Rifle and programmable logic controller: what they have in common

1. Step 1. Rifle — evolved into — Assault rifle. An automatic weapon.
2. Step 2. Assault rifle — has part — Spring. A return spring.
3. Step 3. Spring — is part of — Pinball. A plunger.
4. Step 4. Pinball — has part — Electromagnet. Flippers are solenoids.
5. Step 5. Electromagnet — is part of — Relay. An electromagnet switches the contacts.
6. Step 6. Relay — evolved into — Programmable logic controller. It replaced relay cabinets.

Open Evothings