Discuss mode -2 (bi-directional mode) of 8255 (Programmable Peripheral Interface).

Only permitted with port A. Bi-directional bus data used for interfacing two computers and GPIB interface.

INTR: Interrupt request is outputs which requests and interrupt

: output buffer is an output showing that the output buffer has data for the bi-directional bus.

: Acknowledge is an input and output which enables tri-state buffers that an otherwise in their high- impedence.

: The strobe input load data in the port A latch.

IFB: Input buffer full is an output showing that the input latch has information for the eternal bi-directional bus.

INTE: Interrupt enable are internal bits which enable the INTR pin. Bit PC6(INTE1) and PC4(INTE2).

PC2,PC1: Such port C pins are general- purpose I/O pins which are PC0 obtainable for any reasons.