When [Kasyan] was six years old, he saw a RADUGA computer, a Russian unit from the 1990s, and it sparked his imagination. He has one now that is a little beat up, but we feel like he sees it through his six-year-old eyes as a shiny new computer. The computer, which you can see in the video below, was a clone of the Spectrum 48K.
The box is somewhat klunky-looking, and inside is also a bit strange. The power supply is a — for the time — state-of-the-art switching power supply. Since it wasn’t in good shape, he decided to replace it with a more modern supply.
The main board was also not in good shape. A Zilog CPU is on a large PCB with suspicious-looking capacitors. The mechanical keyboard is nothing more than a array of buttons, and wouldn’t excite today’s mechanical key enthusiast.
The computer isn’t working yet. [Kasyan] is looking for someone who has the exact schematic, although he’s found a similar one and identified at least some of the problems on the board.
The USSR did a lot of work with early computing, but we don’t hear as much about it. That’s surprising, as they had a very active home computer scene.
Wonderful machine! 😃💙
These computer designs have something retro futuristic to them, I think.
The only thing I don’t really understand why they did bother to support color.
I mean, IBM’s CGA and the ZX Spectrum both look most eyefriendly in their hi-res modes and in monochrome.
Schematic is here: https://hww.github.io/rainbow_computer/storyboard/
I love things like this about Iron Curtain computers, we don’t hear much about them but they are fascinating.
Everyone who was in to diy electronics at that time and place(s), everyone was making “Speccy” clones. Including me. From simple 48K ones with RGB+sync output (we were hacking in to a middle of schematics of soviet color TVs for that) to 128K versions, multi-boot eeproms, floppy disc drives and AY sound chips.
During late 1980 and early 1990 there was a crazy demand for home computers in the Soviet Union:
Earlier in 1980’s a few DIY designs were published – starting with Micro-80 (“Radio” magazine, 1983), Radio-86RK (“Radio” magazine, 1986), Specialist (“Modelist-Constructor” magazine, 1987), UT-88 (“Junior technician” magazine supplement “for crafty hands” or something like that, 1988). All of these computers were based on a soviet 8080 clone – KR580VM80A CPU.
Industry also started to catch up, and manufactured a few computers roughly based on Radio-86RK design, as well as Electronika BK-0010 computer, which had a PDP-11 compatible CPUs. The main disadvantage of all these computers was pretty simple – they lacked software, most importantly – games. So it wasn’t long that a few people figured how to clone ZX Spectrum, partially implementing the ULA functionality using discrete logic, and hacking the firmware (BASIC) and the games to work with the modified hardware. Several such ZX Spectrum derived designs appeared, and there assembled by amateurs who could find the components, and eventually by cooperatives, small businesses, and even large defense industry factories.
The “home computer scene”, you’re referring to basically contained of the systems listed above, with perhaps some lucky individuals having MSX-compatible computers (imported to Russia’s far east mostly from Japan), PC compatibles (a few computer models were manufactured in the Soviet Union, although later mostly imported). The article you’ve linked describes computers from other eastern bloc countries. These designs were not known or popular in the Soviet Union…
Hi! This is both fascinating and sad same time.
But why the KR580VM80A and not the U880?
The i8080 was poorer than Z80 and was never meant to be in first place.
The “fathers” of the i8080 had left intel in order to found Zilog and fix the i8080 design.
The result was the Z80, the finished processor that the i8080 was meant to be.
PS: Why ZX Spectrum and not ZX81?
ZX81 was fun and the simple graphics didn’t hurt the eyes.
In late 1970’s Soviets made a decision to clone Intel 8xxx series. To avoid extra effort, they didn’t clone Z80, 6502, MC6800, MC68000, etc. at that time. Therefore KR580VM80 – the 8080 clone was relatively available. Soviets also manufactured 8086 and later 8088 clones.
The U880 was an East German design. It wasn’t commonly available in the Soviet Union. Later in early 90’s Soviets did make their own Z80 clone – KR1858VM1, mostly to satisfy the demand for ZX Spectrum clones (according to some, early KR1858VM1 used U880 die, but at least ones that I tested don’t behave like U880).
P.S. You’re correct that Intel 8080 and Zilog Z80 were designed by the same people. But I don’t think the Z80 “fixes” the 8080. It is rather a development of the 8080. Advances in the chip manufacturing process allowed Z80 to use single 5V power supply, implementing more registers and institutions, and integrating the clock generator and the bus controller (Z80 has almost twice more transistors than 8080)