Man builds computer from scratch, including the CPU

I didn't go back to logic chips, but I built a Z80 machine with 8K RAM and 8K EPROM. I designed all the random addressing and latching logic from HC series chips, and wired it up to sensors and motors to make a maze-running "mouse." Getting the noise off the board was a bitch.

I etched my own two sided board, soldered the vias by hand, soldered all the socket by hand, designed the power circuitry for the motors, etc, etc.

It was fun, and I learned a lot. I wrote my own serial communications routines in Z80 assembler, and soft loaded all the code until I had it right, then blew it into the EPROMs. Got it wrong several times, and eventually plugged the EPROM into its socket the wrong way round and fried it.

I still have it somewhere ...