Control unit for an asynchronous serial port, paper tape reader and paper tape punch. Each device uses a 26-way card edge connector. One connector is unused. On a lot of MCU3's, the paper tape circuitry is not present. The serial port uses a COM2502 UART.

Documentation

• P858/P859 REF Ch. 21

MCU3 without paper tape circuitry

MCU3 with paper tape circuitry