74xx logic device behavior — 7474 input types: The 7474 is a dual D-type positive-edge-triggered flip-flop. It presents two distinct classes of inputs: synchronous inputs (D, CLK) that act on the active clock edge, and asynchronous inputs (PRE, CLR) that override the state regardless of clock. Evaluate the statement.

Introduction / Context:
The 7474 is a classic TTL dual D-type flip-flop used widely in introductory and intermediate digital design. Understanding which pins are synchronous (sampled on clock edge) versus asynchronous (override regardless of clock) is essential for reliable reset/initialize logic and timing analysis.

Given Data / Assumptions:

• Device: 7474 dual D-type edge-triggered flip-flop.
• Synchronous inputs: D, CLK (state update occurs on clock edge).
• Asynchronous inputs: PRE (preset) and CLR (clear), typically active-low.
• Positive-edge triggering unless otherwise specified by variant.

Concept / Approach:
State changes from the data path occur only at the designated clock edge (synchronous). However, preset and clear are designed to force Q to 1 (PRE) or 0 (CLR) at any time they are asserted (asynchronous), independent of D or the clock. This division is explicit in datasheets and timing diagrams.

Step-by-Step Solution:

Verification / Alternative check:
Examine timing: asynchronous inputs show no setup/hold relative to clock for their primary function, while D requires setup/hold around the active edge. This difference verifies two classes of inputs.

Why Other Options Are Wrong:

• Incorrect / Only asynchronous: Contradicted by edge-triggered data path.
• Behavior depends on supply voltage only: Power affects limits, not input class.
• Applies only to latches: The 7474 is a flip-flop, not a level-sensitive latch.

Common Pitfalls:
Driving PRE and CLR simultaneously; forgetting they are usually active-low; violating D setup/hold and mislabeling timing problems as asynchronous faults.

Final Answer:
Correct