Difficulty: Easy
Correct Answer: Incorrect
Explanation:
Introduction / Context:
Asynchronous control inputs on flip-flops are labeled PRE (preset) and CLR (clear) or SET and RESET depending on convention. Their purpose is to force the output to a known state for initialization or control.
Given Data / Assumptions:
Concept / Approach:
If a device is said to be in “CLEAR” or “RESET,” its Q output is driven to 0. Therefore, the statement claiming Q is HIGH during CLEAR/RESET is backwards. Only PRE/SET produces Q = 1. Confusion often arises from active-low pin naming (e.g., CLR̄), but the functional outcome at Q is unambiguous.
Step-by-Step Solution:
Verification / Alternative check:
Consult typical 7474 or 74HC74 tables: CLR̄ asserted low drives Q = 0 immediately, proving the point.
Why Other Options Are Wrong:
Common Pitfalls:
Mixing up active-low pin assertions; confusing PRE/SET with CLR/RESET; assuming clock is required for asynchronous actions (it is not).
Final Answer:
Incorrect
Discussion & Comments