Galaksija (computer)

The Galaksija (Serbian Cyrillic: Галаксија; [galǎksija], meaning "Galaxy") was 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 1984.jpg
Main board of Galaksija during assembly process
TypeHome computer
Release date1983; 39 years ago (1983)
MediaCompact Cassettes
CPUZilog Z80A @ 3.072 MHz
Memory2–6KB RAM, 4–8KB ROM
Display64x48 monochrome
SuccessorGalaksija Plus


In the early eighties, restrictions in SFR Yugoslavia prevented importing computers into the country.[1] At the same time, even the cheapest computers available in the West were nearing average monthly salaries.[1] This meant that only a relative minority of people owned one – mostly a ZX Spectrum or a Commodore 64, though most Yugoslavs were only familiar with a programmable calculator.[2]

According to his own words,[3] 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.[3] 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.[2] Although using software as opposed to hardware would significantly reduce his design's performance, it also simplified the hardware and reduced its cost.[4]

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.[3] Near the same time that Antonić made his discovery, Dejan Ristanović, a computer programmer and journalist was entrusted with preparing a special edition of the Galaksija magazine that would be focused on home computers.[1] After Ristanović and Antonić met, they decided to collaborate and publish the computer's diagram in a special issue of the magazine entitled Računari u vašoj kući (Computers in your home).[1] It was released late December 1983.[2] The name of the magazine (Galaksija) would become twinned with the name of the computer.[2]

Antonić and Ristanović guesstimated that around a thousand people would try to build the computer by themselves, given that the magazine's circulation was 30,000.[4] Some 8,000 people wound up ordering the build-it-yourself kits from Antonić.[4] This number may in reality be greater if people who did not purchase any kits (including PCB and ROMs) were accounted for.

Components were provided by various manufacturers and suppliers:[5]

Later, Institute for school books and teaching aids together with Elektronika Inženjering started mass commercial production of Galaksija computers, mainly to be delivered to schools.[6]

Technical specificationsEdit


Galaksija BASIC is a BASIC interpreter originally partly based on code taken from TRS-80 Level 1 BASIC, which the creator believed to have been a Microsoft BASIC.[3] However, after extensive modifications to include video generation code (as the CPU was a major participant to reduce the cost of hardware) and improve the programming language, what remained from the original is said to be mainly flow-control and floating point code. It was fully contained in 4 KB ROM "A" or "1". Additional ROM "B" or "2" provided more Galaksija BASIC commands, assembler, monitor, etc.

ROM "A"Edit

The chip labeled as "A" by the creator of Galaksija, Voja Antonić was commonly referred to as "ROM 1" or just "ROM". ROM "A" contained bootstrap code of Galaksija, its control code (rudimentary operating system), video generation code (as Galaksija did not have advanced video subsystem its Z80 CPU was responsible even for generating video signal) and Galaksija BASIC.

Fitting all this functionality in 4 KB of 2732 EPROM required a lot of effort and some sacrifices. For example, some message text areas were also used actual code (e.g. "READY" message) and the number of error messages was reduced to only three ("WHAT?", "HOW?" and "SORRY").[2]

ROM "B"Edit

ROM "B" of the Galaksija is a 2732 EPROM chip that contains extensions to the original Galaksija BASIC available in base ROM ("A"). It was labeled as "B" by the creator of the Galaksija, Voja Antonić, but was commonly referred to as "ROM 2".

ROM "B" contained added Galaksija BASIC commands and functions (mostly trigonometric) as well as a Z80 assembler and a machine code monitor. This ROM was not required and was an optional upgrade. Although planned on the mainboard, the content of ROM "B" was not automatically initialized during booting. Instead, users had to execute a Galaksija BASIC command to run a machine code program from ROM "B" before they can gain additional features. This also meant that even Galaksijas with ROM "B" plugged in can behave entirely as base models.

Character ROMEdit

Character ROM of home computer Galaksija is a 2716 EPROM chip that contains graphical definitions of Galaksija's character set. It had no special name and was labeled "2716" after the type of 2 KB EPROM needed.

Galaksija had a slightly modified (localized) ASCII character set:

  • There were no lowercase characters
  • Codes 91 to 94 represented the Serbian characters Č, Ć, Ž and Š, respectively. The letter "Đ" was not present in original version and was commonly replaced with "DJ".
  • It contained 64 pseudo-graphics characters, having different combinations of dots in 2x3 matrix.
  • Character codes 64 and 39 are used for two-halves of the logo of Elektronika Inženjering company (they can be seen in "READY" prompt)

Each character was represented as 8x13 matrix of pixels. In this ROM, 8-pixel rows of each character are represented as 8 bits of one byte.

"Cassette" portEdit

Galaksija used cassette tape as secondary storage. It featured a 5-pin DIN connector used to connect the computer to a cassette tape recorder. Tape interface circuitry was rudimentary – other than few elements controlling the levels it was essentially one-bit digital equivalent to the one in the ZX Spectrum. The input signal was routed to the integrated circuit otherwise responsible for keyboard, so the CPU would "see" the input signal as a series of very fast key presses of varying lengths and gaps between them.

It is normally stated that original Galaksija does not have any dedicated (separate) audio ports and most of the programs were written as silent. It was, however, possible to utilize the cassette tape port as an audio output as well like it is done in ZX Spectrum (its "EAR" connector). The only technical difference between ZX Spectrum and Galaksija in regards to existence of audio is that ZX Spectrum has a built-in beeper, while Galaksija's plans do not include any kind of a speaker.


To simplify "do-it-yourself" building and reduce cost, the printed circuit board was designed as single-layer (one-side) board. This resulted in a relatively complicated design requiring many components-side connections to be made using wires.

Galaksija's case was not pre-built. Instead, the guide suggested it to be built out of the printed circuit board material (such as Pertinax) also used for the mainboard. Thus, the top, sides and reinforcements were soldered together to form the "lid". Acrylic glass was recommended for the underside. The guide included instructions on cleaning, painting and even decorating the assembled case. The name "GALAKSIJA" and decorative border were to be added using Letraset transfer letter sheets after the first (white) coat of paint but before the second coat of final colour. After the paint dried, transferred decorations were supposed to be scratched off, exposing underlying white paint.

The keyboard is laid out such that keys have their own memory-mapped addresses that, in most cases, follow the same order as ASCII code of the letter on the key. This saved the ROM space by reducing lookup tables but significantly increased the complexity of single-layer keyboard PCB such that it alone required 35 jumpers.


See alsoEdit


  1. ^ a b c d Eby, Michael (8 February 2020). "The Lost History of Socialism's DIY Computer". Jacobin Magazine.
  2. ^ a b c d e Packwood, Lewis (30 July 2013). "The story of Yugoslavia's DIY computer revolution".
  3. ^ a b c d Antonić, Voja. "1983: Galaksija". Archived from the original on 4 May 2009. Retrieved 17 June 2010.
  4. ^ a b c Alberts, Gerard; Oldenziel, Ruth (2014). Hacking Europe: From Computer Cultures to Demoscenes. Springer. pp. 119–121. ISBN 978-1-44715-493-8.
  5. ^ Laphroaig, Manul (2018). PoC or GTFO, Volume 2. No Starch Press. pp. 98–100. ISBN 978-1-59327-935-6.
  6. ^ "Priča o Galaksiji" [The story of the Galaksija].

External linksEdit





Online museumsEdit