NOR versus OR – do they operate in exactly the same way?
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ACorrect
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BIncorrect
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COnly with wired-OR lines
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DOnly when inputs are all LOW
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EOnly with tri-state outputs
Answer
Correct Answer: Incorrect
Explanation
Introduction / Context: OR and NOR are related but distinct logic operations. Recognizing the inversion bubble on NOR is vital for correct reading of schematics and active-LOW signal conventions.
Given Data / Assumptions:
- Standard two-input (extendable to N input) gates.
- Active-HIGH logic convention.
- Ideal Boolean behavior.
Concept / Approach: NOR is the logical negation of OR: NOR(A,B) = NOT(OR(A,B)). Their truth tables are complements. Therefore, they do not operate in the same way; NOR only outputs 1 when all inputs are 0, while OR outputs 1 if any input is 1.
Step-by-Step Solution:
1) OR truth: any input HIGH → output HIGH.2) NOR truth: any input HIGH → output LOW; only all LOW → output HIGH.3) Since outputs differ for all input combinations except the all-LOW case's complement, they are not identical functions.4) Conclusion: the statement is incorrect.Verification / Alternative check: Draw symbols: NOR shows an inversion bubble at the output, signaling logical negation. Truth tables confirm complementarity. De Morgan's laws also express relationships: NOR equals AND of inverted inputs: NOR(A,B) = NOT(A + B) = (NOT A) * (NOT B).
Why Other Options Are Wrong: “Correct” is false by definition. “Only with wired-OR lines” and “Only with tri-state outputs” confuse hardware interconnects with logical functions. “Only when inputs are all LOW” cherry-picks a single row and ignores other combinations.
Common Pitfalls: Ignoring inversion bubbles in schematic symbols; that bubble changes the function dramatically. Always check polarity indicators.
Final Answer: Incorrect