Galaksija 1983 lowcost computer in Yugoslavia

In the early eighties, various laws in Yugoslavia prevented importing computers into the country. At the same time, even the cheapest computers available in the West were nearing average monthly salaries. This meant that regardless of demand for home computers, only a relative minority of people owned one – mostly a ZX Spectrum or a Commodore 64.

According to his own words, some time in 1983, Voja Antonić, while vacationing in Hotel Teuta in Risan, was reading the application handbook for the RCA CDP1802 CPU and stumbled upon CPU-assisted video generation. Since the CDP1802 was very primitive, he decided that a Zilog Z80 processor could perform the task as well.

Before he returned home to Belgrade, he already had the conceptual diagrams of a computer that used software to generate a video picture. Although using software as opposed to hardware would significantly reduce his design’s performance, it also simplified the hardware and reduced its cost.

His next step was to find a magazine to publish the diagrams in. The obvious choice was SAM Magazine published in Zagreb, but due to prior bad experiences he decided to publish elsewhere.


The Galaksija (pronounced Galaxiya Serbo-Croatian: meaning Galaxy) was originally a build-it-yourself computer designed by Voja Antonić. It was featured in the special edition Računari u vašoj kući(Computers in your home, written by Dejan Ristanović) of a popular eponymous science magazine, published late December 1983 in Belgrade, Yugoslavia. Kits were available but not required as it could be built entirely out of standard off-the-shelf parts. It was later also available in complete form.


Galaksija was almost not comparable by any measure of features to the commercially available computers at the time. However, that was not important. The computer sparked the minds of many people. Many enthusiasts have learned how computers actually work by looking at Galaksija’s schematic diagrams and Voja’s great descriptions. It was a great learning tool. Making a computer yourself boosts confidence and brings on the challenges of making the best out of it.

The Galaksija computer’s popularity was significant enough that it became commercially available. Many educational institutions were given some. Although many of them were not ready for the experience, many others used it as a great tool to teach computer science (computer architecture and programming) even in elementary schools (in 1984!). (from Wikipedia)

Galaksija was to be in Yugoslavia what Commodore and Sinclair were in the west. Whether it succeeded or not, its deceptively simple design can still teach us a lot of interesting tricks on how to make a usable computer and operating system with as few transistors and bits as possible.

Galaksija was a Yugoslavian home microcomputer popular in the local DIY community throughout the 1980s. It was meant as an alternative to illegally bought contemporary Sinclair and Commodore computers. It is a fascinating product of the time of severely limited availability of electronic components and a widespread disregard for copyright.

This situation led to unique design decisions on both the hardware and software side. Galaksija can display better graphics than Sinclair ZX 80 with only a small number of general-purpose digital logic integrated circuits. Since it included no specialized chips it was easy to build at home. Being constrained to a relatively small EPROM, Galaksija’s built-in BASIC interpreter was based on a stripped-down and hand-optimised Tandy TRS-80 ROM. It relies on undocumented Z80 features, “racing the beam”, executing error messages and floating point constants as code and similar tricks. By not including an auto-run feature the authors also made sure that Galaksija programs were hard to copy-protect, encouraging sharing and an early open-source like approach to developing software.

This is a talk inspired by the Atari 2600 and Commodore 64 ultimate talks from the previous Congresses and the 30th anniversary of Galaksija’s design. In 45 minutes it will include a brief introduction about the history of Galaksija and home microcomputers in Yugoslavia at the time. It will then cover all aspects of Galaksija’s hardware design, built-in ROM routines and original software that has been preserved to this day. It will end with coverage of what tools exist today to develop software for Galaksija, either for running in one of the software emulators, on hardware replicas or the real thing.

I’m an electronic engineer and this talk is based on my university diploma thesis about reverse engineering Galaksija’s hardware and software design and tracing back its origins. I have designed and made a working replica using modern CMOS logic that preserves Galaksija’s features, look and DIY-nature as much as possible. CMOS Galaksija has been presented in a number of retro-computing events and talks. I am also the author of a number of Galaksija demos and a Free software Galaksija developer’s kit.

Speaker: Tomaž Šolc
EventID: 5178
Event: 29th Chaos Communication Congress (29c3) by the Chaos Computer Club [CCC]
Location: Congress Centrum Hamburg (CCH); Am Dammtor; Marseiller Straße; 20355 Hamburg; Germany
Language: english

Dancing Demon is a game for TRS-80 model I written in 1979 by Leo Christopherson. Galaksija is a Yugoslavian home microcomputer from 1984 which uses a similar operating system and has similar hardware capabilities.

This video shows a modified Dancing Demon program running on Galaksija. Only animation routines will fit into Galaksija’s 6 kB of RAM, so this port doesn’t include an editor and doesn’t play a melody.

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