My neighbor had a custom made keyboard for his ZX spectrum, based on reed switches: https://en.m.wikipedia.org/wiki/Reed_switch https://en.m.wikipedia.org/wiki

My neighbor had a custom made keyboard for his ZX spectrum, based on reed switches: https://en.m.wikipedia.org/wiki/Reed_switch https://en.m.wikipedia.org/wiki/Reed_switch Mine was manufactured at a tractor plant, and one had to press really hard on switch a to get a response.