What is ALE in 8085 in microprocessor?

Answer 1

ALE=Address Latch Enabled.(pin number 30 in 8085)

8085 has a special pin referred as ALE, which indicates whether multiplex bus functions as an address bus or a data bus. Whenever 8085 starts any new operation, ALE signal goes to logic 1 for about 1/2 clock cycle, at about the falling edge of CLK. If ALE=1 then multiplex bus functions as address bus. After that half clock cycle, it goes to logic 0 for nearly 3 or 4 clock cycles. If ALE=0 then multiplex bus acts as a data bus.

The ALE pin helps to enable the latching of lower order ADDR bus. The AD0-AD7 pins, as well as other control pins such as S0, S1, IO/M-, and the other address pins A8-A15, are setup to be correct at the falling edge of ALE.