Why address and data lines are demultiplexed in 8085?

Answer 1

Basically , Demultiplexing is breaking of multiplexed signal .Recall that A/D0 -A/D15 and A16/S3-A19/S6 are the multiplexed signals in 8086.To do so, three demultiplexing latches are used .ALE (Address Enable Latch) is used for strobe Demultiplexing.8086 is 16bit data lines and 20 bit address line microprocessor.BY the Demultiplexing ,we Get A0-A19 separate Address lines and D0-D15 Data lines .

Ajmal Shahbaz

Answer 2

In an 8085, the low order address and the data bus share the same pins. During the first clock cycle of a memory access, the data lines contain the low order address. External hardware is expected to latch that address on the trailing edge of ALE, Address Latch Enable. During the next clock cycle, the data lines either float (for read, S1=1) or change to data value (for write, S1=0).

Answer 3

To demultiplex the data and addess lines on a 8085, you connect a latch to AD0-AD7 and strobe it with ALE. At the falling edge of ALE, AD0-AD7 is guaranteed to represent A0-A7. Following that, AD0-AD7 becomes D0-D7.

Answer 4

The address and data lines in an 8085 are demultiplexed because they are multiplexed to start with. It is necessary to separate them as far as external (outside the CPU chip) logic is concerned.

Note that the address and data bus started separately. They are multiplexed in order to reduce the pin count on the chip. Whether multiplexing has any net value due to the added cost of demultiplexing is debateable, but that is the way it is.

Answer 5

In the 8085, the data bus is shared with the low order address bus. During ALE, which is about the first half T state, starting about one sixth clock after the falling edge of clock, the data bus presents the low address bus. At the falling edge of ALE, about one half clock cycle later, external logic is expected to strobe that value. One half clock cycle later, during the second T state, the data bus becomes the data bus. This saves 7 pins on the chip. (8 pins, minus one for ALE)

Answer 6

There are 16 address lines (8 shared by the data bus), and 8 data lines in the 8085.

Answer 7

Ajmal , tere baap ne demultiplexing ka answer by demultiplexing diya tha , nashe karke baita hai kya

Answer 8

16