An absolutely minimal computer project I did in 2016, based on the Zilog Z80 processor. It only has a single 8-LED output device, and I used it to demonstrate how a processor fetches and executes instructions by manually stepping the clock. It has a bunch of LEDs on various Z80 signals to illustrate the process as clearly as possible, but beyond that it's really not at all useful, due to the absence of any real I/O hardware.
I have a dedicated page for the Z80 computer project, with photos of the PCB fabrication process, schematics, etc.
This is my current homebrew computer project. I'm trying to make a simple but useful computer based on the Motorola 68010 processor.