Mechanisms
- Billiard balls (billiard ball computer); this is an unintuitive and pedagogical example that a computer can be made out of almost anything.
- Light (optical computing)
- Computers can manipulate information as light (rather than electricity or billiard balls).
- Molecules (DNA computing, chemical computing)
- Gears, levels, dials, etc. (analog computer/mechanical computer)
- Neurons (wetware computer)
- Fluid (fluidics)
- Software agents acting under a special set of rules (cellular automata)
- Quantum mechanics (quantum computing)
Read more about this topic: Unconventional Computing