Motorola MC14500B

The Motorola MC14500B Industrial Control Unit (ICU) is a CMOS one-bit microprocessor designed for simple control applications. It is well-suited to the implementation of ladder logic, and thus could be used to replace relay systems and programmable logic controllers, also intended for serial data manipulation. Processor supports 16 commands, operating at 1 MHz frequency. The MC14500B unit does not include a program counter (PC); a clock signal drives a separate PC chip, therefore the size of supported memory is dependent on the implementation of that chip.

The amateur computer WDR-1 (512 bits of RAM, LED I/O, keyboard) is based on this processor.

The ICU architecture is similar to that of the DEC PDP-14 computer.