ronan.pict Portrait of Ronan Gaillard

Shot on black & white film, developed and scanned by me at home.

Ronan Gaillard's Workshop

Embedded systems, retro computers and sailing, from Saint-Malo. Things I built, and how.

ALWAYS UNDER CONSTRUCTION

Now

What I’m working on these days. Last updated in November 2026.

A Z80 computer

My main project right now is a homemade 8 bit computer, built around a Zilog Z80 running at 10 MHz. Everything is through hole DIP chips, like in the 80s.

It’s a motherboard with daughter cards stacked on its expansion bus :

  • a CompactFlash card for storage, with a real time clock and a PS/2 keyboard port
  • a video card built around a 6845, with composite output : 80 × 36 text, or 640 × 200 graphics

The first revision of the motherboard came back from the fab and I’m bringing it up, while the second revision is already on the drawing board. On the software side there is a monitor in ROM written in assembly, an emulator to test everything before it touches real silicon, and the beginning of a small Unix kernel in C.

It’s the grandson of the Z80 computer I built as a student, which booted CP/M. This time I want it to run a Unix. A proper write-up will come once it does.