The first version of this appeared on Hackaday

As it turns out it was too wide to fit a standard breadboard and so it was put on a diet and is now a .6" 40 Pin footprint.

The module has its own oscillator but can also accept an external clock thanks to a user recomendation. It is currently configured for +5V operation but it can support 3.3V by changing the selected device and recompiling.

The driving though for this, being an old Commodore engineer and knowing how hard it is to get some old parts, is that it could conceivably replace the function of some older parts.