1. The instruction that is used to transfer the data from source operand to destination operand is
a) data copy/transfer instruction
b) branch instruction
c) arithmetic/logical instruction
d) string instruction
Explanation: These instructions are used to copy and transfer the instructions.
2. Which of the following is not a data copy/transfer instruction?
a) MOV
b) PUSH
c) DAS
d) POP
Explanation: DAS (Decimal Adjust after Subtraction) is an arithmetic instruction.
3. The instructions that involve various string manipulation operations are
a) branch instructions
b) flag manipulation instructions
c) shift and rotate instructions
d) string instructions
Explanation: The string instructions perform operations on strings such as load, move, scan, compare etc.
4. Which of the following instruction is not valid?
a) MOV AX, BX
b) MOV DS, 5000H
c) MOV AX, 5000H
d) PUSH AX
Explanation: Both the source and destination operands cannot be memory locations except for string instructions.
5. In PUSH instruction, after each execution of the instruction, the stack pointer is
a) incremented by 1
b) decremented by 1
c) incremented by 2
d) decremented by 2
Explanation: The actual current stack-top is always occupied by the previously pushed data. So, the push operation decrements SP by 2 and then stores the two bytes contents of the operand onto the stack.
6. The instruction that pushes the contents of the specified register/memory location on to the stack is
a) PUSHF
b) POPF
c) PUSH
d) POP
Explanation: Since PUSH operation transfers data to stack from a register or memory location.
7. In POP instruction, after each execution of the instruction, the stack pointer is
a) incremented by 1
b) decremented by 1
c) incremented by 2
d) decremented by 2
Explanation: The actual current stack top is poped into the specific operand as the contents of stack top memory is stored in AL&SP and further contents of the memory location pointed to by SP are copied to AH & SP.
8. The instructions that are used for reading an input port and writing an output port respectively are
a) MOV, XCHG
b) MOV, IN
c) IN, MOV
d) IN, OUT
Explanation: The address of the input/output port may be specified directly or indirectly.
Example for input port: IN AX, DX; This instruction reads data from a 16-bit port whose address is in DX and stores it in AX
Example for output port: OUT 03H, AL; This sends data available in AL to a port whose address is 03H.
9. The instruction that is used for finding out the codes in case of code conversion problems is
a) XCHG
b) XLAT
c) XOR
d) JCXZ
Explanation: The translate(XLAT) instruction is used to find codes.
10. The instruction that loads effective address formed by destination operand into the specified source register is
a) LEA
b) LDS
c) LES
d) LAHF
Explanation: The instruction, LEA loads effective address and is more useful for assembly language rather than for machine language.