In Intel 8085A microprocessor architecture, which register keeps track of the memory address of the next instruction (next op-code) to be fetched and executed by the CPU? Provide the most appropriate register name used for instruction sequencing in an 8-bit microprocessor.

Introduction / Context:The instruction execution cycle of an 8-bit microprocessor such as the Intel 8085A depends on a special register that points to the address of the next op-code. Understanding which register performs this role is fundamental to microprocessor programming, debugging, and system design.

Given Data / Assumptions:

• Target device: Intel 8085A (8-bit CPU).
• We are asked which register holds the address of the next instruction.
• Typical internal registers include the accumulator, general-purpose registers, the stack pointer, and the program counter.

Concept / Approach:The CPU fetches the next instruction from memory at an address held in a dedicated sequencing register. After fetching, the CPU normally increments this register so that it points to the subsequent instruction, unless a branch, jump, call, or interrupt modifies the control flow.

Step-by-Step Solution:

Verification / Alternative check:Observe any program that uses a jump or call: the destination address is loaded into the program counter, immediately changing the next fetch location, confirming the PC's role.

Why Other Options Are Wrong:

• Stack pointer: references stack memory, not instruction addresses.
• Instruction pointer: not the conventional 8085A term; PC is used.
• Accumulator: an 8-bit data register for ALU operations, not addressing.

Common Pitfalls:Confusing PC with SP when analyzing subroutine calls and returns; remember calls push the current PC to the stack, and returns pop it back.

Final Answer:program counter