Information about the Soviet Ukrainian computer based on the Soviet homebrew computer called the РАДИО-86РК (RADIO-86RK). I'll refer to it as the "RK" (Radio Computer) for the rest of this description. This computer utilised the Soviet equivalent of the Intel 8080A called the КР580ВМ80А.
УМПК-Р = Универсальный МикроПроцессорный Комплект - Радио (Universal MicroProcessor Kit - Radio)
My computer doesn't work so I need to troubleshoot, hence this translation work. The Soviets were very good in including schematics & documentation how the computer works.
There were quite a few industrially produced clones of the RK design so understanding how it works can help with troubleshooting other machines.
- Part 1: First Look
- Part 2: Trying to get video output
- Part 3: Video output troubleshooting continues
- Part 4: Faulty DRAM?
- Part 5: Progress, Maybe
- Part 6: Quick Troubleshooting Update
- Part 7: New Keyboard
I have done a partial translation (thanks to Grok) of the Operation Manual - original scanned Russian, my cleaned-up Russian and the translated English manuals can be found here. There are four file types:
- Apple Pages (native)
- Rich Text Format
- MS Word
Note that there may be errors in my cleaned-up Russian copy ... some words in the scanned manual disappeared into the page binding!
Question: what on earth is "foiled lavsan" (фольгированный лавсан)?
"Lavsan" is a Russian trade name for a type of polyester film, chemically known as polyethylene terephthalate (PET). It is similar to materials like Mylar in Western terminology. "Фольгированный" means "foiled" or "coated with foil," indicating that the lavsan film has a thin layer of metal foil (often aluminium) applied to it. In the context of the УМПК-Р keyboard device, this refers to a metallised polyester film used in the membrane keyboard construction, where the foil provides conductive tracks or contacts for key operation.
So, in technical terms, it could be described as "metallised polyester film" or simply "foiled PET film", depending on the context.
In the English translation I have kept the Soviet/Russian part identifiers rather than transliterate them, but I have included Western equivalent part identifiers as well.
The scanned Russian manual includes the tables & diagrams referred to in the translation. It also includes a map of the parts on the motherboard.
I have also included some very-roughly machine translated (Google image) pages from the original Soviet RADIO magazine that explain the RK's functionality - I hope to come back and do better translations.
Due to the complete lack of 14-pin 32kbit DRAMs in the West I have replaced my faulty ones with 4164 64kbit DRAMs.
- D1 КР580ГФ24 8224 Clock generator
- D2 КР580ВТ57 8257 DMA controller
- D3 К155ИЕ4 74LS92 Divide-by-12 counter
- D4 К155ЛИ1 74LS08 Quad 2IN AND
- D5 КР580ВМ80А 8080A CPU
- D6 К155ЛП5 74LS86 Quad 2IN XOR
- D7 К589ИР12 8212 8-bit I/O port
- D8 КР580ВГ75 8275 CRT controller
- D9 К555ИД7 74LS138 1-of-8 decoder/demultiplexer
- D10 К155ЛА8 74LS01 Quad 2IN NAND
- D11 К155ЛН1 74LS04 Hex inverter
- D12 К573РФ2 2716 EPROM (for character data)
- D13 К155ТМ2 74LS74 Dual D-type flip flop
- D14 КР580ВВ55А 8255 Programmable peripheral adaptor
- D15 К155ИР1 74LS95 4-bit shift register
- D16 К155ИР13 74LS198 8-bit shift register
- D17 К555КП11 74LS257 Quad 2IN multiplexer
- D18 К555КП11 74LS257 Quad 2IN multiplexer
- D19 К573РФ5 2716 EPROM (for MONITOR)
- D20 КР565РУ5Д1 32K x 1bit DRAM
- D21 КР565РУ5Д1 32K x 1bit DRAM
- D22 КР565РУ5Д1 32K x 1bit DRAM
- D23 КР565РУ5Д1 32K x 1bit DRAM
- D24 КР580ВВ55А 8255 Programmable peripheral adaptor
- D25 КР565РУ5Д1 32K x 1bit DRAM
- D26 КР565РУ5Д1 32K x 1bit DRAM
- D27 КР565РУ5Д1 32K x 1bit DRAM
- D28 КР565РУ5Д1 32K x 1bit DRAM
- D29 К553УД2 LM301 Op. Amp.
I suspect that after 40-odd years (mid-1980s to mid-2020s) that the "foiled lavsan" membrane keyboard has started to malfunction. To replace it I have designed a new board using Cherry MX keyswitches. You will need to recover the СНП58-32 connector and the speaker from the original keyboard PCB, otherwise it uses readily available parts.
My initial design doesn't re-use the black, clip-on fascia - it expects you to have just the plain, naked PCB ... that's my preference. But I guess it would be good to design one for the fascia as well ...
24-Mar-2025: Submitted to PCBWAY for fabrication 20-Apr-2025: Built first board, mostly okay, some revisions required
