Question

Match List - I with List - II

List - I (Register)	List - II (Function)
A. Memory Address (MAR)	III. Holds address of the active memory location
B. Memory Buffer (MBR)	I. Holds information on its way to and from memory
C. Program Control (PC)	IV. Holds address of the next instruction to be executed
D. Accumulator (A)	II. Accumulates results and data to be operated upon

• A. A-IV, B-III, C-I, D-II
• B. A-I, B-IV, C-III, D-II
• C. A-III, B-I, C-IV, D-II
• D. A-III, B-IV, C-I, D-II

Hint:

To distinguish MAR and MBR: MAR is the "Map" (holds the address/location), while MBR is the "Box" (holds the actual contents/data).

Answer 1

The Correct Option is C

Concept: CPU registers are high-speed storage locations within the processor. Each register has a specific dedicated role in the Fetch-Decode-Execute cycle of the Von Neumann architecture.

Step 1: Matching Memory Registers.

• MAR (Memory Address Register): Its job is to hold the memory address of the data or instruction currently being accessed. This matches with III.
• MBR (Memory Buffer Register): Also known as the Memory Data Register (MDR), it acts as a container for the actual data being read from or written to memory. This matches with I.

Step 2: Matching Control and Processing Registers.

• PC (Program Counter): This register keeps track of where the CPU is in the program by holding the address of the next instruction. This matches with IV.
• Accumulator (A): This is part of the ALU (Arithmetic Logic Unit). It stores the intermediate results of arithmetic and logical operations. This matches with II.

Step 3: Final Mapping.
Combining these matches: A-III, B-I, C-IV, D-II. This corresponds to Option (3).