JK flip-flop operating modes On a standard JK flip-flop, under which input condition is the flip-flop in the hold (no change) state?

Introduction / Context:
The JK flip-flop unifies SR behavior while avoiding the invalid state. Its truth table includes four operating modes: hold, reset, set, and toggle. Recognizing the hold condition is essential when analyzing synchronous state machines and designing gating networks that intentionally suppress state changes.

Given Data / Assumptions:

• Device: edge-triggered JK flip-flop.
• Inputs: J and K are evaluated at the active clock edge (subject to setup/hold times).
• We seek the input combination that preserves the current state.

Concept / Approach:
The JK truth table indicates: J = 0, K = 0 → no change (hold); J = 1, K = 0 → set; J = 0, K = 1 → reset; J = 1, K = 1 → toggle. Thus the explicit hold condition is when both J and K are 0 during the sampling edge.

Step-by-Step Solution:

Verification / Alternative check:
Vendor datasheets and standard textbooks list the JK table, confirming the hold behavior for J = K = 0.

Why Other Options Are Wrong:

• J = 1, K = 0: Set mode.
• J = 0, K = 1: Reset mode.
• J = 1, K = 1: Toggle mode (divide-by-two action under continuous clock).

Common Pitfalls:
Confusing JK with SR (which has a forbidden input) or forgetting that the JK = 11 case toggles, not holds.

Final Answer:
J = 0, K = 0