ZX-81 implementation on iCE40 FPGA(iCESugar board)

Simple and currently incomplete(absent tape in/out) implementation of ZX81 computer with RAM Pack.

It based on ULX3S implementation which based on MiST's implementation.

It easily builds with APIO toolchain.

I'm using only composite output but VGA with scandoubler can be easily copied from ULX3S implementation.

Warning! I did it only for educational purposes. I'm software engineer that got interested with HDL(I've just started with HDL - any dumb things are possible).

Connection diagram

Many PS/2 keyboards works fine with 3.3V power.

If your keyboard doesn't want work from 3.3V - please add 330-470R resistors in series with signal lines.

Issues

Currently, not implemented:

• Loading and saving

• Firing reset from keyboard or button on IOs(but there is reset button on FPGA board)