Hold condition of an SR/JK flip-flop Under which input condition does a flip-flop hold (retain) its current state without changing?

Introduction / Context:
All basic latches and flip-flops provide a hold condition in which the stored bit is preserved. Recognizing the hold input combination is essential to understanding timing diagrams and writing correct state-transition tables.

Given Data / Assumptions:

• Device: SR or JK flip-flop (synchronously gated).
• Active inputs change state only when the clock/gate permits.
• We consider the logical activation of set and reset (polarity depends on the specific device).

Concept / Approach:
The hold condition is the case where neither set nor reset is asserted. For an SR latch, that corresponds to S=0 and R=0 if inputs are active-HIGH (or S=1 and R=1 if inputs are active-LOW). With no command to set or reset, the device maintains its previous Q and Q̄ values across the clock interval.

Step-by-Step Solution:

Verification / Alternative check:
Consult SR truth tables: the line corresponding to “no active S or R” is labeled “no change” or “hold.” The same concept applies to JK when J=K=0 (no change).

Why Other Options Are Wrong:

• Both S and R active: For SR, this is invalid or forbidden (or invokes an asynchronous override if present).
• Only S active: Sets the flip-flop.
• Only R active: Resets the flip-flop.

Common Pitfalls:
Forgetting the active level of inputs and misreading the “forbidden” SR condition as a hold; in JK, J=K=0 is the explicit hold state.

Final Answer:
no active S or R input