TK 90X with “half a dozen anonymous chips”, and that this was why Elite and Tomahawk would not run on it. The Soviet Pentagon used about twenty chips to do the ULA’s work. Small differences in timing or in the input and output ports were enough to stop some programs working; the same letter warned that the TK 90X’s ports were “in different locations”, so British add-ons would not fit.
Licensed, grey and unlicensed
“Clone” covers several different arrangements, and Grussu sorts them. A few machines were authorised by Sinclair: Timex built the TC 2068 and TC 2048 in Portugal, and in India DeciBells made the dB Spectrum+ under licence in Pune. Poland’s Unipolbrit Komputer 2086, a version of the Timex TC 2068, was a rare semi-official machine in the Warsaw Pact, made by an agreement between the Gdańsk firm Unimor and Polbrit International, a Timex subsidiary. Some were built to get round copyright, such as Spain’s Inves Spectrum+. Brazil’s machines came from a “grey zone”, a country whose market reserve kept foreign computers out and whose law was less strict. And the Soviet Union, Grussu writes, recognised little or no copyright protection, so its clones were designed and built without any arrangement at all.
South America
Brazil. Microdigital of São Paulo, which already sold Brazilian ZX81s, launched the TK 90X in June 1985, according to Micro Sistemas: a Spectrum-compatible machine with a Z80A, 16K or 48K of memory and its error messages in Portuguese. The TK95 followed in 1986, in a new case and with a revised ROM for better compatibility. The TK 90X was also sold in Argentina and exported to Chile, Uruguay and Ecuador.
Argentina. Czerweny Electrónica resumed contacts with Sinclair Research in 1983, despite the tension after the Falklands war, and reached an agreement to make local versions of Sinclair’s computers, but it could not use the Sinclair name while Argentina banned British goods. Its CZ 2000 of 1985 was a 48K Spectrum built on boards imported from Timex in Portugal, with its TV output changed to Argentina’s PAL-N standard. Czerweny then made its own CZ Spectrum and, in 1986, a CZ Spectrum Plus with its messages in Spanish. According to Grussu, its plants made about 4,000 CZ Spectrums a month, until a fire destroyed the factory near Paraná in June 1986; Czerweny stopped making Sinclair-derived machines in September 1987.
Central and Eastern Europe
Czechoslovakia. The Didaktik Gama appeared “shortly before Christmas 1987”, the Czech club magazine Mikrobáze reported, made by the production co-operative Služba Bratislava at its Didaktik plant in Skalica. A television advertisement had the plant’s director promising plenty of software and hardware add-ons. The machine had extra memory and a built-in parallel interface, but those additions made it only partly compatible, and many Spectrum programs and peripherals would not work. Still, Mikrobáze noted, interest was huge, “and there is hardly anything else”. Inside, the Gama used a genuine Ferranti ULA. Its successor, the Didaktik M of 1990, used a ULA made by the Soviet firm Angstrem, and the Kompakt of 1992 added a built-in 3.5-inch disk drive. Didaktik stopped making computers in 1994.
Poland. In 1985 Poland’s Ministry of Education wanted an inexpensive school computer compatible with the Spectrum, because so much Polish software had been written for it. Mera-Elwro of Wrocław built the Elwro 800 Junior from 1986: a Spectrum-compatible machine with a 64-column text mode, a CP/M-compatible system and a classroom network called Junet. Buying it was another matter. In early 1988 Bajtek reported that production had started but that the ministry had not taken a single finished computer between November 1987 and mid-January. A survey of Polish secondary schools in 1989–90 found that 89 per cent of the schools using computers had a ZX Spectrum and 46 per cent the Junior, and that Juniors made up 42 per cent of the machines, ahead of Spectrums at 37 per cent.
Romania. ICE Felix of Bucharest made the HC85 from 1985, developed from work by Professor Adrian Petrescu at the Bucharest Polytechnic; the first version had to load BASIC from tape. Romania also had the TIM series, used mostly in schools, and the CIP machines from Electronica.
Hungary and East Germany. Hungary’s HT 3080C, offered to schools, added an AY sound chip and a Commodore disk-drive port but stayed a prototype when few schools chose it. In East Germany clones were mostly study projects at technical universities, such as the Grafik-Display-Computer from Ilmenau, built round the U880, the East German copy of the Z80.
The Soviet Union
The Soviet Union and its successor states produced more Spectrum clones than anywhere else. Grussu dates the great spread to 1988–1993, as Spectrum schematics circulated alongside machines that had been brought in illegally. Many were home-built, and many were made by factories turning from military work.
- The Byte. The electromechanical plant in Brest, in Belarus, sold the Byte (in Russian, Bayt) from the end of 1989 at 1,000 roubles, with a keyboard marked in Latin and Cyrillic. Production peaked in 1992.
- The Pentagon. Vladimir Drozdov built the first Pentagon in Moscow in 1989 and published it as an open design that anyone could build. A 1992 article in the Russian magazine Radiolyubitel, Grussu reports, traced the name to the circuit board’s cut corner, which gave it five sides. Most Pentagons had a copy of the British Beta Disk interface built in, and its TR-DOS system spread so widely, helped by the Pentagon’s popularity, that disks took over from the cassette tapes Spectrum owners used elsewhere. Retro Gamer found in 2005 that about 80 per cent of Russian clones came with a Beta Disk interface, and that the Pentagon 128 had been “basically a hand made computer that came in many forms”, from PC tower cases to “a collection of circuit boards and wires”.
- The Scorpion. Sergey Zonov of St Petersburg, who had already designed the Leningrad clone, launched the Scorpion ZS 256 in 1991, with 256K of memory, a hard-disk interface and later a 7 MHz turbo mode. Its fans and the Pentagon’s argued, in Grussu’s words, like supporters of rival sports teams. Zonov’s company stopped developing Spectrum computers after 1997.
- The Hobbit. Developed in Leningrad and made by InterCompex, the Hobbit was the first Soviet clone sold in Britain. In August 1992 Sinclair User listed it at an introductory £79 through InterCompex-ADB Russian Services of London, with a 640K disk drive for £59. Buyers waited: in December the magazine reported that the first batch was only now due from St Petersburg, and that cheques sent with orders had not been cashed.
In the file format
The machines left a mark in Spectrum preservation. The TZX tape format, which archivists use to preserve Spectrum cassettes, has hardware codes that a tape can use to say which machine it was written for. Alongside Sinclair’s own models, and its Spanish and Arabic versions of the Spectrum, the list names the Pentagon 128, the Didaktik M and Gama, the TK 90-X and TK 95, the Byte, the Elwro and the ZS Scorpion.
Later history
Several clones outlived Sinclair’s machine. Grussu describes the Pentagon as one of the most popular machines among Spectrum fans in the former Soviet Union, rebuilt again and again; in 2005–06 Alexey Zhabin of the NedoPC group designed the Pentagon 1024 SL, with 1 MB of memory and a turbo mode. Retro Gamer found the Russian Spectrum scene “still big” in 2005. The Brazilian line led somewhere unexpected: the ZX Spectrum Next grew out of the TBBlue, a Brazilian board based on Microdigital’s TK95.
Sources
- Keith Pomfret, “Rage Hard!” (the Hobbit), Your Sinclair issue 57, September 1990, p. 37: the visit to Bath, Dmitri Michailov’s quotations, at least 20 clones in Leningrad, over 15,000 Hobbits in schools, the keyboard, ports and network.
- Alessandro Grussu, Spectrumpedia volume 1 (English edition, CC BY-NC-ND 4.0): chapter four, “Clones”, pp. 341–473 (more than a hundred entries, arranged by country); p. 38 (Spectrums smuggled into the Eastern bloc, semi-official and unlicensed clones); p. 343 (licensed, copyright-avoiding, “grey zone” and Soviet clones; Beta Disk); pp. 344–348 (Czerweny); pp. 349–351 (Microdigital TK90X and TK95); pp. 352–357 (Didaktik Gama, M and Kompakt, the Ferranti and Angstrem ULAs, Didaktik’s end of computer production in 1994); pp. 358–359 (East German clones); pp. 362–363 (HT 3080C); pp. 364–365 (dB Spectrum+); pp. 366–369 (Unipolbrit Komputer 2086, Elwro 800 Junior); pp. 370–373 (Timex Computer TC 2068 and TC 2048); pp. 374–377 (TIM series, ICE Felix HC85); p. 404 (the Soviet clones of 1988–1993); pp. 407–408 (Bayt); pp. 421–425 (Hobbit); pp. 444–447 (Pentagon, the Radiolyubitel article, the Pentagon 1024 SL); pp. 454–456 (Scorpion).
- Sinclair User issue 49, April 1986, letters: a Brazilian TK 90X owner on the replaced ULA and on Elite and Tomahawk.
- Micro Sistemas (Brazil), special edition “Informática 85”, September 1985: the TK 90X, “lançado em junho”, and its specification. See Micro Sistemas.
- Ladislav Sieger, “Ještě jednou Didaktik Gama”, Mikrobáze (Czechoslovakia) no. 2, 1989: the launch before Christmas 1987, výrobní družstvo Služba Bratislava, závod Didaktik Skalica, the television advertisement, the compatibility problems, “taky nic jiného téměř není” (in Czech).
- Bajtek (Poland) 2/1988: the Elwro 800 Junior, “podstawowy komputer edukacyjny”, and the ministry’s purchases. Bajtek 3/1991: results of the 1989–90 survey of computers in Polish secondary schools (in Polish).
- John Szczepaniak, “Russia”, Retro Gamer issue 15, 2005, pp. 68–69: the Pentagon 128, Scorpion 256 and Kay 1024; Beta Disk on about 80 per cent of clones; the scene “still big”.
- Sinclair User issue 126, August 1992: the Hobbit feature (InterCompex, Dmitry Mikhilov, £79 and £59, InterCompex-ADB Russian Services). Issue 130, December 1992: “Hobbit to land at last”.
- TZX tape format specification, version 1.13, hardware type table. https://worldofspectrum.net/TZXformat.html
- For the Byte, the Radio-86RK and the background of Soviet home computing, see Soviet computing; for the TBBlue and the TK95, see ZX Spectrum Next and Brazil’s market reserve.