A Z80 design of my own, though with inspiration from multiple sources. Goal was to correct shortcomings of a board I designed in '98 and give me an easily-extensible platform on which to run CP/M and tinker. It's modular in the spirit of an RC2014 but not requiring any modules at all for what I considered to be "core functionality", just omit undesired initial functionality as you populate the board and add it later if needed.
So far runs as expected and I'm coding away on a BIOS as time allows. If everything works to my satisfaction in the end I may offer some kits on Tindie if there's any interest and if I have time to make a Rev 2 board. This board has 2 bugs requiring 2 jumper wires -- a mis-sized footprint for the coaxial power connector, fixed by drilling, and a system clock trace net that got split into 2 separate nets by a KiCAD typo. There's also bit of physical placement tweaking I'd like to do for practicality.
But it runs like a champ! After the docs and BIOS are complete next up is a mass-storage module (CF or SDD) and getting CP/M on the beast.