Mode 2
Only group A can be initialized in this mode.
Port A can be used for bidirectional handshake data transfer.
This means that data can be input or output on the same eight lines (PA0 - PA7).
Pins PC4 - PC7 are used as handshake lines for port A.
The remaining pins of port C (PC0 - PC3) can be used as input/output lines if group B is initialized in mode 0 or as handshaking for port B if group B is initialized in mode 1.
In this mode, the 8255 may be used to extend the system bus to a slave microprocessor or to transfer data bytes to and from a floppy disk controller.
Acknowledgement and handshaking signals are provided to maintain proper data flow and synchronisation between the data transmitter and receiver.