 Main board of Galaksija during assembly process | |
| Type | Home computer |
|---|---|
| Release date | 1983; 42 years ago (1983) |
| Media | Compact Cassettes |
| Operating system | Galaksija BASIC |
| CPU | Zilog Z80A @ 3.072 MHz |
| Memory | 2–6KBRAM, 4–8KBROM |
| Display | 32x16 text. 64x48 block graphics. monochrome |
| Input | Keyboard |
| Successor | Galaksija Plus |
TheGalaksija (Serbian Cyrillic:Галаксија;Serbian pronunciation:[galǎksija], meaning "Galaxy") was a build-it-yourself computer designed byVoja Antonić. It was featured in the special editionRačunari u vašoj kući (Computers in your home, written byDejan Ristanović) of a popular eponymous science magazine, published late December 1983 inBelgrade,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.
In the early eighties, restrictions inSFR 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 aZX Spectrum or aCommodore 64, though most Yugoslavs were only familiar with a programmable calculator.[2]
According to his own words, some time in 1983,Voja Antonić, while vacationing in Hotel Teuta inRisan, was reading the application handbook for the RCACDP1802CPU and stumbled upon CPU-assisted video generation.[3][4] Since the CDP1802 was very primitive, he decided that aZilog Z80 processor could perform the task as well.
Before he returned home toBelgrade, 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.[5]
His next step was to find a magazine to publish the diagrams in. The obvious choice wasSAM Magazine published inZagreb, 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 theGalaksija 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 entitledRačunari 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.[5] Some 8,000 people wound up ordering the build-it-yourself kits from Antonić.[5] This number may in reality be greater if people who did not purchase any kits (includingPCB andROMs) were accounted for.
Components were provided by various manufacturers and suppliers:[6]
Later, the Institute for School Books and Teaching Aids (Serbian:Zavod za udžbenike i nastavna sredstva), together withElektronika Inženjering, started mass commercial production of Galaksija computers, mainly to be delivered to schools.[7]
Galaksija BASIC is aBASICinterpreter originally partly based on code taken fromTRS-80 Level 1 BASIC, which the creator believed to have been aMicrosoft BASIC.[3] However, after extensive modifications to include video generation code (as theCPU was a major participant to reduce the cost of hardware) and improve theprogramming language, what remained from the original is said to be mainlyflow-control andfloating point code. It was fully contained in 4KBROM "A" or "1". AdditionalROM "B" or "2" provided more Galaksija BASIC commands, assembler, monitor, etc.
The chip labeled as "A" by the creator of Galaksija,Voja Antonić was commonly referred to as "ROM 1" or just "ROM". ROM "A" containedbootstrap code of Galaksija, its control code (rudimentaryoperating system), video generation code (as Galaksija did not have advanced video subsystem itsZ80CPU was responsible even for generatingvideo signal) andGalaksija BASIC.
Fitting all this functionality in 4 KB of 2732EPROM 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" of the Galaksija is a 2732EPROMchip that contains extensions to the originalGalaksija BASIC available inbase 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 (mostlytrigonometric) as well as aZ80assembler and amachine 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 duringbooting. Instead, users had to execute a Galaksija BASIC command to run amachine 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.
CharacterROM ofhome computer Galaksija is a 2716EPROMchip 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.
The character encoding is based onASCII, but has several modifications:
Each character is represented as a 8×16 matrix ofpixels. In thisROM, 8-pixel rows of each character are represented as 8bits of onebyte.[11]
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | A | B | C | D | E | F | |
| 0x | ||||||||||||||||
| 1x | ||||||||||||||||
| 2x | SP | ! | " | # | $ | % | & | 🢖[a] | ( | ) | * | + | , | - | . | / |
| 3x | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | : | ; | < | = | > | ? |
| 4x | ⥢[a] | A | B | C | D | E | F | G | H | I | J | K | L | M | N | O |
| 5x | P | Q | R | S | T | U | V | W | X | Y | Z | Č | Ć | Ž | Š | _ |
| 6x | ||||||||||||||||
| 7x | ||||||||||||||||
| 8x | NBSP | 🬀 | 🬁 | 🬂 | 🬃 | 🬄 | 🬅 | 🬆 | 🬇 | 🬈 | 🬉 | 🬊 | 🬋 | 🬌 | 🬍 | 🬎 |
| 9x | 🬏 | 🬐 | 🬑 | 🬒 | 🬓 | ▌ | 🬔 | 🬕 | 🬖 | 🬗 | 🬘 | 🬙 | 🬚 | 🬛 | 🬜 | 🬝 |
| Ax | 🬞 | 🬟 | 🬠 | 🬡 | 🬢 | 🬣 | 🬤 | 🬥 | 🬦 | 🬧 | ▐ | 🬨 | 🬩 | 🬪 | 🬫 | 🬬 |
| Bx | 🬭 | 🬮 | 🬯 | 🬰 | 🬱 | 🬲 | 🬳 | 🬴 | 🬵 | 🬶 | 🬷 | 🬸 | 🬹 | 🬺 | 🬻 | █ |
Galaksija usedcassette tape assecondary storage. It featured a 5-pinDIN 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 theZX Spectrum. The input signal was routed to theintegrated 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 inZX 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.
In Autumn 1983, Računari's editor contactedZoran Modli, the DJ ofRadio Belgrade 202'sVentilator 202 program, asking him to broadcast software as part of the show.[2] As the Galaksija stored software ondata cassette, Modli was able to alert listeners about an upcoming data broadcast, broadcast the data as sound over the regular FM wave and listeners were able to record the data broadcast using homecassette decks and load the software on the Galaksija via the data cassette drive. Ventilator 202 became a hub of software sharing, with home programmers editing previously broadcast software and sending in the edits for future rebroadcast.[1] Over three years Ventilator 202 broadcast 150 pieces of software for the Galaksija, the Spectrum and Commodore 64, including a digital magazine, named Hack News. Modli notes that while much of the software was written for the Ventilator 202 audience by Yugoslavian authors, plenty of those same authors were alsocracking,pirating andsharing commercial software via the show.[12]
To simplify "do-it-yourself" building and reduce cost, theprinted 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'scase was not pre-built. Instead, the guide suggested it to be built out of theprinted circuit board material (such asPertinax) also used for themainboard. Thus, the top, sides and reinforcements weresoldered 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 usingLetraset 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 ownmemory-mapped addresses that, in most cases, follow the same order asASCII code of the letter on the key. This saved the ROM space by reducing lookup tables but significantly increased the complexity of single-layer keyboardPCB such that it alone required 35 wire links.
