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.

As an example, let’s consider the AND gate (the others are OR, NOT, NAND, NOR, XOR and XNOR). Electronic gates operate on two nominal voltages, normally 0 V and 5 V, representing the logic 0 ...