Building Galaksija, 40 years later

Galaksija (Galaxy) is a single-board Z80 computer, constructed in the early 1980s in Yugoslavia by Voja Antonić. It was publicly announced as a DIY project in the magazine Računari u vašoj kući (Computers in Your Home) in January 1984, complete with schematics and building instructions. There are countless blog posts, forum threads, magazine articles, and videos about this computer and its influence on the computer scene in socialist Yugoslavia (there is even a nice documentary movie released this year).

This year marks 40 years since the original announcement of Galaksija, and the magazine PC Press, together with the computer’s creator Voja Antonić, released an updated version of the computer. In this version, some of the ICs have been replaced with newer models (though the CPU remained the same), and the cassette tape interface was replaced with an EEPROM + UART combination. However, Galaksija essentially remains the same computer—still very simple to build and understand.

I didn’t want to miss this anniversary, so I bought the kit from PC Press. The kit includes a PCB, 2 ROMs (one for the operating system and another for the font), and acrylic back and front plates.

All other components (CPU and other ICs, resistors, capacitors, etc.) are available in another kit sold by a local electronics shop, but I decided to use components I already had and only buy what I was missing. This proved to be a bit challenging because I had to carefully compare specifications when I couldn’t find an exact match (on the other hand, this made the building process more interesting, and I learned new things along the way).

Building Galaksija shouldn’t be hard even for beginners in soldering. However, knowing about soldering in theory and actually doing it are completely different things. I am not new to soldering, but I don’t use my soldering iron more than a few times a year. Building Galaksija turned out to be great practice for my soldering skills, and I believe it would be appropriate even for complete beginners (provided they have someone more experienced to supervise them).

The only thing that was hard was soldering the SMD EEPROM. This was my first SMD soldering job, and it took me a few tries to get it right (well, good enough).

Galaksija outputs a video signal to an RCA connector (the big yellow thing in the following picture). To my surprise, Galaksija worked the first time I connected it to my smart TV. I didn’t even have to adjust any resistors to get a better picture - it is something that is often needed with builds like this (possibly because it was connected directly and not through an HDMI converter - can you believe they still make TVs with RCA?).

Along with the PCB kit, PC Press sells a booklet containing the restored original issue of the magazine with additional materials (over 150 pages in total). I didn’t buy it because it seemed a little pricey, and I knew the majority of the included material could be found online. However, after taking a look at a friend’s copy, I now think it’s definitely worth the money (if you’re the kind of person who likes to keep magazines).

Galaksija was never a computer designed to do а real work. Even in the 1980s when it was produced, it couldn’t compete with units from the Western market. But it was a great device for learning about computers - simple and affordable. Forty years later, in a time of unimaginable hardware and software complexity, it’s simplicity still makes it a great learning device. You can understand every part part of it - every resistor, every capacitor, every IC. Of course, now it is even more affordable (mine cost me around 100€ but you can get it cheeper if you have access to EEPROM programmer and you fab the PCB), which frees you from fear of making mistakes.

As for my learning path, the next step will be to build a simple compiler for Galaksija (still not sure if it will be BASIC or a custom language).