Question

Which of the following register holds memory operand?

• A. Program counter
• B. Memory register
• C. Data register
• D. Instruction register

Hint:

Memory Register (MDR/MBR) stores data being transferred between CPU and memory. Program Counter stores addresses, while Instruction Register stores instructions.

Answer 1

The Correct Option is B

Concept: A computer system contains several registers, each designed for a specific purpose. Some important registers are:
• Program Counter (PC)
• Instruction Register (IR)
• Memory Address Register (MAR)
• Memory Data/Register (MDR or Memory Register) The memory register stores data being transferred to or from memory. Thus it contains the memory operand during memory operations.

Step 1: Understand the role of Program Counter.
The Program Counter stores the address of the next instruction. It does not store operands.

Step 2: Understand the role of Instruction Register.
The Instruction Register stores the currently executing instruction. It does not hold memory operands.

Step 3: Understand the role of Memory Register.
The Memory Register stores data read from memory or data to be written into memory. Hence it temporarily holds memory operands.

Step 4: Identify the correct answer.
Therefore, \[ \boxed{\text{Memory Register}} \] holds memory operands. Hence option (B) is correct.