- What are NOR Gates.
- How the truth table and timing Diagram of NOR Gate looks like.
- Why NOR is called universal Gate.
- How to derive other Gates through NOR Gate in Proteus ISIS.
- What are the Advantages of NOR Gate.

### NOR Gate

As the name implies, a NOR gate is a combinational Gate and we introduce it as: "**NOR gate**is the OR Gate followed by the NOT Gate and it give the output

**HIGH**only when both the inputs are

**LOW**." OR Gate has minimum two inputs and only one output. Assume that

**A**and

**B**are the inputs of NOR Gate then the Output Y is denoted by a plus sign between inputs and a collective bar or complement sign on the statement as:

Graphically, when we show a NOR Gate, we make a bubble at the start of output of OR Gate. This bubble shows the inversion of the OR gate. We can use both the graphical symbols while using the NOR Gate but usually, we prefer the right symbol as it is less complicated and more demonstrative.

Y=(A.B)'

### Truth Table and Timing diagram of NOR Gate

In the world of Logic Circuits, we often use a term truth table. A Truth Table is tabular representation of a gate and we use the following statement to define Truth Table:Hence the Truth table of NOR Gate contain its inputs as well as the output and it looks as following :"A Truth Table is a mathematical way to built a table that contain the input and the output of a mathematical Problem or Logic Design in it."

A |
B |
(A+B)’ |

0 | 0 | 1 |

0 | 1 | 0 |

1 | 0 | 0 |

1 | 1 | 0 |

### NOR as Universal Gate

Recall that Universal Gates are the one that have the characteristic to be used as other types of gates when designed specifically. There are two Universal Gates NAND Gate and NOR Gate. We call the NOR Gate as Universal Gate because we can design the other Logic Gates using the NOR Gate. NOR Gate can be used as:- NOR Gate
- OR Gate
- NOT Gate
- AND Gate

## NOR as Universal Gate in Proteus ISIS

While Designing the circuits, we need the following Components:### Material Required

- NOR Gate
- Logic Toggle
- LED
- Ground Terminal
- Connecting Wires

### NOT Gate

While designing a NOT Gate through NOR Gate we must follow the statement:Mathematically,"We get a inverse of the Input A, when we OR the input with it self and take the Compliments of it."

(A.A)'=A'

- Take a NOR Gate from the Pick Library.
- Fix it at the working sheet.
- Join both the inputs through wires.
- Attach Logic Toggle for the Input.
- Attach LED with Ground terminal and connect them to output so we can notice the output.

- Observe the lightening of LED while the input is 0.
- Change the Logic Toggle to 1 and observe output.

### OR Gate

During the formation of OR Gate through NOR Gate, we have to keep in mind the following statement:We denote this Statement as:"The output of NORed inputs is also the ORed input."

**(A.B)'=A+B**

- Take two NOR Gates.
- Connect the second NOR Gate's inputs with each other.
- Join the output of first one with the output of the other.
- Join grounded LED and Logic Probes for input and output respectively.
- Pop the play button.

### AND Gate

The core statement of the formation of AND Gate through NOR is given next:"The NORed output of Complements of the input is AND Gate."Mathematically,

(A'+B')'=AB

- Get the two NOR Gates from Pick Library.
- Fix them vertically at the working sheet.
- Connect the input of each of them with themselves.
- Join Logic Toggle with each of it.
- Take another NOR Gate from the pick Library.
- Connect the output of 1st two with the input of the third.
- Get the Grounded LED and fix it at the remaining output.

- Press the Play sign of the Proteus ISIS.
- Design the Truth Table by applying the required inputs.

### Advantages

- It occupies little space.
- It is less expensive.
- we can use it in the place of four Gates.
- It is less complex.