What is the working principle of the program controller of the washing machine?

In fact, it is microcomputer control. ##Mechanical automatic washing machine: Structure: it consists of electric program controller, water level switch, safety switch (cover switch), drainage selection switch, non drainage stop switch, water storage switch, rinsing selection switch, washing selection switch, etc. Working principle: through various switches, the control circuit is composed to control the voltage output of motor, water inlet valve, drainage electromagnet and buzzer, so that the washing machine can run the program.