Here are a few interesting projects that I’ve found to build a basic Z80 computer on a breadboard.
Bread80 is a really well explained blog describing the author’s project in creating a Z80 computer. This is the one that I am following along with!
L Break into Program also has a nice write-up of a breadboard-based Z80 computer – here is part one. The website has loads more useful information on retro computers and programming, including ZX Spectrum resources.
Finally, this project on hackaday also looks interesting – it uses an Arduino Atmega32A as an “universal” I/O emulator.
If you want to skip some of the theory and breadboard-wiring, you can buy kits instead. These offer a modular way to build a Z80 single-board computer from discrete components – here are some more details.
Let me know in the comments if you find any more!
Image Credits: limpfish