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Maximum Mode in the 8086 Microprocessor

In this tutorial, we will learn about the maximum mode of the 8086 Microprocessor, and will also learn the way in which the various dedicated PINs work in maximum mode. By Monika Sharma Last updated : May 16, 2023

When the pin 33 of the 8086 microprocessor is in the reset state, i.e. 0, then the microprocessor functions in the Maximum Mode.

The pins form 24 to 31 are dedicated to these modes. Let us have a look at how these pins function in the maximum mode of the 8086 microprocessor.

Maximum Mode PINs

(RQ' / GT 0) and (RQ' / GT 1)

These two pins are used for bus request and grant purpose. Through these pins, a connection is established between the external peripheral devices and the 8086 microprocessor. Among these two pins, the pin- (RT / GT 0) has higher priority over (RT / GT 1).

LOCK'

This pin is used to lock the internal buses of the microprocessor. When the control of buses is handed over to an external peripheral device, then the microprocessor is locked through this pin. It is an active low signal.

QS0 and QS1

QS stands for Queue status, and as the name suggests, these two pins are used to tell the status of the queue. The status of the queue form the values of these pins is decided as follows:

S2, S1 and S0

Here, the S in each of these pins stands for Status. These three pins: S2, S1, and S0 together tell about the CPU cycle. The different of the values of these pins taken together tell about which CPU cycle is currently running.

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