Jap European Chilly Conflict–period computing has a poor fame. The image is one in every of a panorama affected by uninspired makes an attempt to repeat American IBM PCs, British ZX Spectrums, and different Western computer systems. However then there was Yugoslavia’s Galaksija, a really impressed bid to place a pc into the palms of normal comrades.
Galaksija is a Z80-based, 8-bit DIY machine, cleverly designed in order that its invoice of supplies meshed precisely with what a Yugoslavian was capable of import from Western Europe. Throughout its transient heyday, 1000’s have been constructed, resulting in commercially assembled Galaksijas discovering their method into properties and colleges throughout the nation. And now you may do this scrappy machine for your self.
As a retrocomputing nerd, once I noticed early final yr that the Galaksija was being reissued as an entire package by way of
Crowd Supply, I positioned an order on normal rules. However my curiosity was actually piqued a number of months later once I attended a fascinating talk on Yugoslavian computing given by Vlado Vince on the HOPE hacker conference. As delays stored pushing the supply of the Crowd Provide package again into an indefinite future, I bumped into Vince on the Vintage Computer Festival East final April, and he slipped me a spare Galaksija printed circuit board and a hyperlink to his modern bill of materials. Figuring it was plain crusing from there, I canceled my Crowd Provide package order and set off alone.
Full plans for the Galaksija have been first printed in 1983 in an article within the laptop journal
Računari u vašoj kući as a three way partnership between the Galaksija’s designer, Voja Antonić, and the journal’s editor, Dejan Ristanović. (An English translation of the article was printed by No Starch Press in 2018 inPoC||GTFO Vol. 2.) Yugoslavians who didn’t wish to strive ordering elements from abroad might get them organized from Antoić and Ristanović.
The Galaksija initially used a single-sided PCB, however a number of years in the past Antoić launched a two-layer revision. This primarily eliminates the necessity to solder in jumper wires, rushing up development significantly. The brand new model makes two different tweaks, with a brand new set of footprints for video and audio jacks, and an additional capacitor to repair a timing problem when utilizing the trendy variant of the Z80 CPU chip.
However even with these decadent concessions, you’ll nonetheless be getting a construct expertise that received’t really feel like something you’ve ever made should you’re underneath 50. For starters, most of the resistor values used will appear slightly off. Fashionable designs usually revolve across the
E6 series of ohmic value multipliers—1.0, 1.5, 2.2, 3.3, 4.7, and 6.8. However you’ll want an E24 set readily available, as a lot of Galaksija’s resistors have multipliers like 1.8 or 6.2.
The Galaksija makes use of comparatively few elements, counting on its CPU to do a whole lot of the work that’s carried out by devoted circuitry in different residence computer systems. Two EPROMs (recognizable by the window that permits their silicon to be uncovered to ultraviolet gentle for information erasure) retailer the working system, whereas a 3rd EPROM shops graphical character information.James Provost
Subsequent, like some
other early home computers, the Galaksijia has minimal video circuitry, relying largely on the CPU to generate analog tv alerts. This helped enormously in retaining its part prices throughout the authorized import restrict, though the extra computing overhead did gradual the Galaksija down considerably. The Galaksijia generates a European PAL TV sign, which I used to be in a position to make use of with a flat-screen monitor, due to the magic of my RetroTink-2X Pro, an exquisite little field that may convert many out of date video alerts to HDMI. You too can strive plugging it into an outdated analog American CRT TV, as a result of its pure black-and-white sign is compatible-ish with the NTSC normal, however I discovered this requires a forgiving TV and a very dab hand on the vertical maintain management.
However the massive complications are the Galaksija’s ROMs, with three chips in two flavors. These chips are
erasable programmable ROMs, or EPROMs, which could be electronically written to, as with trendy EEPROM chips. However to erase an EPROM you’ll want to blast it with ultraviolet gentle for a couple of minutes by way of slightly round skylight window on high of its package deal.
Confronted with a looming deadline, I did the one logical factor: I cheated.
I hadn’t dealt with an EPROM for the reason that Eighties, and that was a damaged one I used to be given to take a look at underneath my junior scientist microscope. I used to be capable of supply some on eBay, however quickly realized that getting the chips was solely step one in every of an advanced course of. Like many manufacturers, I exploit an affordable and cheerful
TL866-based ROM programmer. Out of the field, these can’t provide the upper voltage wanted to program an EPROM, though there are directions on-line for a hardware modification to permit this. However I used to be struggling to even learn the chips to confirm that they have been clean. Was there an issue with my instrument chain, or with the chips themselves? If my Galaksija didn’t activate correctly, how would I do know if the issue lay with the EPROMs or how I’d populated the board?
As seen on this diagram, tailored from EPROM inventor Dov Frohman’s 1971 paper for the IEEE Journal of Solid-State Circuits, every little bit of reminiscence is a transistor with an unconnected gate electrode [dark rectangle]. To set a bit, the gate is charged by making use of a excessive breakdown voltage between the transistor’s supply and drain, trapping electrons. The sphere produced by the trapped gate electrons creates a conductive layer within the silicon substrate. The gate is reset by exposing the floor to penetrating UV gentle.James Provost
Confronted with what regarded like a prolonged sequence of trial and error, and a looming deadline for this text, I did the one logical factor: I cheated. I emailed Vince, who conveniently additionally lives in New York Metropolis, and he volunteered to come back into the
IEEE Spectrum workplace, alongside together with his UV EPROM eraser, hacked TL866 programmer, and a few programmed ROMs for testing. After about two hours of troubleshooting, together with tossing a dud chip, my Galaksija was displaying its READY immediate. Actually, everybody ought to have an 8-bit Yugoslavian DIY laptop man: You might not want them for years, however whenever you do, you’re actually glad you might have them
You don’t must know Serbian or Croatian to program the Galaksija. It has a model of Primary utilized by the
TRS-80 Model 1, and therefore English key phrases. Software program is saved and loaded by way of an audio jack initially supposed to interface with tape recorders, and there are collections of Galaksija software available for download, together with classics like Tetris. The Galaksija might not be as well-known as Western 8-bit machines just like the ZX Spectrum or Commodore 64, however attending to know it’s a good way to see how individuals somewhere else joined the digital revolution and the way motivated engineering can transcend main obstacles.
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