Assertion (A): Test-and-Set instruction is an atomic hardware instruction used to implement mutual exclusion locks efficiently.
Reason (R): Atomic instructions guarantee that the execution loop cannot be interrupted in the middle of its read-and-modify sequence.
Assertion (A) is True:
The Test-and-Set (TAS) instruction is a hardware-level atomic instruction widely used in operating systems to achieve mutual exclusion and manage critical sections efficiently.
Reason (R) is True:
By definition, an atomic instruction executes as a single, indivisible operation at the hardware level, ensuring that it cannot be interrupted or preempted halfway through its read-and-modify cycle.
Correct Explanation:
Reason (R) correctly explains why Assertion (A) is true: the indivisible, uninterrupted nature of atomic instructions is precisely what allows Test-and-Set to be used safely and effectively for mutual exclusion locks without race conditions.