Master–slave J–K flip-flop — input stability requirements A correct and predictable output is achieved from a master–slave J–K flip-flop only if its J and K inputs remain stable while the ________.

Introduction / Context:
Master–slave flip-flops use two level-sensitive latches in sequence. The master latch is typically enabled when the clock is HIGH (for a positive-logic design), and the slave latch is enabled when the clock is LOW, resulting in an effective edge-controlled transfer of data. Understanding when inputs must be stable avoids unintended toggling and races.

Given Data / Assumptions:

• Master enabled on clock HIGH; slave enabled on clock LOW (typical convention).
• Inputs J and K can command set, reset, toggle, or hold depending on their levels.
• We seek the period requiring input stability for correct operation.

Concept / Approach:
Because the master latch is transparent when the clock is HIGH, any change on J or K during that interval can alter what the master captures, leading to incorrect or unpredictable outcomes. Therefore, J and K must be stable throughout the HIGH phase so that the master captures a single, well-defined state to transfer to the slave on the subsequent LOW phase (or edge-equivalent moment).

Step-by-Step Solution:

Verification / Alternative check:
Refer to timing diagrams; when J and K vary during clock HIGH, the master can respond multiple times, producing errors once the slave samples.

Why Other Options Are Wrong:

• Clock LOW: during this time the master is closed; J and K changes do not affect the captured value.
• Slave transferring: phrasing is vague and does not define the critical input window.
• Flip-flop is reset: unrelated to the timing requirement for normal operation.

Common Pitfalls:
Forgetting that level-sensitive windows exist within master–slave designs; assuming they behave like ideal edge-triggered devices.

Final Answer:
clock is HIGH