MC68B21CP – MOTOROLA

The MC68B21CP, manufactured by Motorola, is a Peripheral Interface Adapter (PIA) designed for interfacing peripheral devices to the Motorola 6800 microprocessor family. This specific variant, designated with the “B” in the part number, indicates a higher clock speed compatibility, supporting E-clock frequencies up to 2 MHz, crucial for faster system performance compared to the standard MC6821. The device provides two 8-bit bidirectional I/O ports (Port A and Port B), each with individually configurable data direction registers, allowing for flexible input or output operation on a per-pin basis. Handshake control lines are included on each port to facilitate asynchronous data transfer with peripheral devices. The MC68B21CP operates from a single +5V power supply and is typically housed in a 40-pin DIP package. Internal interrupt logic allows the processor to be notified of peripheral events, streamlining interrupt handling routines.