Interfacing 8255 to 8086 in I/O Mapped I/O Mode:

 The parallel communication interfaces with the microprocessor. Interfacing 8255 to 8086 in I/O Mapped I/O Mode:

· 8086 has four special instruction in I/O Mapped I/O Mode: IN, INS, OUT,OUTS

· Only 256 address can be generated

· Only lower data bus is used as 8255 is 8-bit device

· Direct addressing mode is used.

Interfacing 8255 to 8086 in Memory Mapped I/O:

· 20 address lines to identify an I/O device

· I/O device is connected to memory register

· Address lines are used by 8255 for internal decoding

· Same control signals are used to access I/O as those of memory.


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