250+ TOP MCQs on Computer Fundamental Registers and Answers

Computer Fundamentals Multiple Choice Questions on “Registers”.

1. CPU has built-in ability to execute a particular set of machine instructions, called as __________
a) Instruction Set
b) Registers
c) Sequence Set
d) User instructions

Answer: a
Clarification: An instruction is any task which is to be performed by the processor. Instructions are stored in the register. Instruction set is the set of machine instructions.

2. Opcode indicates the operations to be performed.
a) True
b) False

Answer: a
Clarification: Every instruction has an opcode. Additionally, it may have one or more operands and the op code indicates the operation to be performed.

3. The length of a register is called _______
a) word limit
b) word size
c) register limit
d) register size

Answer: b
Clarification: The length of a register is called word size. It tells the number of bits a register can store.
Registers are a part of the CPU.

4. The _________ holds the contents of the accessed memory word.
a) MAR
b) MBR
c) PC
d) IR

Answer: b
Clarification: The MBR holds the contents of the accessed (read/written) memory word.
MBR stands for Memory Buffer Register.

5. Which of the following is not a visible register?
a) General Purpose Registers
b) Address Register
c) Status Register
d) MAR

Answer: d
Clarification: MAR or the memory address register is not a visible register. This register is user inaccessible. It contains the address of the memory block to be read or written to.

6. Which of the following is a data transfer instruction?
a) STA 16-bit address
b) ADD A, B
c) MUL C, D
d) RET

Answer: a
Clarification: The instruction STA 16-bit address is a data transfer instruction.
STA means Store in Accumulator.

7. What is correct instruction if you want the control to go to the location 2000h?
a) MOV 2000h
b) MOV A, 2000h
c) JMP 2000h
d) RET 2000h

Answer: c
Clarification: The JMP instruction is used to move to a particular location. In 8085 microprocessor, JMP statement tells the processor to go to location 2000h (here).

8. What kind of a flag is the sign flag?
a) General Purpose
b) Status
c) Address
d) Instruction

Answer: b
Clarification: Sign flag is a type of status register or the flag register. It is used to indicate the sign of certain bits.

9. The number of sign bits in a 32-bit IEEE format __________
a) 1
b) 11
c) 9
d) 23

Answer: a
Clarification: There is only 1 sign bit in all the standards. In a 32-bit format, there is 1 sign bit, 8 bits for the exponent and 23 bits for the mantissa.

10. New CPU whose instruction set includes the instruction set of its predecessor CPU is said to be ___________ with its predecessor.
a) fully compatible
b) forward compatible
c) compatible
d) backward compatible

Answer: d
Clarification: The CPU is called backward compatible since it contains the instruction set of its predecessor. Manufacturers tend to group their CPUs into families having similar instruction set.