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Pin diagram of 8086 Microprocessor

This article contains the Pin diagram of the 8086 microprocessor. In this article, we are going to explain the meaning and purpose of each and every pin of the 8086 microprocessor chip.
Submitted by Monika Sharma, on July 10, 2019

The 8086 microprocessor is a 40 pin IC in which there are 20 pins on each side of the IC. The diagram of the same is as follows:

PIN Diagram of 8086 Microprocessor

Image source: https://images.app.goo.gl/JQw5Fqvjv7mfxSP97


Pin description for 8086 Microprocessor

AD0 to AD15

These lines are multiplexed unidirectional address and status bus. What this means is that at time T1, they carry status signals and in remaining cycles, they carry status signals.

  • S6 is used as bus master, which handles the internal bus control.
  • S5 is used as interrupt flag.
  • S4 and S3 are used to select the segment out of the four segments.
S4S3Segment selected
00ES
01SS
10CS
11DS

BHE' / S7

BHE stands for Bus High Enable. It is an active low signal, i.e. it is active when it is low. It is used to indicate the transfer of data over the higher order data bus (D8 to D15).

BHE' decides whether the data bus will carry 16-bit data or 8-bit data. When BHE’ is enabled (i.e. 0), then the bus will carry 16-bit data, else only 8-bit data through the lower order data bus lines. It is multiplexed with status pin S7.

RD'

It is a read signal used for read operation. It is also an active low signal.

READY

This is an acknowledgment signal from the slower I/O devices or memory. When high, it indicates that the device is ready to transfer data, else the microprocessor is in the wait state.

RESET

By using this pin, the program control returns to FFFF0H.

INTR

This pin is used to receive an interrupt request signal. It is a type of maskable interrupt.

NMI

This is used for Non-Maskable Interrupt Request.

GND

There are two ground pins in the 8086, pin 1 and pin 20.

VCC

The pin 40 is for voltage input.

MN / MX'

This pin is used for minimum or maximum mode of the microprocessor. When this pin is 1, the microprocessor works in minimum mode, and when the pin is at 0, the maximum mode is followed.

Minimum and maximum Mode Pins

Total 8 pins, from Pin 24 to pin 31 work differently for different modes (maximum or minimum).

TEST'

This is also an active low signal. This pin is used for wait instruction when the 8086 is connected with the 8087 microprocessor.

CLK

This pin tells about the clock pulse.






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