CPU registers and results Which processor register keeps track of the current result of arithmetic or logic operations so that new results can be stored and used immediately by subsequent instructions?

Introduction / Context:
Classic CPU architectures revolve around a small set of special-purpose registers with distinct roles. The accumulator is historically the workhorse register for arithmetic/logic, especially in accumulator-based instruction sets (for example, 8051, 8085).

Given Data / Assumptions:

• Many instructions implicitly use a specific register for ALU operations.
• Subsequent instructions often read the most recent result without extra moves.
• Other special registers serve flow control and stack management.

Concept / Approach:
The accumulator is the primary destination/source for arithmetic and logic operations. While modern RISC machines are general-register architectures, the conceptual role remains: a register holds the latest ALU result for immediate reuse. The program counter/instruction pointer track addresses, not data results; the stack pointer tracks the top of the stack.

Step-by-Step Solution:

Verification / Alternative check:
Examine instruction sets (for example, 8085: ADD r adds register r to accumulator A; result in A). Documentation confirms its result-holding role.

Why Other Options Are Wrong:

• Stack pointer: Tracks stack top address.
• Program/instruction pointer: Hold the next instruction address, not results.

Common Pitfalls:
Assuming every architecture uses an explicit accumulator; some use general registers, but the question context matches accumulator-based designs.

Final Answer:
accumulator