Correct AnswerA. 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.
Detailed Explanation
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 PointPriority here is about bus usage/arbitration, not interrupt priority.
Related Revision Path
This question sits in the revision path Microprocessors and Interfacing → 8086/80286 Bus → Bus Arbitration .
