8255 Programmable Peripheral Interface 8255 is a programmable peripheral interface IC which is used as an interface between the external device and the microprocessor for parallel communication. This IC is a 40-pi IC having three ports known as Port-A(PA), Port-B(PB) and Port-C(PC). these ports can operate in various modes. the complete details is given in the following PPTSs. Features of the 8255: It provide three I/O ports All the three I/O ports are latched Port operation is configurable by programming 8255 i.e. writing a control word in CWR BSR- bit set-reset mode allows individual pins of port C to be controlled to be set or reset. PIN diagram of 8255 8255 PPI is a 40-pin IC, it has three 8-bit ports named PA, PB