It’s a surprise then to find that a working CPU can be made with just a single NOR gate — which is what is at the heart of [Dennis Kuschel]’s My4th single board discrete logic computer.

By combining NOT and OR gates, you can easily make a NAND gate, an AND gate, a NOR gate, and any other logic you can dream up. Mechanical computing is decidedly old school, but not at these scales.

The designation for more than 400 different digital logic integrated circuits, including NAND and NOR gates, inverters, buffers, decoders, frequency dividers, shift registers, flip-flops and ...