Instruction Set of 8086 8088 Questions

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31.

The Carry flag is undefined after performing the operation

A

AAA

B

ADC

C

AAM

D

AAD

Correct Answer: D

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32.

The instruction that performs logical AND operation and the result of the operation is not available is

A

AAA

B

AND

C

TEST

D

XOR

Correct Answer: C

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33.

In the RCL instruction, the contents of the destination operand undergo function as

A

carry flag is pushed into LSB & MSB is pushed into the carry flag

B

carry flag is pushed into MSB & LSB is pushed into the carry flag

C

auxiliary flag is pushed into LSB & MSB is pushed into the carry flag

D

parity flag is pushed into MSB & LSB is pushed into the carry flag

Correct Answer: A

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34.

The instruction that is used as prefix to an instruction to execute it repeatedly until the CX register becomes zero is

A

SCAS

B

REP

C

CMPS

D

STOS

Correct Answer: B

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35.

Match the following

A) MOvSB/SW       1) loads AL/AX register by content of a string
B) CMPS           2) moves a string of bytes stored in source to destination
C) SCAS           3) compares two strings of bytes or words whose length is stored in CX register
D) LODS           4) scans a string of bytes or words

A

A-3,B-4,C-2,D-1

B

A-2,B-1,C-4,D-3

C

A-2,B-3,C-1,D-4

D

A-2,B-3,C-4,D-1

Correct Answer: D

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36.

The instructions that are used to call a subroutine from the main program and return to the main program after execution of called function are

A

CALL, JMP

B

JMP, IRET

C

CALL, RET

D

JMP, RET

Correct Answer: C

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37.

The instruction that unconditionally transfers the control of execution to the specified address is

A

CALL

B

JMP

C

RET

D

IRET

Correct Answer: B

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38.

Which instruction cannot force the 8086 processor out of

A

Interrupt request

B

Interrupt request

C

Both interrupt request and reset

D

Hold

Correct Answer: D

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39.

NOP instruction introduces

A

Address

B

Delay

C

Memory location

D

None of the mentioned

Correct Answer: B

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40.

Which of the following is not a machine controlled instruction?

A

HLT

B

CLC

C

LOCK

D

ESC

Correct Answer: B

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