I spent 6 years programming 6809 in C, running the embedded system controlling autonomous forklift trucks in a fully-automated warehouse. The vehicles were sent commands to position anywhere in a 500,000 sf warehouse within +-.75" both horizontally and vertically, then extract or place the load. No rails, just a grid of guide wires.

What amazed me from the day I arrived was that the system ran that accurately, using integer measurements, on a processor with 32K ROM and 8K RAM, clocked at 900 Khz. Typical latency was about 2 ms from interrupt to control response, and the relays (FET's weren't up to the task yet) had a mechanical response time of at least 20 ms.

Commutated SCRs switching 300-750 amps inductive load - talk about noise! Have you ever seen 4-0 copper wires visibly jump as the load switched on and off? (That's a welder wire, roughly the diameter of your thumb) 36VDC, not counting the KV and MV transients...

Good days. Fun.