CPU result register identification: which register records the current arithmetic/logic operation result in classic 8-bit microprocessors like the 8085?

Introduction / Context:
In accumulator-based architectures, most arithmetic and logic operations use a special register called the accumulator (A or ACC). Understanding its role is foundational to assembly programming and CPU design.

Given Data / Assumptions:

• 8085 uses an 8-bit accumulator denoted as A.
• Typical ALU operations read/write the accumulator.
• Status flags reflect properties of the last ALU result (Zero, Sign, Carry, etc.).

Concept / Approach:
The accumulator is the primary destination for ALU outputs. ADD, SUB, ANA, ORA, XRA, INR/DCR, and similar instructions place the result in A, updating flags accordingly. While some instructions store results to memory or other registers, the default pattern is that A receives the current result, making “accumulator” the correct answer.

Step-by-Step Solution:

Verification / Alternative check:
8085 instruction summaries consistently show A as the implicit destination for many arithmetic/logic operations.

Why Other Options Are Wrong:
Program counter holds next instruction address. Stack pointer addresses top-of-stack. “Instruction pointer” is not an 8085 term.

Common Pitfalls:
Believing any general register always receives results; on 8085 the accumulator is central to ALU operations.

Final Answer:
accumulator