I’ve been toying with the idea of building a computer from scratch for some time, and have eventually made a start. I have chosen to use the Zilog Z80 series of CPUs as used in the Sinclair ZX80, ZX81 spectrum computers. These are relatively simple devices (by todays standards).
As I am unsure which direction to take the project (there are several possibilities) I’ve decided to build a modular system that is Bus based around the key lines from the CPU. This bus layout will provide the ability to use and swap out different modular components.
As the project progresses I will document the design, but for now here is a peek at the backplane prototype. The pre-built module on the left is a 5V regulator circuit that I had lying around, this will suffice for the prototype. Also included is the reset switch and plenty of smoothing capacitors for each module (probably overkill – but we’ll see). I’ve also left an expansion connector on the right in case it’s needed, but the 9 module slots should be enough.