Changes

Mode 1 is a second mode of 8255 I/O mode. In this mode of operation handshaking can used When we wish to use port A or port B for the handshake (strobed) input or output data transfer. Another important think operation, we have to remember initialise that there are two groups port in 8255 PPI, Group mode 1 (port A and Group port Bcan be initialised to operate in different modes, i. Both these groups have one 8-bit port and one 4-bit porte.Group A consist Port-, for e.g., port A can operate in mode 0 and Port CUpper. And group port B consist Port-B and Port CLowerin mode 1). The 8-bit Some of the pins of port C function as handshake lines. For port B in this mode (irrespective of each group can be programmed for whether is acting as an input port or output operation with latched port), PC0, PC1 and PC2 pins function as handshake lines. If port A is initialised as mode 1 input port, then, PC3, PC4 and latched output facilitiesPC5 function as handshake signals. The bits of Port C used Pins PC6 and PC7 are available for handshakinguse as input/output lines.