Logical gates modeled as simple switches. Similar setups where AND is wires in series and OR is wires in parallel also work with Sprockets and Chains, Relays, Vacuum Tubes, Bipolar Junction Transistors, and Field Effect Transistors. You only need AND, OR, and Invert for functional completeness. Actually, just OR and Invert would do the trick as well like with Minecraft Redstone where AND is created with NOT((NOT A) OR (NOT B)).
