Радио 86РК (Radio 86RK): Part 1 (Modern Homebrew Build) [TCE

Thanks to #PCBWAY for helping make this project possible!
The Radio 86RK was an early Soviet home brew computer (not the first) designed around their version of the Intel 8080, the КР580ВМ80А. It is named after the magazine it was featured in, РАДИО (or RADIO), with the РК (or RK) standing for "Радио Компьютер" (or radio computer), indicating that it was targeted at ham radio enthusiasts, similar to the use of a "ham shack" computer in the West.
It was then used as the basis for a range of industrially produced computers, such as the Партнер 01.01 (Partner) and Альфа БК (Alpha BK) already featured on this channel, which provided a case & keyboard, as well as saving the builder from trying to source scarce parts on their own.
This isn't an original build but Sergey Kiselev's updated version - I'm using v1.3 of his board which requires 2716 (2KByte) EPROMs still and uses the quirky JCUKEN keyboard layout. He has created a v1.4 that allows larger/newer EPROMs to be used as well as switching to the more familiar QWERTY keyboard layout.
github.com/skiselev/radio-86rk
Getting a hold of the parts wasn't too difficult - I sourced the older ones from Unicorn Electronics in the US (as suggested by Sergey).
unicornelectronics.com/
The problem with 2716 EPROMs is not sourcing them but finding a programmer that can program them - I'm using the AR-32A from Andromeda Research Labs along with my Book 8088.
www.arlabs.com/eprom_plus.html
Shout out also to Adam (‪@adamradipat1715‬) for sending me both a Polish and a Soviet 8080! As I progress with this machine, I'll try to swap out as many of the Western parts for more authentic Eastern Bloc parts as I can.
Planning to try loading ROM and cassette software in the following videos.

[@deepmaze1]

All my childhood I dreamed about this PC cause it was the most famous home brew PC in USSR. It was a virtual Raspberry Pi of its time but.....if you wanted to make some then you had to commit a crime of stealing very rare MCs from the military oriented factories. That is why commoners had only БК, ПОИСК (this one was for cool kids with parents in the Party HQ), Вектор and later on we had all kinds of ZX Spectrum clones. By commoners I mean families with the elite jobs like plane pilots, high ranked scientists, ruling system members and crime lords of the era. You could easily swap any PC for a motorcycle or two PCs for a ВАЗ 2101 car in late 1980 - early 1990. Real Western IBM PC desktop machine could be a reason why your apartment has the same security as the police armory and why you could be stabbed and looted at the streets if you had 5inch floppies (not because bandits had PCs but because floppies were a part of the USSR's cargo cult.).
Радио-86РК disappeared from the market in 1991......
Complete HP 486 DX2 66Mhz (VGA 15'' monitor, 32RAM, 1Mb VESA Video, 200+mb HDD, no CD ROM, no Sound card, no modem) in 1994 was exactly 2440real money and no sales for local money were possible cause it would be too much paper weight.
Cheapest 386SX 200 based system with 2MB of ram and 40Mb HDD was 1200
Compaq 80286 based system with 1.2Mb of ram and 20mb hdd was no less than 800
ZX clone of the same era was around 200 real money with a color monitor while motorcycle was around 30.
In 1995 Pentuim appeared and all the Post USSR computer market gone mad. Everyone started to ditch everything older than 486. Prices were cut in half but still too expensive for students. The same year green capacitors looting became a thing. Science workers demolished old ДВК and Поиск based educational classes, mainframes, science equipment and TV station hardware in order to buy at least one 386. ZX 48 clones market flopped. ZX Scorpion based marked lived for three more years. By 1998 there were little to none old era USSR made mainframes and classes. I remember when punch cards were EVERYWHERE at the streets of my city cause software warehouses went to a dumpster and looting.
ZX and БК base game clubs went down last. it was way cheaper to use Nintendo systems ripoffs as a gaming clubs hardware.

[@arampak]

Cool, I was reading Radio magazine at the time and skipping over those pages because the schematic and the number of ICs were way over my head and my ability to obtain them.

[@PhobosTK]

Man this is cool

[@varjagg]

Heh I remember reading the series in the original magazine. Also the competing design Specialist/Специалист in another magazine around 1987, which I was subscribed to then. The latter turned even more obscure.

[@Brfff]

Oooo, I've not heard of that one ... interesting. I'll have to keep an eye out but I guess it might be hard/rare to find one
ru.wikipedia.org/wiki/Специалист_(компьютер)

[@varjagg]

@@Brfff There was even a rarer one, ЮТ-88. Also a magazine design, closer in concept to KIM-1 or other trainers. I'm not even sure these were industrialized in any way or just existed as homebrew builds.
en.wikipedia.org/wiki/UT-88

[@Toreonify]

I need to get an oscilloscope and fix my father's Радио-86РК that he built himself from the scratch. Keyboard was made with buttons from desk calculators if I recall correctly) He with his friend built several of those at work and one of them had a peculiar fault: EPROM would not work until a lightbulb was placed on top of the erase window.

[@JVHShack]

There is something with the combination of older ICs and turned pin sockets that sometimes make whatever computer or other device non-functional. Sometimes, the pins can work themselves out of the sockets. @Epictronics discovered this recently while working on a C64. Because of his discovery, he had to replace the turned-pin socket with a dual wipe one. He does a very good explanation as to why in his latest video.

[@viktoruzhgorod]

Particularly the 54LS series. I suspect this is because they have thinner legs.

[@Brfff]

I'm also (slightly) mixing 2.5mm and 2.54mm pitch as well ... just one of the EPROMs at the moment

[@viktoruzhgorod]

@@Brfff The pitch mismatch in this case makes connections actually better, so no worries, it really does not matter up to 28 pin count. 40pin ICs is where is gets annoying.

[@MrWaalkman]

Why not use a 28C16 as an alternative to the 27C16?
Nice to see it working!

[@Brfff]

Ahhh good point - it's not something that I've got handy, and I'm assuming they're easier to program ... don't require the high voltage that the 2716s require.

[@MrWaalkman]

@@Brfff Oh yeah, EEPROM - Electrically Erasable! Not in circuit of course... Or find a EPROM programmer that can handle the higher voltage of the 2716. Clearly they exist.

[@Brfff]

@@MrWaalkman Ahem, like the one I mentioned in the Video Description? :)

[@MrWaalkman]

​@@Brfff Yup, I saw that. And I remember that you mentioned it awhile back. And that it can handle the higher voltages. But I can't recall if we ever saw it in action.
But we would need a solution for the rest of us mere mortals. We all can't send our EPROMs to Oz to get them programmed... :)

[@viktoruzhgorod]

I can't see any misbehavior. So where is it misbehaving exactly? Although 61C for a 8080 seems way too high to me. It means it's impossible to hold a finger on it, and I never met an 8080 so hot.

[@Brfff]

Edited out ...
[1] On first power on with Polish 8080, nothing happened;
[2] With Western 8080, black screen;
[3] Then boots with flashing cursor;
[4] Get RADIO prompt then blank screen with flashing cursor;
[5] Get RADIO prompt, appears to be working then crashes after a minute;
[6] Get RADIO prompt, pressing any key reboots
Yes, I agree ... the 8080 seems to be running too hot ... but the Альфа БК is the same (see around 33:31 mark in Part 4 video [TCE #0458])

[@josefjelinek]

@@Brfff I think these should not have been edited out, they would make the journey more interesting IMHO.

[@Brfff]

​@@josefjelinek I'll add them back in for Part 2 (loading ROM software)

[@viktoruzhgorod]

Yeah, I've seen your struggles with the Alpha. Connect a keyboard (basically, the pull-ups that are necessary) and there you go. The unconnected keyboard on a radio 86 RK causes all sorts of weird issues, because the PPA is picking up unpredictable $hit. And the cyrillic characters are displayed, because the keyboard (and screen) layout is currently russian. Most probably that is the issue, at least worth a try...

[@archivis]

mnoo