The Galaksija (Serbian Cyrillic: Галаксија; Serbian pronunciation: [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.
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. 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. 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. 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. 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). It was released late December 1983. The name of the magazine (Galaksija) would become twinned with the name of the computer. 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. Some 8,000 people wound up ordering the build-it-yourself kits from Antonić. 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:
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. 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" 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").
ROM "B" 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 ROM
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