## Logic Gates – The Gateways to Intelligence in Machines

written by: Ricky • edited by: Lamar Stonecypher • updated: 8/7/2008

We often use logic and common sense in making our day to day decisions. But can the same be said about machines? Well I do not know about common sense, but certainly electronic machines can make logical decisions. Find out the science behind it.

• slide 1 of 5

### Introduction

When I am talking of making logical decisions, I do not mean complicated decisions for the time being but simple decisions. Take for example the simple logic that if you have upset stomach, you should eat a banana. Since machines do not eat or deal with bananas, it is all done in the form of binary mathematics which is the basis for all digital electronics.

• slide 2 of 5

### The Gateways of Logic

Logic gates are electronic circuits which make logical decisions based on certain inputs and give a certain output. The feature of a logical gate is that it can have multiple inputs but only and only one output. Since all science has a theoretical basis on which the practical applications and machinery is developed, the science behind logic gates is known as Boolean algebra named after its developer George Boole. We will discuss about Boolean algebra in a separate article but for now we will concentrate on its application to electronic circuitry namely the logic gates.

• slide 3 of 5

### 0 & 1

We know that I normal counting we use the decimal system which has 10 digits from 0 to 9. But there are only two digits in Boolean algebra namely 0 and 1. You might feel bit odd as to how do we represent all numbers using two digits but let me tell you that it is only a matter of getting used to any number system. Computers and digital electronic equipment are used to the binary number system. The reason for that is that actually we think of computers and other electronic equipment as very intelligent they are really quite dumb. They can only think about two things – 0 and 1. Of course there is another science known as artificial intelligence but that is not the main topic of discussion here so will leave that aside for now.

• slide 4 of 5

### Types of Gates

Gates can be studied from two perspectives namely the functions that they perform and the internal workings of the electronic circuitry which makes them perform those functions successfully. Of course we will not touch upon the latter for it is complicated electronics but the former will be studied in separate articles. As for now you must know what types of gates are there. Some of the important types of gates are OR, NOR, NOT and so forth. Each of these gates has their specific patterns of output based on their inputs and we will discuss about the working of these gates in a different article.

• slide 5 of 5

### The Truth Table

Do you know what a truth table stands for? Well if you stand on top of a table and speak the truth it can be said to be a truth table. But in the electrical parlance a truth table for a logic gate is a tabular description of the various possible outputs based on all possible combinations of inputs to that logic gate. They speak only the truth and nothing but the truth about the performance of the logic gate under all possible inputs it will encounter.