NOT

Inputs

Outputs

How It Works

The inverter is the simplest gate: one input and one job — say the opposite. In real life it is a "reversed" switch: when the room light is on, the "busy" sign glows; when the light is off, the sign goes dark. NOT always states the opposite of what it sees at the input.

The key property of NOT: it turns 0 into 1 and 1 into 0 — and nothing else. Example: a sensor outputs "door closed", but your indicator needs "door open" — one inverter solves the problem. It is also useful to know the reverse: two NOT gates in a row return the original signal, NOT(NOT(x)) = x — a double negation.

A nuance worth remembering: NOT is a NAND with joined inputs. NAND(A,A) outputs 0 only when A=1, which is exactly an inverter's behavior. That is how you build it in the game at Level 2, and that is why NOT is the "cheapest" gate — half of a NAND is enough.

Truth Table and Examples

Example of meaning inversion: a sensor outputs 1 when the door is closed. The "Open" lamp must light at 0 — put a NOT between the sensor and the lamp, and the logic matches without rebuilding the sensor. Another example: a "no error" signal (1) inverts into "error" (0) for an alarm line.

Usage

NOT is unlocked at Level 2 as the first standalone build from NAND — and it never leaves the palette. It turns NAND back into AND, builds OR via De Morgan, and paired with NAND produces any other gate. The bus analog BusNOT inverts all 8 bits of a byte at once.

Concrete roles: reset lines where the active level is zero (reset = 0), inverting status flags ("not zero" from "zero"), and turning an "equals" check into a "not equals" check. No decoder works without inverters: to select one address out of many, every "foreign" bit must be negated.

Interactive Demo

Click inputs to toggle value (0 / 1)