Logic level conventions — positive logic In positive-logic systems, which mapping between voltage level and logic value is used?

Introduction / Context:
Digital logic can be defined using polarity conventions. Positive logic is the most common convention in which higher voltage represents the logic TRUE state. Knowing this mapping is essential when reading datasheets, designing interfaces, or interpreting timing diagrams.

Given Data / Assumptions:

• Standard TTL/CMOS-like logic families.
• No inverted or negative-logic reinterpretations applied.

Concept / Approach:
In positive logic, a higher voltage (near Vcc) corresponds to logic 1 (TRUE), and a lower voltage (near ground) corresponds to logic 0 (FALSE). Negative logic uses the opposite mapping. The choice affects naming (active-high vs. active-low signals) but not the physical operation once interpreted consistently.

Step-by-Step Solution:

Verification / Alternative check:
Look at common signals like RESET active-high versus RESET̅ (active-low). In positive logic, asserting a signal usually means driving it HIGH to indicate logic 1.

Why Other Options Are Wrong:

• LOW = 1, HIGH = 0: Negative-logic mapping, not positive.
• Only HIGHs/Only LOWs: Illogical since both levels are required for binary logic.

Common Pitfalls:
Confusing electrical polarity with logical meaning. Always check whether a signal is active-high or active-low in schematics and code.

Final Answer:
a HIGH = 1, a LOW = 0