Synchronous SR inputs in a gated flip-flop Why are the S (set) and R (reset) inputs of a gated SR flip-flop referred to as synchronous inputs?

Introduction / Context:
Gated SR and JK flip-flops often include a level-sensitive gate (or clock enable) that qualifies when data inputs can affect the internal state. Inputs qualified by the clock or gate are called synchronous, while separate preset/clear pins are asynchronous.

Given Data / Assumptions:

• Device: gated SR flip-flop (or latch) with gate/clock input.
• Inputs: S and R affect the state only when the gate is asserted.
• Asynchronous inputs (if present) are distinct lines such as PRE and CLR (usually active-LOW).

Concept / Approach:
Synchronous means “timed with” the clock/gate. Therefore, S and R are effective only during the interval when the gating signal is active. Outside that window the storage element holds its previous state regardless of S and R levels (barring asynchronous controls).

Step-by-Step Solution:

Verification / Alternative check:
Examine datasheets: timing diagrams show input setup/hold relative to the gate (or clock), further underscoring synchronous behavior for S and R.

Why Other Options Are Wrong:

• Independent of the gate: That would define asynchronous, not synchronous.
• Asynchronous and always override: Describes PRE/CLR, not S and R on a gated input.
• Power-on only: Not related to normal synchronous operation.

Common Pitfalls:
Mixing up latch gating with asynchronous preset/clear, or assuming S/R act at any time without regard to the enabling level.

Final Answer:
They must occur with the gate.