When it comes to process automation, the go-to part in most industrial settings is a Programmable Logic Controller, or PLC. These specialized computers will have a modern microcontroller running the show, but surprisingly the way they are programmed still has echoes of a time before electronic PLCs when such control would have been electromechanical.
This is a companion discussion topic for the original entry at https://hackaday.com/2024/02/15/a-1960s-plc-gives-up-its-secrets/