The document discusses the demultiplexing of the address and data buses in the 8086 microprocessor, which operates in a time-multiplexed mode for efficient data transfer. It explains the function of the address, data, and control buses, and the use of latch ICs for demultiplexing the 20-bit address lines. Additionally, it outlines the bi-directional nature of the data bus and the control signals that manage data flow.

3. Demultiplexing of Address and Data Bus in 8086 Microprocessor:
 Demultiplexing of Address and Data Bus in 8086 Microprocessor which consists
of three buses: address, data and control buses.
 The address/data buses are operated in time-multiplexed mode.
 The address bus is required to locate memory and I/O devices for data transfer
through memory and I/O read or write cycles.
 The data bus is used to transfer data from microprocessor to memory/I/O devices
or vice versa.
 The control bus provides control signals to memory/I/O devices for data-transfer
operations.

4. Demultiplexing of System Bus in 8086 processor
 The 8086 microprocessor has time-multiplexed 16-bit address/data bus AD15-
AD0 and 4-bit address/status bus A19/S6-A16/S3.
 The ALE signal is used to latch the address of 8086.
 Usually, latch ICs are available with eight separate latches.
 Therefore, three latch ICs should be used for demultiplexing 20-bit address lines.
 Figure shows the circuit diagram for latching 20-bit address lines using three
74LS373 latch ICs. In this arrangement, two ICs are fully utilized and one latch is

6. The 8086 microprocessor has 16-bit time-multiplexed data bus which is
available as Address/Data bus, AD15-AD0.
The data bus is always separated from the address bus by using 74245 buffers.
The data bus is bi-directional and data can be transferred from microprocessor
to memory and memory to microprocessor for memory write and read operations
respectively.
The control signals D̅E̅N̅ and DT/R̅ represent the presence of data on the data
bus and directional flow of data.
These signals are used to connect the chip enable CE and directional pins of
74245 buffers.