ALE is a control signal of 8085 MPU.8085 is a 8-bit
microprocessor which have 16-bit address bus among them
lower 8-bit are multiplexed.So while MPU executes read or
write operation it needs to demultiplexed.ALE control signal
used to demultiplexed the lower order address and data bus.
address latch enable...in the case of microcontroller (8051)
& microprocessor 8085 the data line & low order 8 bit
address lines are multiplexed.in order to geting address
from this line we uses a latch.ALE is the line connected to
this latch saying that the take the address from the line.
NB: this is used only when we connecting our micro
controller to external mem.
8085 processor has 16 address lines for 16 bit address of a
memory location. Out of this 16 address lines 8 adress
lines are solely dedicated to transfer 8 higher order
address bits while the remaining lower order 8 bits of the
address are sent through another 8 lines multiplexed with
the 8 bit data lines. It is the control signal ALE to be
sent by the processor in appropriate time to indicate the
operation of this 8 bit multiplexed bus whether it will be
used to send the lower order 8 address bits or to send the
8 data bits. How it is indicated ? Making ALE control HIGH
the multiplexed 8 bit bus will act as address bus while
making ALE control LOW the same 8 bit multiplexed bus will
act as data bus. Thus, ALE = 1 makes the address latched
i.e. latch enable and ALE = 0 makes the adress bus disable
but making it data bus enable. In this sense, this 8 bit
bus better should be said as data bus.
ALE is used to indicate the beginning of any operation.it is
a positive going pulse used primarily to latch lower order
address from multiplexed bus(AD0-AD7)and generate seperate
set of eight address lines A0-A7.
it is an output status signal.it tells that when data is
present and when address is present on the multiplexed
when ALE=1(it means address is present)
when ALE=0(it means data is present on multiplexed A/D
ALE stands for address latch enable.this is a positive
going pulse every time when the 8085 microprocessor is in
operation.it indicates the bits on AD0-AD7 are address
bits.this signal is used to latch the lower order address
from the multiplexed bus,and generates separate set of 8-
address lines A0-A7.
ALE stands for "address latch enable"
8085 is a 8 bit microprocessor with 16 address lines.
Among those 16 address lines lower order address lines are
multiplexed with the 8 data lines....when this ALE is
enabled it means that address is being flown through those
multiplexed lines and if it is disabled then data will be
flown through the multiplexed lines