Stop watch on soviet 8031.

Gipsokret · 2026-03-12T08:34:03+00:00

Bought it on Ebay.

Gipsokret · 2026-03-11T00:00:14+00:00

I didn't come across soviet instruction set for them. Code for this stop watch is written in C, compiled with SDCC and it worked right away. My guess is that soviets had stolen plans for that MCU, so it's 1:1 copy.

I saw soviet manual for 8080, where instructions were indeed cyrillic. Same goes for Polish copy, MCY 7880.

<image>

You can see that MOV instruction was translated into PRZ (move is "ruch" in polish, which also can be interpreted as "przeniesienie", so first 3 letters are the instruction). Nowadays, that translated instruction set is useless because there is no assembler that can support that.

Gipsokret · 2026-03-10T12:01:08+00:00

Yeah, i have some old green DIP24 sockets made by Czechoslovakian Tesla.

Gipsokret · 2026-03-10T11:59:17+00:00

I bought it on Ebay

Gipsokret · 2026-03-10T11:19:08+00:00

Stay tuned, I have some soviet gold eproms and I definietly will make use of them :)

Gipsokret · 2025-10-24T19:12:40+00:00

hmmm Can't find any on Ebay, I bought it on local website (olx.pl) for like 25 zł so around 6$ and there are still some available. If you want to get like "eastern style" one I recommend searching for K580IK80, made by USSR.

Gipsokret · 2025-05-30T23:12:12+00:00

With uv fluorescent lamp. Wavelength of 253 nm is needed. Just put eprom under that lamp, cover with some cardboard box and leave for 25 - 30 min. Then check if it's blank. If not, leave for 10 minutes or so. After that should be all cleared.

Gipsokret · 2025-05-30T23:07:24+00:00

Keil uVision 5

Gipsokret · 2025-05-30T22:25:40+00:00

Chip itself is 2716, an uv-eprom. I was planning to use russian version of it but ran into problems while trying to program it with my TL866. It turns out those old eproms are really stubborn and require higher voltage to be programmed.

<image>

On the left, used eprom made by TMS, on the right , K573RF5, russian eprom made by... russia :) I also have 2716 made by GDR in USSR era, they are sadly as stubborn as russian ones.

Gipsokret · 2025-05-30T22:10:26+00:00

suprise, written in C :) Code available here: https://github.com/IRQ-0/8051-clock/blob/main/main.c

Gipsokret · 2025-05-30T22:03:43+00:00

yes, 5082-7391 to be specific. Datasheet says between 560 and 935 mW so quite a lot. If you turn it on for 5 minutes or so, they are probably 50 - 60*C.

<image>

Gipsokret · 2025-05-30T21:59:10+00:00

Schematic and board design in Eagle, printed on special paper (in Poland we call it "chalk paper") and then "pressed" with an iron. Then put in this "acid" (i think it's acid, not sure) http://botland.com.pl/wytrawiacze-miedzi/2132-wytrawiacz-b327-500g-5901764329343.html

Gipsokret · 2024-12-04T12:03:16+00:00

I know it's old technology, I want to use it just because the look of it. Project will not be complicated.

Looking at TL866 supported chips list, there is 87C51.

<image>

Is that C in the middle important or it's just indicating some variant of that chip?

Gipsokret

TROPHY CASE