When a system defines a HIGH voltage as binary 0 and a LOW voltage as binary 1, what is this logic convention called?
-
Anegative logic
-
Bpositive logic
-
Cinvalid logic
-
Dassertion-level logic
Answer
Correct Answer: negative logic
Explanation
Introduction:Logic conventions determine how physical voltages map to logical values. Two common conventions are positive logic and negative logic, which invert the mapping relative to each other.
Given Data / Assumptions:
- HIGH voltage is assigned to binary 0.
- LOW voltage is assigned to binary 1.
- We are asked to name this convention.
Concept / Approach:In positive logic, HIGH corresponds to 1 and LOW to 0. In negative logic, the mapping is reversed: HIGH corresponds to 0 and LOW corresponds to 1. Therefore, the described mapping is negative logic.
Step-by-Step Solution:
Identify mapping: HIGH -> 0, LOW -> 1.Compare with definitions: positive vs negative logic.Recognize inversion relative to positive logic.Select “negative logic.”Verification / Alternative check:Truth tables under negative logic can be transformed to positive logic by complementing signals and reinterpretation; functional behavior remains consistent when conventions are applied uniformly.
Why Other Options Are Wrong:
- Positive logic: Opposite mapping (HIGH = 1).
- Invalid logic: The convention is valid; it is a defined alternative.
- Assertion-level logic: Refers to active-high or active-low signaling semantics, not the global numeric mapping itself.
Common Pitfalls:Assuming negative logic is “wrong.” It is legitimate and often used in active-low control signals (e.g., enable_n).
Final Answer:negative logic