Comment by retrac

Very cool. I've been sketching out a relay computer myself. Mostly unbuilt but I have tested a variety of circuits implementing gates, latches, oscillators, flip flops, counters, registers all using only SPST reed relays.

I'm fixated on speed. I connected some reed relays in a 3 stage ring oscillator and it ran at 1.8 kHz. That has me thinking that with a pipeline 100 instructions a second might be attainable. Reed relay logic seems to be fast enough for a UART at 50 baud. Teletype interactivity is a stretch goal.

My program counter is also 12 bits! And I've also been using Digital to simulate parts of it. Great tool for that.

The current design is RISC-like with a 12 bit word requiring 4 cycles for most instructions. I have an old version of the design specified in gate level Verilog. I should publish that. Though I'm forever tinkering with the control such that it'll probably never be done. Karnaugh maps are like Sudoku.