Inverter logic behavior For a NOT gate (inverter) operating with standard positive logic, under what input condition is the output HIGH?

Introduction / Context:
An inverter, or NOT gate, is the simplest logic element that performs logical negation. Mastering its truth table is essential, as inverters appear in virtually every digital design, from simple combinational networks to complex synchronous systems.

Given Data / Assumptions:

• Standard positive logic: HIGH means logical 1, LOW means logical 0.
• Ideal logic levels and no undefined states considered.
• Single-input device; there are not multiple inputs on a NOT gate.

Concept / Approach:

The inverter outputs the logical complement of its input. This is captured by the Boolean expression Y = NOT(A). Therefore, when the input is LOW (0), the output must be HIGH (1), and when the input is HIGH (1), the output must be LOW (0).

Step-by-Step Solution:

Verification / Alternative check:

Truth tables in any digital logic reference confirm that the only time the NOT gate outputs HIGH is when the input is LOW. Gate-level simulations likewise show perfect inversion in the absence of timing hazards.

Why Other Options Are Wrong:

• Input HIGH yields output LOW, not HIGH.
• Input transitions do not inherently force a specific steady-state output; the logic level at the moment determines the output.
• Removing supply voltage disables the gate, not a valid logic operation.
• Both inputs LOW does not apply; a NOT gate has only one input.

Common Pitfalls:

• Confusing NOT with buffer. A buffer outputs the same level; a NOT inverts it.
• Mixing active-low conventions. In active-low signal naming, bubbles indicate inversion; always check schematics carefully.

Final Answer:

the input is LOW