HD63B21FP

PIA = peripheral interface adapter , 2MHz , CMOS
Peripheral Interface Adapter provides universal means interfacing peripheral equipment HD6800 Microprocessing Unit MPU . This device capable interfacing the MPU to peripherials through two 8-bit bidirectional peripheral data buses and four control lines. No external logic is required for interfacing to most peripheral devices.

Dokumentacja pod adresem: http://www.wolumen53.com/pdf/HD63B21FP-Hitachi.pdf