Two independent 8-bit, double-buffered bidirectional I/O ports plus a 4-bit special-purpose I/O port. I/O ports feature programmable polarity, programmable direction (Bit mode),
Four handshake modes, including 3-Wire (like the IEEE-488).
REQUEST/WAIT signal for high-speed data transfer.
Flexible pattern-recognition logic, programmable as a 16-vector interrupt controller.
Three independent 16-bit counter/timers with up to four external access lines per counter/timer (count input, output gate, and trigger), and three output duty cycles (pulsed, one-shot, and square-wave), programmable as retriggerable or nonretriggerable.
;
