Gated S–R storage element classification: A gated S–R latch responds to its inputs only while the enable (gate) is asserted; this level-controlled behavior is considered synchronous (with respect to the gate level), not purely asynchronous. Judge the statement: “The gated S–R flip-flop is asynchronous.”

Introduction / Context:
Storage elements fall into two broad categories: level-sensitive latches and edge-triggered flip-flops. The term “asynchronous” usually refers to inputs that change state without reference to a clock or enable, while “synchronous” means state changes occur under control of a timing signal (clock or enable).

Given Data / Assumptions:

• A gated S–R latch has S and R inputs plus an enable (EN) signal.
• While EN is active, the latch follows S/R; when EN is inactive, it stores.
• No edge-trigger mechanism is present; it is level-controlled.

Concept / Approach:
Because the gated latch admits state changes only when EN is asserted, it is synchronized to the enable level. Although not edge-triggered, it is not “asynchronous” in the sense of acting at any time; it is synchronous to EN. Asynchronous actions would occur regardless of any controlling timing signal (e.g., preset/clear overriding a flip-flop at any time).

Step-by-Step Solution:

Verification / Alternative check:
Timing diagrams show Q reacting to S/R only during active EN intervals; outside those intervals, Q holds, which is textbook synchronous (level-based) behavior, not free-running asynchronous change.

Why Other Options Are Wrong:

• Correct: Contradicts level-controlled nature.
• NAND-based or using Q̄: Gate technology or which output is observed does not alter the synchronous gating concept.
• Depends on propagation delay: Delays affect timing margins, not classification.

Common Pitfalls:
Equating “not edge-triggered” with “asynchronous”; ignoring enable gating; forgetting that “asynchronous inputs” refers to PRE/CLR-type overrides.

Final Answer:
Incorrect