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Online MCQ Assignment
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1. When we add two numbers the destination address must always be.
a) some immediate data
b) any register
c) accumulator
d) memory

Answer: c [Reason:] For addition purposes the destination address must always be an accumulator. Example- ADD A,R0; ADD A, @R1; ADD A,@ DPTR

2. 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: b [Reason:] DAA command adds 6 to the nibble, if any of the nibble becomes greater than 9.

3. 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: c [Reason:] SUBB command subtracts with borrow the contents of accumulator with that of the register or some immediate value. So A-R4 is being executed.

4. 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: c [Reason:] When we divide two numbers then AC and CY becomes zero.

5. 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: d [Reason:] In 8 bit operations, if a carry is generated from D6 or D7 bit, then OV flag is set to 1.

6. In unsigned number addition, status of which bit is important?
a) OV
b) CY
c) AC
d) PSW

Answer: b [Reason:] If unsigned numbers operations are involved, then the status of CY flag is important and in signed number operation the status of OV flag is important.

7. Which instructions have no affect on the flags of PSW.
a) ANL
b) ORL
c) XRL
d) All of the mentioned

Answer: d [Reason:] These instructions are the arithmetic operations and the flags are affected by the data copy instructions, so all these instructions don’t affect the bits of the flag.

8. 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: c [Reason:] ANL instruction is used to AND the contents of the two registers and is also used to mask the status of the bits of the register.

9. 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 destination register is greater then that of the source register
c) sets CY=0, if the contents of destination register is smaller then that of the source register
d) none of the mentioned

Answer: d [Reason:] In CJNE command, the pointer jumps if the values of the two registers are not equal and it resets CY, if the destination address is larger then the source address and sets CY if the destination address is smaller then the source address.

10. 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