The Galaksija (; , 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.

History

In the early eighties, restrictions in SFR Yugoslavia prevented importing computers into the country. At the same time, even the cheapest computers available in the West were nearing average monthly salaries.

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.

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.

  • MIPRO and Elektronika from Buje, together with the Institute for Electronics and Vacuum Technology (Serbian: Institut za elektroniku i vakuumsku tehniku) delivered PCBs, keyboards and masks
  • Mikrotehnika from Graz sent integrated circuits
  • Voja Antonić personally programmed all EPROMs
  • Galaksija collected requisition forms and organized deliveries

Later, the Institute for School Books and Teaching Aids (Serbian: Zavod za udžbenike i nastavna sredstva), together with Elektronika Inženjering, started mass commercial production of Galaksija computers, mainly to be delivered to schools.

Technical specifications

  • CPU: Zilog Z80A 3.072 MHz
  • ROM "A" or "1" – 4 KB (2732 EPROM) contains bootstrap, core control and Galaksija BASIC interpreter code
  • ROM "B" or "2" – 4 KB (optional, also 2732 EPROM) – additional Galaksija BASIC commands, assembler, machine code monitor, etc.
  • Character ROM – 2 KB (2716 EPROM) contains character definitions, characters are 8×13 pixels, the block graphics were vertically divided in a 4:5:4 scheme, and horizontally in a 4:4 scheme.
  • RAM: 2 to 6 KB of 6116 static RAM in base model, expandable to 54 KB
  • Text mode 32 x 16 characters, monochrome
  • Pseudographics: 2×3 dot matrix combinations in graphic character subset – 64 distinct patterns in total
  • Sound: None according to specifications, but tape interface was occasionally used as audio output port – like the "EAR" port on ZX Spectrum can be used both as audio and cassette tape interface. See cassette port for details.
  • Storage media: cassette tape, recording at 280 bit/s rate
  • I/O ports: 44-pin edge connector with Z80 Bus, tape (DIN connector), monochrome video out (PAL timings, DIN connector), and UHF TV out (RCA connector)

BASIC ROMs

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.

  • Codepoints 91 to 94 (0x5B to 0x5E) represent the Serbian characters Č, Ć, Ž and Š, respectively.

Each character is represented as a 8×16 matrix of pixels. In this ROM, 8-pixel rows of each character are represented as 8 bits of one byte.

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"Cassette" port

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.

Software sharing via radio

In Autumn 1983, Računari's editor contacted Zoran Modli, the DJ of Radio Belgrade 202's Ventilator 202 program, asking him to broadcast software as part of the show.

Design

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 component-side connections to be made using wire links.

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 wire links.

<gallery mode="packed">

File:Galaksija 1984.jpg|Galaksija's mainboard, partly assembled

File:Galaksija Ready Prompt.png|Ready prompt at startup

File:Desktop computer GALAKSIJA, 1983.jpg|Later factory-manufactured Galaksija case

File:Galaksija home computer.jpg|A Galaksija at BalCCon2k14 Novi Sad, Serbia

File:Voja Antonic.jpg|Voja Antonic, inventor of the Galaksija

</gallery>

See also

  • History of computer hardware in Yugoslavia
  • Galaksija BASIC – details about Galaksija's BASIC programming language
  • Galaksija Plus – improved version of Galaksija, announced in Jun/July 1984 (6th) issue of "Računari" magazine (in English: Computers, renamed from "Računari u vašoj kući")
  • Voja Antonić – the creator of Galaksija
  • Dejan Ristanović – well known Serbian writer and computer publicist who authored much of the special issue magazine featuring Galaksija
  • Z80 – Galaksija's CPU
  • ZX80 – Sinclair ZX80 which predates the Galaksija by 4 years and has a remarkably similar system design including using the Z80A to drive the video output.

References

Articles

  • Computers in your home – short overview by Dejan Ristanović, the author of Računari u vašoj kući magazine issue (in English)
  • 1983: Galaksija – how it all started, by Galaksija's creator Voja Antonić himself (in Serbian)
  • Computer Galaksija – detailed description of computer operation for those planning to build it, as published in the Računari u vašoj kući magazine issue. Written by creator Voja Antonić (in Serbian).
  • Uputstvo za upotrebu – complete, original, user manual on-line (in Serbian)
  • Magazine Scans – scans of original magazine pages containing schematic diagrams, building and other instructions and programs for Galaksija (in Serbian)
  • Računar Galaksija by Dejan Ristanović, the author of Računari u vašoj kući magazine issue (in Serbian)
  • Crowd Supply Project - Crowd Supply Project may offer another Galaksija

Presentations

  • The Ultimate Galaksija Talk - in-depth presentation by Tomaž Šolc given at the 29C3 conference

Remakes

  • μGalaksija – FPGA Galaksija
  • CMOS – CMOS Galaksija

Emulators

  • Galaksija Emulator – original DOS-based emulator by Miodrag Jevremović (in Serbian)
  • Galaksija Emulator pages – Microsoft Windows port of original DOS emulator (in Serbian)
  • MESS – The open source multi-platform multi-system emulator MESS supports Galaksija
  • SimCoupe – A Galaksija emulator running under SAM Coupé
  • GALe – Galaksija Emulator – Emulates Galaksija in web browser

Online museums

  • Old-Computers.com Museum page on Galaksija
  • Zgodovina – an article in Slovene

Other

  • Zoran Modli Home page home page of Ventilator 202 radio show host (in Serbian). Same site contains a story of Ventilator 202 show, (also in Serbian).
  • #247 – An Interview with Voja Antonic – Gerontogenous Galaksija Genesis An audio podcast interview with Voja Antonic about the creation of the Galaksija, in English.
  • galaksija info in English with reproduced schematics, and an English translation of the thesis document "about the CMOS implementation of the GALAKSIJA retro home build computer"