Introduction / Context:
Flip-flops form the foundation of synchronous sequential circuits. Among the common types are SR, J–K, T, and D flip-flops. The J–K flip-flop is historically significant and remains conceptually important due to its versatile input behavior and ability to toggle, set, or reset under clock control.
Given Data / Assumptions:
- The term “standard primitive” refers to a basic, canonical building block used in teaching and design libraries.
- We are considering synchronous (clocked) logic circuits.
- We ignore vendor-specific HDL primitives and focus on general digital design concepts.
Concept / Approach:
The J–K flip-flop extends the SR flip-flop by resolving the invalid input condition (S = R = 1). With J = K = 1, the device toggles on the active clock edge, making it convenient for counters and state machines. Many textbooks present J–K, D, and T flip-flops as core primitives; although modern HDL synthesis often maps everything to D flip-flops internally, the J–K remains a recognized primitive in theory and some libraries.
Step-by-Step Solution:
Identify primitive role: J–K provides set (J=1,K=0), reset (J=0,K=1), hold (J=0,K=0), and toggle (J=1,K=1).Clocked operation: state changes only on the specified clock edge (with setup/hold observed).Use cases: counters, divide-by-two stages, configurable state machines.Conclusion: J–K is indeed a standard primitive in synchronous design pedagogy and practice.
Verification / Alternative check:
Cross-check learning resources: most include J–K flip-flops alongside D and T as core devices.
Why Other Options Are Wrong:
Incorrect: Denies widely accepted classification.Only true for asynchronous logic: J–K is clocked; asynchronous refers to preset/clear, not its main operation.Only true for CPLD devices: The concept is technology-agnostic.
Common Pitfalls:
Confusing “primitive” with “most commonly synthesized form” (D FF). Tools often infer D FFs even when behavior is written as J–K.
Final Answer:
Correct
Discussion & Comments