Difficulty: Easy
Correct Answer: Bistable multivibrators
Explanation:
Introduction / Context:Multivibrators are categorized by the number of stable states they possess. Recognizing where flip-flops like S–R, D, and J–K fit aids in understanding storage elements and timing circuits.
Given Data / Assumptions:
Concept / Approach:A bistable multivibrator has two stable states and remains in either until an input command causes a transition. This is exactly what flip-flops do: they store one bit of information (Q = 0 or Q = 1) until clocked or commanded to change. Astable multivibrators have no stable state and oscillate freely (e.g., RC oscillators); monostable multivibrators have one stable state and require a trigger to produce a single pulse returning to the stable state (one-shots).
Step-by-Step Solution:
Identify the number of stable states of flip-flops: two (0 and 1).Match to class definitions: two stable states → bistable.Exclude others: astable (0 stable states), monostable (1 stable state).Therefore, S–R, D, and J–K flip-flops are bistable multivibrators.Verification / Alternative check:Any flip-flop datasheet or text defines them as bistable storage elements. Timing diagrams show persistence in the current state absent a triggering event.
Why Other Options Are Wrong:Astable: oscillators, not memory elements.
Monostable: one-shot pulse generators, not two-state storage.
Tristable: not a standard multivibrator class; “tri-state” refers to outputs with a high-impedance third state, not device stability.
Common Pitfalls:Confusing “tri-state outputs” (bus drivers) with “multivibrator stability classes.” Flip-flops can have tri-stated outputs yet remain bistable devices.
Final Answer:Bistable multivibrators
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