In January 1984 a Belgrade magazine sold its readers a computer in the form of instructions. Računari u vašoj kući (“Computers in Your Home”), a 200-dinar special edition of the popular-science magazine Galaksija, promised on its cover “complete instructions for building a home computer yourself”. The machine inside was also called the Galaksija, and its editorial said it had been designed by “one man, Voja Antonić”.
Building your own computer in Yugoslavia was not a hobbyist’s affectation. Personal imports were restricted, foreign currency was hard to get, and Antonić’s build article warned that any single parcel of parts from abroad worth more than 1,500 dinars “will be returned and will never reach you”. The Galaksija was designed around that problem. It used a few common chips, and the magazine arranged for the parts that could not be bought at home. Its most unusual feature followed from the same economy: it had no video chip, so the Z80 processor drew the picture itself.
Fast facts
- Published: January 1984, in Računari u vašoj kući, a special edition of Galaksija, written by Dejan Ristanović.
- Designer: Voja Antonić.
- CPU: Zilog Z80A, from a 6.144 MHz crystal; the processor ran at 3.072 MHz.
- ROM: 4K in a 2732 EPROM (BASIC and the operating system), with room for a second 4K ROM; character patterns in a 2K 2716 EPROM.
- RAM: 2K 6116 chips on the board (the parts kit offered 4K or 6K), expandable to 48K through the rear connector.
- Display: 16 lines of 32 characters, and block graphics of 64×48; black and white, to a TV through an RF modulator or to a modified set as raw video.
- Keyboard: 54 keys.
- Storage: cassette, at 280 baud.
- Built: “nearly 6,000”, according to Svet kompjutera in October 1984.
A computer in a magazine
The special edition’s cover names its author as Dejan Ristanović. Its editorial described the Galaksija as the crowning of two years’ work popularising home computers in the pages of Galaksija. It sold the reader a set of instructions rather than a machine: Antonić’s build article, the schematic and board layout, and a guide to the BASIC.
The article is candid about how hard building a computer would be. “Some key parts of the computer, such as ROM, cannot be freely bought in any parts of the world, and others, such as the keyboard, can be found neither easily nor cheaply. In our country, where it’s hard to find even the most common resistor, getting into this adventure might seem insane.” The magazine’s answer was a network of suppliers:
| Part | Where it came from | Price |
|---|---|---|
| Circuit board, connector board, keyboard mask and keys | MIPRO and Elektronika of Buje, with keys from the Institute of Vacuum Technology in Ljubljana | 4,300 dinars, or 3,660 for the first hundred orders |
| Integrated circuits, RF modulator, crystal and sockets | Microtechnica of Graz, Austria, by mail order | 1,000 schillings (about 6,500 dinars) with 4K of RAM, 1,116 schillings with 6K |
| Programmed EPROMs | Free with the Microtechnica set, or programmed free of charge by MIPRO of Belgrade | postage |
The parts only came as a complete set. A footnote apologised: “Sorry Spectrum and ZX 81 owners!” Another explained that orders would be accepted only from 5 January, because the special edition did not reach every kiosk on the same day. Readers who got stuck could ring a help line run with the Avala amateur-radio club in Belgrade, which also offered free building courses. The article put the total, in the worst case with import duty, at no more than 15,500 dinars.
It also said what to do when things went wrong. A builder who saw nine small copies of the screen instead of one, the article explained, had a crystal oscillating at three times its proper 6.144 MHz, and needed to solder in a small capacitor.
How the Z80 draws the screen
Most home computers of 1984 had a chip whose job was to generate the television picture. The Galaksija left the job to its processor, as Sinclair’s ZX81 did. That kept the parts list short and cheap. The cost was processor time.
The ROM’s own assembly listing, headed “MALI RACUNAR ‘GALAKSIJA’ — VOJA ANTONIC — 03.01.1984”, shows how. The video driver is the Z80’s interrupt routine, at address 0038H, labelled INT VIDEO. It sets up the processor’s I register and its R register, the memory-refresh counter that a Z80 places on the address bus after fetching each instruction, and then runs a loop labelled LINIJE (“lines”) in which the timing of every instruction matters. In the surviving copy of the listing, someone has pencilled the clock-cycle count of each instruction in that loop into the margin. The same interrupt also keeps a clock, updating a time string at 2A80H.
Near the start of the ROM sit two routines of two bytes each. FAST is DI followed by RET: it disables interrupts, so the video routine stops running and the processor has all its time for the program. SLOW is EI, RET, which lets the picture back in. It is the same trade the ZX81 offered its users.
The picture was modest: 32 characters on each of 16 lines, and block graphics that divide each character cell into 2×3 blocks, giving 64×48 points. The special edition itself listed the low resolution among the machine’s drawbacks.
What happened next
The Galaksija caught on. In October 1984 Svet kompjutera called it “our most popular home computer”, with “nearly 6,000 machines” in Yugoslav homes. It said the kit could be bought through Galaksija for about 20,000 dinars, and a ready-built machine through the Institute for Textbooks and Teaching Aids (Zavod za udžbenike i nastavna sredstva) in Belgrade for about 40,000. Factory-built machines came from Elektronika inženjering, whose logo appeared on the screen at start-up.
Računari u vašoj kući became a magazine in its own right, Računari, and it and Svet kompjutera printed Galaksija programs, add-ons and explanations of its ROM for years afterwards. A second ROM added extra BASIC commands, an assembler and a machine-code monitor. An improved model, the Galaksija Plus, with 48K of RAM, high-resolution graphics and a sound generator, was reviewed in Računari in October 1985. Later accounts also describe Radio Belgrade’s Ventilator 202 broadcasting programs for the Galaksija and other computers, which listeners recorded straight onto cassette.
The design has outlived the country that produced it. The machine is emulated in MAME, runs as an FPGA core on the MiSTer, and is still built from the original instructions. Antonić later released a revised two-layer circuit board with modern key switches. It adds a capacitor on the Z80’s refresh line, because CMOS versions of the Z80 have slightly different timing and the Galaksija’s picture depends on that signal.
Sources
- Računari u vašoj kući, special edition of Galaksija, January 1984: cover (price, “kompletno uputstvo za samogradnju kućnog kompjutera”), editorial (two years of Galaksija’s coverage; “Računar ‘Galaksija’ je projektovao jedan jedini čovek, Voja Antonić”), specification (16 lines of 32 characters, 64×48 graphics, 280-baud cassette, 44-pin expansion connector) and the limited resolution.
- Voja Antonić, “The Galaksija Home Computer”, the build article from the January 1984 special edition, English translation by Travis Goodspeed and Aleks Nikolić in PoC||GTFO Volume 2 (No Starch Press, 2018), pp. 26–30 of the article: RF or raw video, the 6.144 MHz crystal, the parts suppliers and prices, the 1,500-dinar limit on imports, EPROM programming, order and delivery dates, and the Avala help line.
- Voja Antonić, Galaksija ROM A assembly listing, version 28, dated 3 January 1984: the
INT VIDEOinterrupt routine, theLINIJEloop, theFASTandSLOWroutines, the clock string and the NMI “hard break”. A scan is in the public mejs/galaksija archive on GitHub (web, secondary). https://github.com/mejs/galaksija - Svet kompjutera, October 1984: the cost of imported chips in foreign currency; “our most popular home computer”, nearly 6,000 machines, kit and assembled prices, and specifications (Z80A, 4K or 8K ROM, 2K RAM expandable to 48K, 54 keys, 64×48 points, 16 lines of 32 characters).
- Računari, October 1985: review of the Galaksija Plus.
- mejs/galaksija repository README (GitHub, accessed September 2026) (web, secondary): ROM B’s contents, the Elektronika inženjering and MIPRO character-ROM logos, and Antonić’s two-layer board with the capacitor on the refresh line. https://github.com/mejs/galaksija
- Wikipedia, “Galaksija (computer)” (accessed September 2026) (web, secondary): restrictions on importing computers, the 3.072 MHz processor clock, the 2×3 block graphics, Elektronika inženjering’s factory production, ROM B’s assembler and monitor, and the Ventilator 202 broadcasts, and MAME emulation. https://en.wikipedia.org/wiki/Galaksija_(computer)
- MiSTer-devel, Galaksija_MiSTer (GitHub, accessed September 2026) (web, secondary): the FPGA core. https://github.com/MiSTer-devel/Galaksija_MiSTer