Which of the following registers is used to keep track of address of the memory location where the next instruction is located?

The correct answer is Program Counter because it is the dedicated processor register responsible for storing the memory address of the next instruction scheduled to be fetched and executed.

• Step 1 (Definition): As the central processing unit (CPU) runs through a program, the Program Counter (PC) automatically increments after each fetch cycle to point to the next instruction sequence in memory, keeping execution flowing in the correct order.
• Step 2 (Hardware Interaction): The address held in the PC is copied over to the Memory Address Register (MAR) when the CPU is ready to fetch that instruction from RAM.
• Incorrect Options:
  • Instruction Register is incorrect because it holds the current instruction that is actively being decoded and executed, not the address of the next one.
  • Memory Address Register is incorrect because it temporarily holds the immediate physical address currently being accessed for a read or write operation, which can be data or instructions.
  • Memory Buffer Register is incorrect because it contains the actual data payload or instruction bits read from or written to memory, serving as a hardware data buffer.