Galaksija is a small home microcomputer designed in 1983 in Belgrade by Voja Antonić. Meant as a DIY computer it was later also manufactured on production lines and was the most popular domestic home computer. Original circuit is based on a Zilog Z80 microprocessor and requires no application-specific integrated circuits, implementing the digital circuit with general purpose discrete logic chips.
For anyone wanting to build a Galaksija today the original design has a number of problems. It's based on obsolete 74LS logic, which is hard to buy these days. The circuit also depends on a few unspecified signal timing details of the Z80 microprocessor, meaning that it will not work with all Z80 CPUs you can get today.
This page contains information about CMOS Galaksija, my remake of the original circuit using modern 74HC-series chips. It also fixes the Z80 timing issues (at the cost of one additional integrated circuit) and adds a composite video output that is compatible with modern TVs.
CMOS Galaksija was featured at several events:
- 29th Chaos Communication Congress, Hamburg, Germany. (December 2012)
- Vintage Computer Festival Europe, Munich, Germany. (May 2007)
- International Festival of Computer Arts, Maribor, Slovenia. (May 2007)
Please see this directory for the latest version of the hardware design. The archive includes the full schematic and a two-layer PCB layout for the motherboard and the keyboard. It also includes binary ROM images for writing into EPROMs.
Schematic and the PCB layout can be edited with tools from the gEDA project. There is also a read-only Postscript version included that can be used for printing.
The incomplete Galaksija ROM disassembly
This is an assembly source file automatically generated from binary ROM image with z80dasm. Human-readable comments were gradually added later by me while working on CMOS Galaksija (with the wonderful Incomplete Spectrum ROM Assembly as a style guide).
This source can be assembled into a binary identical to the original ROM image with a Z80 assembler like z80asm.
Over the years I have also published many English blog posts that describe intimate details of Galaksija's circuit.
I gave a number of talks about Galaksija. You can watch the following on-line:
- The ultimate Galaksija talk at 29th Chaos Communication Congress, Hamburg, Germany. (December 2012)
- Mikroračunalnik Galaksija at Kiberpipa, Ljubljana, Slovenia. (May 2007)
Galaksija development tools also contain a number of demos written in assembly. You can watch recordings of some of them below:
Watch an early screencast comparing drawing speed of BASIC versus machine code and some video sync tricks accessible from BASIC.
Galaksija resources elsewhere on the web
Other Galaksija remakes: