In flip-flop terminology, an input that is acted upon only when a qualifying enable or trigger (such as a clock/enable) is present is called a synchronous input. Is the statement “such an input is asynchronous” accurate?

Introduction / Context:
Digital storage elements, such as latches and flip-flops, are controlled by signals that determine when input data may affect the stored state. Two broad classes of control exist: synchronous (governed by an enable or clock event) and asynchronous (acting immediately, regardless of clock). Understanding this distinction is essential when reading datasheets and designing robust synchronous systems.

Given Data / Assumptions:

• The statement claims that an input accepted only with an enable/trigger present is “asynchronous.”
• Typical flip-flops include a data input that is sampled on a clock edge (synchronous) and may include direct set/reset inputs (asynchronous).
• Enable signals for latches and clocks for flip-flops control when data is allowed to pass or be captured.

Concept / Approach:
Synchronous inputs are qualified by a clock or enable. The device responds only at defined times (level-open window for latches or an edge for flip-flops). Asynchronous inputs bypass this timing control and can change the state at any time, independent of the clock, which is why they are commonly used for reset or preset functions.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets for common devices (e.g., 7474) explicitly list D as clocked (synchronous) and list asynchronous preset/clear separately. Timing diagrams show D is sampled only on edges; asynchronous inputs take effect immediately.

Why Other Options Are Wrong:
Calling the statement “Correct” reverses the established definitions. Restricting the claim to latches or edge-triggered devices does not fix the core error; synchronous vs asynchronous is independent of level vs edge behavior.

Common Pitfalls:
Confusing “enable present” with “asynchronous control.” Also, assuming any control not named “clock” is asynchronous—gated latches still operate synchronously with respect to their enable.

Final Answer:
Incorrect