The Zeta is a minimal Z80 toggle-switch computer. It has a Zilog Z80 microprocessor, 256 bytes of RAM and the only interface is the front panel which directly sets and reads the address and data buses.
There is a video of it executing Euclid’s algorithm:
At the moment, there is only one real source file in this repository, an Inkscape-produced SVG which contains the stripboard layout and lasercut paths along with the image for the box top. In the future I’ll try to add a KiCad circuit diagram. This file doesn’t preview well in github because there are some very thin and zero-width lines – turn on outline mode (View -> Display mode -> Outline) in Inkscape to view it.
Note that this isn’t a foolproof guide to building a replica – there are several parts not recorded yet, such as where to cut the track on the stripboard, and some extra components for the voltage regulators.
There are some errata in the current source – please see the issues section for details.
Why is your circuit diagram in SVG?
Because of the number of DIP chips in this project, it suits stripboard well, and I haven’t found a good program for designing stripboard layouts yet. Fritzing supports small stripboard, but has performance problems when you use a layout as big as this one.
For more detail: The Zeta minimal Z80 toggle-switch computer