What is the purpose of ALE signal?

The Address Latch Enable (ALE) signal is used in microprocessor and microcontroller systems to demarcate the time when the address bus holds valid address information. When ALE is activated, it signals external latches to capture and store the address present on the bus, allowing the processor to switch the bus for data transfer without losing the address information. This is particularly important in systems where the address and data share the same physical lines, ensuring accurate communication between the processor and memory or peripheral devices.