Retrocomputing on a Chip

New electrical components enable us to reconstruct old wiring more efficiently. Especially, the accessible and cheap FPGA kits which offer the possibility to put together wiring of many old computers as an “on-a-chip” solution.

When I managed to get a hold of an old bubble LED display and a pretty mechanical matrix keyboard, I decided to build a replica of an old single board computer. Logical options seemed to be to build either KIM-1 or Heathkit ET-3400. Replicas of KIM-1 already exist, even for Arduino, so my task would be reduced to connect the keyboard and display. But then I told myself that I would use the fact that my bubble display has 9 positions as an excuse to build the legendary Czechoslovak Single Board Computer PMI-80 which used the same display. My replica is an FPGA, or rather an FPGA emulator of this very computer.

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Peripherals Behind The Iron Curtain

The article Home Computers Behind the Iron Curtain sparked a lot of interest, which made me very happy. Therefore, I decided to introduce more computer curiosities from the Iron Curtain period, especially from the former Czechoslovakia (CSSR).

As I mentioned in the previous article, the lack of spare parts, literature and technology in Czechoslovakia forced geeks to solve it themselves: by improvisation and what we would today call “hacking.”  Hobbyist projects of one person or a small party was eventually taken over by a state-owned enterprise, which then began to manufacture and deliver to stores with some minor modifications. These projects most often involved a variety of peripherals that could only be found in the Czechoslovakia with great difficulty.

Much like the production of components, the production of peripherals was also distributed throughout the eastern block so that each country was specializing in certain types of peripherals. For example, East Germany produced matrix printers, and Bulgaria made floppy disks drives. This meant industrial enterprises had to wait for vital computer parts, because the production in another country was not sufficient to cover even the local requirements, let alone the home user.

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Home Computers Behind The Iron Curtain

I was born in 1973 in Czechoslovakia. It was a small country in the middle of Europe, unfortunately on the dark side of the Iron Curtain. We had never been a part of Soviet Union (as many think), but we were so-called “Soviet Satellite”, side by side with Poland, Hungary, and East Germany.

My hobbies were electronics and – in the middle of 80s – computers. The history of computers behind the Iron Curtain is very interesting, with a lot of unusual moments. For example – communists at first called cybernetics as “bourgeois’ pseudoscience” (as well as sociology or semiotics), “used to enslave a mankind by machines”. But later on they understood the importance of computers, primarily for science and army. So in 50s the Eastern Bloc started to build its own computers, separately and “in its own way.”

The biggest problem was a lack of modern technologies. There were a lot of skilled and clever people in eastern countries, but they had a lot of problems with the elementary technical things. Manufacturing of electronics parts was divided into diverse countries of Comecon – The Council for Mutual Economic Assistance. In reality, it led to an absurd situation: You could buy the eastern copy of Z80 (made in Eastern Germany as U880D), but you couldn’t buy 74LS00 at the same time. Yes, a lot of manufacturers made it, but “it is out of stock now; try to ask next year”. So “make a computer” meant 50 percent of electronics skills and 50 percent of unofficial social network and knowledge like “I know a guy who knows a guy and his neighbor works in a factory, where they maybe have a material for PCBs” at those times.

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