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Q223Moderate8086 & Advanced Processors

The highest priority usage than any other usage is

Answer & step-by-step solution
Correct answer: A. Transfer with LOCK (active low) signal
Quick explanation

A bus transfer protected by the active-low LOCK̅ signal has highest priority because the processor is explicitly preventing other bus masters from taking control during an indivisible/critical bus operation.

LOCK̅ asserted → bus ownership retained for critical operation

Concept & Reasoning

LOCK̅ is used around atomic sequences so shared data cannot be interrupted by another bus master. HOLD requests and coprocessor/data-transfer needs must wait until the locked bus operation completes. This preserves consistency for critical read-modify-write sequences.

How to Solve It in the Exam

LOCK means atomic bus ownership.

Important Exam Point

Priority here is about bus usage/arbitration, not interrupt priority.

Quick Trick

LOCK means atomic bus ownership.

Common Mistake

Choosing HOLD as highest priority even while a locked transfer is active.

Solution diagram – The highest priority usage than any other usage is
Exam tipPriority here is about bus usage/arbitration, not interrupt priority.
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