NOR gate is one of the **universal logic gates** along with the **NAND gate**. Do you know** **how to make NOR gate? How does NOR gate work? One can make a NOR gate by connecting an **OR gate** and a **NOT gate** in series. So, the main work of a **NOR gate is to give the inverted output of an OR gate**. Before understanding these things we need to know the basic things of s NOR logic gate. In this article, we are going to discuss the **definition, circuit symbol, Boolean expression and truth table of NOR gate with two inputs and three inputs** respectively.

**Contents in this article:**

**Definition of NOR gate****Boolean expression of NOR gate****Circuit symbol of NOR gate****NOR gate with two inputs****NOR gate with 3 inputs****Truth table of NOR gate with three inputs**

**What is NOR gate?**

A NOR gate consists of an **OR gate and a NOT gate in series**. NOR gate is a logic gate that gives the output as the complement of the sum of the inputs. So, the output of a NOR gate is the complement of the output of an OR gate with the same inputs. Therefore, **NOR gate is the inverter of OR gate**.

**Boolean expression of NOR gate**

A NOR gate can have an infinite number of inputs and only one output. If **A, B, C, D**….. etc. be the inputs of a NOR gate then the **expression for the Boolean** **output** of the NOR logic is \small \textbf{Y=} \overline{\textbf{A+B+C+D}}.

**Circuit symbol for Two Input NOR gate**

This is the circuit symbol of NOR gate with 2 inputs **A** and **B**. Here, **Y** is the output. NOR gate consists of an OR gate and a NOT gate. The bubble at the head of the symbol comes from the NOT gate and the rest are from the OR gate.

**Truth Table for Two Input NOR gate**

Here is the truth table for a NOR gate with two inputs **A** and **B**. **Y** represents the output of the gate.

Input (A) | Input (B) | Output \small \textbf{Y=} \overline{\textbf{A+B}} |

0 | 0 | 1 |

0 | 1 | 0 |

1 | 0 | 0 |

1 | 1 | 0 |

**Truth Table of NOR gate with two inputs**

**Circuit diagram NOR gate with 3 inputs**

Here is the circuit symbol of three input NOR gate with the inputs **A, B** and **C**.

**Truth Table of NOR gate with 3 inputs**

Here is the NOR gate truth table with three inputs **A, B** and **C**. It gives the inverted output of OR gate.

Input (A) | Input (B) | Input (C) | Output \small \textbf{Y=} \overline{\textbf{A+B+C}} |

0 | 0 | 0 | 1 |

0 | 0 | 1 | 0 |

0 | 1 | 0 | 0 |

0 | 1 | 1 | 0 |

1 | 0 | 0 | 0 |

1 | 0 | 1 | 0 |

1 | 1 | 0 | 0 |

1 | 1 | 1 | 0 |

**Truth Table for three input NOR gate**

**Uses of NOR logic**

- NOR gate is one of the
**universal logic gates**. So, it can be used to develop other logic gates. - NOR gate has decent applications in memory circuits.
- The main work of NOR gate is to provide the inverted output of an OR gate.

This is all from this article on **NOR gate and its truth table and circuit diagram**. If you have any doubt on this topic you can ask me in the comment section.

Thank you!

**Related posts:**

**Basic logic gates – OR, AND and NOT gate****NAND gate****XOR gate using NAND gate****XNOR gate using NAND gate****Boolean algebra****Karnaugh map (K-map)**

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