The Cold War was responsible for producing two things over the run of its 44-year course- fear and technology. While the fear eventually faded away, the surplus of technology remained, and a lot of it can be found up for sale on sites such as eBay for cheap, which makes for great projects- including those that incorporate Nixie tubes.
For his 11th grade history project, Alex Studer drew inspiration from Alexey Pajitnov’s Tetris and decided he wanted to recreate an 80’s era Soviet Microcomputer, or at least approximate one anyway. After giving some thought, Struder based his computer design around a U880 — an East German clone of the Zilog Z80 8-bit microprocessor, outfitted with 8Kb of ROM, and 4Kb of RAM.
For input and output, Struder opted to go for modern day equivalents to old Soviet chips, with an Intel 8251A (replacing a KR580VV51A) that acts as a Serial port, and an Intel 8255A (replacing a KR580VV55A) for button inputs. To handle decoding logic without jamming up the data bus, Struder went with an East German-manufactured V4028 coupled with a Soviet K155LN1 (hex inverter) chip.
Piping video to an old CRT just wouldn’t cut it, certainly in the portability area, so a 128 x 64 LCD display was incorporated into the project, along with several buffer chips (2X for addressing lines, 1X for data), to keep things copacetic. Struder designed his system using KiCAD, using the platform’s symbology to replace the Russian equivalents and had to tweak some of the pin spacing to get the hardware to fit neatly.
Programming was done using an assembler Struder wrote for the GameBoy and adapted it into the z80asm language for the Z80 microprocessor. He also created an emulator (with a simple debugger) for the platform, which allows him to play a great version of Tetris on the tiny display. Struder has linked all of the schematics and code on his project page for those looking to build their own version of his Soviet-era Microcomputer.