Question

state the use of status signals in maximum mode

Answer 1

The maximum mode signals of 8086 are listed in table below. The 8086 can made to work in maximum mode by grounding MN/MX. In maximum mode, the pin 24 to pin 31 are defined as follows. 

NameDescription/FunctionType
RQ/GT1, RQ/GT0Request/Grant bus access controlBidirectional
LOCKBus priority block controlOutput, Tristate
S2, S1, S0Bus cycle statusOutput, TristateQS1, QS0Instruction queue statusOutput


S0, S1, S2: These are status signals and they used by the 8288 bus controller to generate the bus timing and control signals. The status signals are decoded as shown in table:
Status SignalMachine Cycle
S2
S1
S0000Interrupt acknowlegement001Read IO port010Write IO port011Halt100Code access101Read memory110Write memory111Passive/Inactive
RQ/GT0, RQ/GT1(Bus Request/Bus Grant): These requests are used by the other local bus masters to force the processor to release the local bus at the end of the processor's current bus cycle. These pins are bidirectional. The request on GT0will have higher priority than GT1.

Answer 2

The maximum mode signals of 8086 are listed in table below. The 8086 can made to work in maximum mode by grounding MN/MX. In maximum mode, the pin 24 to pin 31 are defined as follows. 

NameDescription/FunctionType

RQ/GT1, RQ/GT0Request/Grant bus access controlBidirectional

LOCKBus priority block controlOutput, Tristate

S2, S1, S0Bus cycle statusOutput, TristateQS1, QS0Instruction queue statusOutput