Processor instruction categories Instructions that allow direct control of the processor's condition flags and operating state (for example, enabling/disabling interrupts) are called ________ instructions.

Difficulty: Easy

Correct Answer: processor control

Explanation:


Introduction / Context:
Instruction sets are commonly grouped into categories: data transfer, arithmetic/logic, control flow, and processor control. Understanding these groups helps decode what each instruction affects: memory/registers, ALU results, branching, or processor state/flags.



Given Data / Assumptions:

  • We are focusing on instructions that modify flags or CPU state.
  • Examples include setting/clearing interrupt enables, adjusting stack pointers, or explicit flag manipulation.
  • The question asks for the general category name.


Concept / Approach:
Processor control instructions affect the CPU environment rather than user data. They may set the interrupt flag, clear carry/overflow, change privilege states (on some CPUs), or enter low-power modes. They are distinct from arithmetic/logic operations that might incidentally change flags as a byproduct.



Step-by-Step Solution:

Identify instruction purpose: does it alter CPU control state/flags?Group such instructions under the processor control category.Differentiate from ALU operations whose primary purpose is data computation.Conclude that the correct category is “processor control.”


Verification / Alternative check:
Consult any ISA reference (e.g., x86, ARM) that lists instructions like STI/CLI (x86) or CPS/SEI/CLI (microcontrollers) under system/processor control.



Why Other Options Are Wrong:
“data transfer” moves data among registers/memory. “arithmetic” computes results in the ALU. “bit manipulation” changes bits in operands, not CPU control state.



Common Pitfalls:
Confusing incidental flag updates from arithmetic with explicit flag-control instructions; overlooking privilege restrictions on some control instructions.



Final Answer:
processor control

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