Organization of Intel 8085 Microprocessors                                                                                                  Print this page
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Address and Data Bus

The AD0 - AD7 lines are used as lower order 8-bit address bus and data bus , in time division multiplexed manner .

The A8 - A15 lines are used for higher order 8 bit of address bus.

There are seven memory and I/O control lines -

RD : indicates a READ operation when the signal is LOW .

WR : indicates a WRITE operation when the signal is LOW .

IO/M : indicates memory access for LOW and I/O access for HIGH .

ALE : ALE is an address latch enable signal , this signal is HIGH when address information is present in AD0-AD7 . The falling edge of ALU can be used to latch the address into an external buffer to de-multiples the address bus .

READY : READY line is used for communication with slow memory and I/O devices .

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