Homebrew Computers

A long time goal of mine, building my own computer from scratch, was finally realized in 2015 with the creation of my unnamed Motorola 68000 based single board computer. Originally created on a breadboard, it was finally soldered up onto a protoboard in late 2016. Overcoming the hurdle of actually designing and building the system, rather than just day-dreaming and reading of other peoples successes, was really key. One I had build one computer to a satisfactory level, I found that designing and building others was not as difficult of a task as I initially thought.

After managing to break something in the 68000 system’s wiring and sulking over being unable to find the issue, I ended up working on my second computer. This time the computer would be based around a Zilog z80 processor, as was found in computers such as the TRS-80 and many CP/M based computers. This attempt ended up much more successful, and thanks to a somewhat forethought bus design already has expansion cards and a CF card interface for storage.

The original goal with creating these computers was to have in the end a system that I built and designed from scratch, and that everything run on it was built from scratch. A computer where I know every implementation detail. A concession is made here in the use of off the shelf microprocessors, I haven’t designed a computer with a custom CPU… yet. I don’t really find this a flaw though, does anyone consider any of the home microcomputers of the 80’s lesser computers for making use of existing CPUs rather than boards and boards of TTL logic?

The Computers

  • CKIT-80

    Probably the most complete homebrew system of mine. An 8MHz z80 powered system with 128kB of RAM and 64kB of ROM. This system has a proper expansion bus and a number of expansion cards created for it. It runs a home made monitor/operation system and is able to load and run programs of a FAT16 compact flash card.

  • Unnamed 68000

    The first homebrew I ever made. A Motorola 68000 based computer that started off on a breadboard, and evolved into a single board computer with serial, TV text display, YM2149F sound, and plans for so much more. Currently not working after a failed attempt at adding an IDE disk interface.

  • WIP Handheld 68008

    An attempt at building a portable handheld system. With a 68008 processor, 512kB of ROM and RAM, YM2149F sound, and a 128x64 graphic LCD and keyboard, it's quite the powerful setup.