Question

Which circuit produces output only based on current inputs without memory?

• A. Sequential circuit
• B. Combinational circuit
• C. Register circuit
• D. Flip-flop circuit

Hint:

Standard building blocks like Half Adders, Full Adders, Multiplexers, and Decoders are all examples of combinational circuits.

Answer 1

The Correct Option is B

Concept: Digital circuits are partitioned based on whether they can "remember" previous states or if they process information instantaneously.
• Combinational Logic: Output = $f(\text{Present Inputs})$.
• Sequential Logic: Output = $f(\text{Present Inputs, Past State})$.

Step 1: Understanding Combinational Logic.
In a combinational circuit, the output changes as soon as the inputs change (after a small propagation delay). There is no feedback loop, so the circuit "forgets" everything once the inputs are removed.

Step 2: Analyzing the other options.
Sequential circuits (A), Registers (C), and Flip-flops (D) all use memory elements. They require a clock signal to synchronize the transition of stored states.

Step 3: Final Identification.
Since the question specifies "without memory," the answer must be Combinational.