ALE signals means 'address latch enable' .If its value is 1,it enable the latch but doesn't store. and when its value is 0 it store the contents of latch.
address latch enable
The ALE signal on the 8085 is Address Latch Enable. When ALE is true, the data bus contains the low order address information for the current bus cycle. External hardware, i.e. latches, are expected to follow the data bus when ALE is true. At the point where ALE goes false, at approximately the rising edge of CLK, the latches are expected to latch and hold the data bus, presenting it to the outside world as the low order address bus.
ALE is a signal that means that the data bus contains the lower order address bus values. External hardware should strobe the data bus during ALE time, and lock it on the falling edge of ALE.
ALE Address Latch Enable
ALE, or Address Latch Enable, tells hardware logic that the data on the data bus represents address information that should be latched. This is a technique used called multiplexing, and it allows for the pin count on the processor chip to be reduced.
EA - External Access PSEN - Program store Enable ALE - Address Latch Enable RST - Reset WR - RD
The 8085 microprocessor is used IC 74LS373 to latch the address of 8085. Basically latch is consists of 8 flip flops. Generally we used D-flip flops (Delay).The clock of these flip flops are connected together and available as a output pin called enable.Working : The address will appear on AD0 AD7 lines. The ALE will go high and forcingEnable = 1. This will make latch enable and ready to work. Before address disappears ALE = 0. This will make latch disable. AD0 - AD7 will now be used as data bus.Hence, AD0 - AD7 (low order) address bus of the 8085 microprocessor is multiplexed (time-shared) with the data bus. The buses need to be demultiplexed.
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ale