I've been kicking around the idea of building a single-board computer around the Zilog Z180 for a while. It fits nicely between my Herring 6502 and Mackerel 68000 projects. It's got the simplicity of an 8-bit processor with a few more bells and whistles that makes it a little more interesting than the original Z80 for me.
I'm starting this project as my entry into the Retro Challenge 2022/10, https://www.retrochallenge.org/, which runs through the month of October. My goal is to get a functional single-board computer from this pile of parts:
This collection may evolve over the course of the challenge, but the quick outline is:
- Z180 CPU with 32KB of ROM, 512KB of RAM, and 18.432 MHz oscillator
- USB or banana plugs plus a 5v switching regulator for power
- EPM7064 CPLD for glue logic and possibly some memory-mapped I/O
- MAX232 for 2x RS-232 compatible serial ports (the UARTS are built in to the Z180)
- 555 timer for power-on reset
- PS/2 keyboard connector breakout
- 40x4 LCD display
- CH376S USB-to-parallel interface board
In previous computer projects, I've relied pretty heavily on my PC as the main I/O with the older hardware. This works great, but in the spirit of the Retro Challenge, I'd like to end up with a system that can stand on its own a little better, hence the addition of the nice big LCD display and the PS/2 keyboard. Instead of loading programs over the PC serial port, I'd like to use the CH376 as a "hard drive" allowing the system to operate without a tether.
If I get all of this working within the month, it'll be a miracle, but in the event that I do, my stretch goal is to get a PCB manufactured and build an enclosure. Should be a fun month!