Instead of going with silicon-based switching (ie: transistors) this 4-bit adder uses mechanical relays. We like it for its mess of wires (don’t miss the “assembly” page which is arguably ...

The 4-bit CPU has a Harvard RISC architecture built entirely from 74HCT series logic mounted on a two-sided PCB using only through-hole parts. With 2K words of instruction RAM and 2K words of ...