Using XOR as a controlled inverter: An exclusive-OR gate will invert the signal on one input if the other input is held permanently HIGH. Is this behavior correct?

Introduction / Context:
The exclusive-OR (XOR) gate is a versatile building block. One practical use is as a conditional inverter: by tying one input to a control level, the XOR either passes the signal through unchanged or inverts it. This capability appears frequently in digital signal conditioning and simple arithmetic circuits.

Given Data / Assumptions:

• Two-input XOR gate under positive logic.
• One input is held at logic HIGH (1).
• The other input is the signal of interest.

Concept / Approach:
The XOR truth rule is A XOR B = 1 when A ≠ B and 0 when A = B. If one input is fixed at 1, the output becomes the logical NOT of the other input because output is 1 exactly when the other input is 0, and 0 when it is 1. Thus, tying an XOR input high converts the gate into an inverter for the remaining input.

Step-by-Step Solution:

Verification / Alternative check:
Similarly, if the control input C = 0, XOR passes the signal through (Y = S). This dual behavior allows simple “invert enable” functions in designs without adding a separate NOT gate.

Why Other Options Are Wrong:

• Incorrect/conditional options: The XOR identity holds across logic families and frequencies within normal operating limits; it is a fundamental truth-table property, not a timing artifact.

Common Pitfalls:
Confusing XOR with OR (where tying one input HIGH forces constant HIGH); forgetting that XOR with 1 toggles, with 0 passes-through.

Final Answer:
Correct