Microprocessors and Microcontrollers (3160914) MCQs

MCQs of 8051 Assembly Language Programming

Showing 11 to 20 out of 25 Questions
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11.

 DAA command adds 6 to the nibble if:

(a)

 CY and AC are necessarily 1
(b)

 either CY or AC is 1
(c)

no relation with CY or AC
(d)

 CY is 1
Answer:

Option (b)

12.

 If SUBB A,R4 is executed, then actually what operation is being applied?

(a)

R4+A
(b)

 R4-A
(c)

 A-R4
(d)

 R4+A
Answer:

Option (c)

13.

 A valid division instruction always makes:

(a)

 CY=0,AC=1
(b)

 CY=1,AC=1
(c)

 CY=0,AC=0
(d)

no relation with AC and CY
Answer:

Option (c)

14.

 In 8 bit signed number operations, OV flag is set to 1 if:

(a)

a carry is generated from D7 bit
(b)

 a carry is generated from D3 bit
(c)

a carry is generated from D7 or D3 bit
(d)

a carry is generated from D7 or D6 bit
Answer:

Option (d)

15.

ANL instruction is used _______

(a)

to AND the contents of the two registers
(b)

to mask the status of the bits
(c)

 all of the mentioned
(d)

none of the mentioned
Answer:

Option (c)

16.

CJNE instruction makes _______

(a)

the pointer to jump if the values of the destination and the source address are equal
(b)

sets CY=1, if the contents of the destination register are greater then that of the source register
(c)

sets CY=0, if the contents of the destination register are smaller then that of the source register
(d)

none of the mentioned
Answer:

Option (d)

17.

XRL, ORL, ANL commands have _______

(a)

accumulator as the destination address and any register, memory or any immediate data as the source address
(b)

accumulator as the destination address and any immediate data as the source address
(c)

any register as the destination address and accumulator, memory or any immediate data as the source address
(d)

any register as the destination address and any immediate data as the source address
Answer:

Option (a)

18.

The instruction, RLA performs

(a)

rotation of address register to left
(b)

rotation of accumulator to left
(c)

rotation of address register to right
(d)

rotation of accumulator to right
Answer:

Option (b)

19.

The instruction, ADD A, #100 performs

(a)

100(decimal) is added to contents of address register
(b)

100(decimal) is subtracted from the accumulator
(c)

100(decimal) is added to contents of an accumulator
(d)

none
Answer:

Option (c)

20.

In which of these addressing modes, a constant is specified in the instruction, after the opcode byte?

(a)

register instructions
(b)

register specific instructions
(c)

direct addressing
(d)

immediate mode
Answer:

Option (d)

Showing 11 to 20 out of 25 Questions
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