I've very less knowledge in electronics, I've read that a latch is a simple circuit that stores 1 bit of data (or state).
A Latch is a circuit that has two stable states and can be used to store state information.
That means it is a noun or a simple thing.
But while reading microprocessors (8085), in Timing and Control, there's a signal called ALE (Adress Latch Enable).
And I read this line –
The ALE is a pulse signal, used to latch the address from AD0-AD7.
Now in the line above, the term latch is used as a verb. I don't know what exactly mean by that line above. What is mean by latching something?
So here my question is what is a latch? And what is the meaning of the line above? And what is ALE?
Best Answer
Latch can be used as a noun or as a verb. You got it right.
ALE - Some IC's overlap Address bus and Data bus pins to minimize the number of pins needed. That means one pin can be used as an address pin or as a data pin depending on the current state of the bus. For the logic to work properly address value should be present for the whole read or write operation. To accomplish this the mentioned IC has latches (memory registers) inside. ALE signal stores the pins' state into internal address registers (latches) of this IC. After that the bus can be switched to deliver data on these same pins, that used to carry the address a moment ago.