In my undergraduate days, telephone switching was transitioning from electromechanical relays to transistors, so there were a lot of cast-off telephone relays available. Along with some of my cohorts at Electrical Engineering, we built a computer out of telephone relays. The relays we used had a switching delay of 12ms — that is, when you put power to the relay, the contacts would close 12ms later. Interestingly, this is in the same timing range as the 4ms maximum firing rate of neurons.
We also acquired a teletype machine which used a serial link running at 110 baud or about 9ms per bit. The question this raised was how do you get 12ms relays to output a serial bit every 9ms? The answer sheds some light on how your brain works, how it is different from ML, and why 65% of your brain is devoted to muscular coordination while less than 20% is devoted to thinking.