# what is logic gate? in DLD Digital Logic Design

Last modified on May 26th, 2018 at 2:07 pm

**LOGIC GATES**

We are familiar with basic addition and subtraction operation. There are also many other functions that digital systems are able to perform with the help of logic gates.

- Logic Gates can be used to implement large complex systems.
- Digital Logic Gates are identified by unique symbols. These symbols are used in circuit diagrams. Circuit diagram in whole define the function of a digital circuit.
- Digital Logic Gates function can be represented by the followings;\
- Boolean expression
- Truth table / Function table
- Logic circuit diagram

### What is truth table?

Truth table is a table that stores inputs values and output after performing the operation on given inputs.

### What is example of truth table?

Following table shows truth table for NOT Gate.

Input | Output |

o | 1 |

1 | o |

### What are boolean expressions?

Some symbols and operators are used to represent the given inputs and output.

### What are some examples of boolean expressions?

Operator | Meaning | Expression |

+ | OR | X+ Y |

* | AND | X AND Y |

### What is logic circuit diagram?

Logic circuit diagram is a graphical representation of given inputs and outputs.

### What is example of logic circuit diagram?

The three fundamental Gates are the AND, OR and NOT Gates and further classified as mentioned below;

- NAND
- XOR
- XNOR