Logic Gates:
Logic gates are basic building blocks of digital circuits that perform logical operations on one or more binary inputs to produce a single binary output. They are fundamental to digital electronics and are used in computing systems, controllers, and other electronic devices.
1. AND Gate:
The AND gate outputs a 1 (true) only if both inputs are 1; otherwise, the output is 0 (false).
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Symbol:
The symbol is a flat-ended shape with two inputs on the left and one output on the right. -
Truth Table:
| A (Input) | B (Input) | Output (A AND B) |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 1 |
2. OR Gate:
The OR gate outputs a 1 if at least one input is 1.
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Symbol:
The symbol is curved on the input side, with two inputs on the left and one output on the right. -
Truth Table:
| A (Input) | B (Input) | Output (A OR B) |
|---|---|---|
| 0 | 0 | 0 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 1 |
3. NOT Gate:
The NOT gate is a unary gate (it has only one input) that inverts the input. If the input is 1, the output is 0, and vice versa.
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Symbol:
The symbol is a triangle with a small circle (representing inversion) at the output. -
Truth Table:
| A (Input) | Output (NOT A) |
|---|---|
| 0 | 1 |
| 1 | 0 |
4. NAND Gate:
The NAND gate is the opposite (negation) of the AND gate. It outputs 0 only if both inputs are 1; otherwise, it outputs 1.
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Symbol:
The NAND gate symbol is the same as the AND gate but with a small circle (negation) at the output. -
Truth Table:
| A (Input) | B (Input) | Output (A NAND B) |
|---|---|---|
| 0 | 0 | 1 |
| 0 | 1 | 1 |
| 1 | 0 | 1 |
| 1 | 1 | 0 |
5. NOR Gate:
The NOR gate is the opposite (negation) of the OR gate. It outputs 1 only if both inputs are 0; otherwise, it outputs 0.
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Symbol:
The NOR gate symbol is the same as the OR gate but with a small circle (negation) at the output. -
Truth Table:
| A (Input) | B (Input) | Output (A NOR B) |
|---|---|---|
| 0 | 0 | 1 |
| 0 | 1 | 0 |
| 1 | 0 | 0 |
| 1 | 1 | 0 |
Summary of Symbols:
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AND:
- Symbol: ⦁
- Truth Table: 1 when both inputs are 1.
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OR:
- Symbol: ⊕
- Truth Table: 1 when at least one input is 1.
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NOT:
- Symbol: ⊖
- Truth Table: Inverts the input.
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NAND:
- Symbol: ⦁ with a circle.
- Truth Table: Negation of AND.
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NOR:
- Symbol: ⊕ with a circle.
- Truth Table: Negation of OR.