# History of bits and bytes in computer science

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I start the story by talking about base-10 system. When you understand the base-10 system, our story will not be interrupted and confused.

Okay, the base-10 system is the most popular one but it's not unique. Many cultures used different systems in the past, however, today most of them have moved to base-10 system. The base-10 system uses 10 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, which are put together to form another number.

If you only have one box, you can only write a number from 0 to 9. But ..

- If you have two boxes, you can write a number from 0 to 99.
- If you have three boxes, you can write a number from 0 to 999.

All boxes from right to left have a factor which is in turn 10^0, 10^1, 10^2, ...

### BIT

**BIT**is short for

**Binary digIT**(information unit). A

**bit**that denotes value 0 or 1, is called the smallest unit in the computer. 0, 1 are two basic digits of base-2 system.

Let infer as base-10 system and apply it to base-2 system. If you have one box, you can write 2 numbers such as 0 and 1. If you have 2 boxes, you can write 4 numbers such as

**00**,**01**,**10**, and**11**(Note: Do not be mistaken, these numbers are ones of base-2 system).
For base-2 system, the boxes from right to left have 1 factor. They are in turn 2^0, 2^1, 2^2, ...

The following image describes the way how to convert a number of base-2 system to base-10 system.

Thus:

- If you have two boxes in the base-2 system, you can write the largest number of 11 (base-2), which is equivalent to 3 in the base-10 system.
- If you have 3 boxes in base-2 system, you can write the largest number of 111 (base-2), which is equivalent to 7 in base -10 system.

Box Numbers |
Maximum Number (Base-2) |
Convert to Base-10 |

1 | 1 | 1 (2^1 - 1) |

2 | 11 | 3 (2^2 - 1) |

3 | 111 | 7 (2^3 - 1) |

4 | 1111 | 15 (2^4 - 1) |

5 | 11111 | 31 (2^5 - 1) |

6 | 111111 | 63 (2^6 - 1) |

7 | 1111111 | 127 (2^7 - 1) |

8 | 11111111 | 255 (2^8 - 1) |

9 | 111111111 | 511 (2^9 - 1) |

### Why does the computer use base-2 system but not base-10 system?

You surely ask the question "

*". I have asked this question before, like you.***Why does computer use base-2 system but not base-10 system?**
Computers operate by using millions of electronic switches (transistors), each of which is either on or off (similar to a light switch, but much smaller). The state of the switch (either on or off) can represent binary information, such as yes or no, true or false, 1 or 0. The basic unit of information in a computer is thus the binary digit (BIT). Although computers can represent an incredible variety of information, every representation must finally be reduced to on and off states of a transistor.

Thus, the answer is that computer does not have many states to store information, therefore, it stores information based on the two states of

**ON**and**OFF**(1 and 0 respectively).Your computer hard drive also stores data on the principle of 0, 1. It includes recorders and readers. It has one or more disks, which are coated with a magnetic layer of nickel. Magnetic particles can have south-north direction or north-south direction, which are two states of magnetic particle, and it corresponds to 0 and 1.

- The reader of hard drive can realize the direction of each magnetic particle to convert it into 0 or 1 signals.
- The data to be stored on hard drive is a line of 0 or 1 signals. The recorder of hard drive relies on this signal and changes the direction of each magnetic particle accordingly. This is the principle of data storage of hard drive.

**Byte**is an unit in computer which is equivalent to 8

**bits**. Thus, a

**byte**can represent a number in range of

**0 to 255.**

### Why is 1 byte equal to 8 bit?

Your question is now

*.***"Why is 1 byte equal to 8 bits but not 10 bits?"**
At the beginning of computer age people have used

**baudot**as a basic unit, which is equivalent to 5**bits**, i.e. it can represent numbers from 0 to 31. If each number represents a character, 32 is enough to use for the uppercase letters such as A, B, ... Z, and a few more characters. It is not enough for all lowercase characters.
Immediately after, some computers use 6

**bits**to represent characters and can represent at maximum 64 characters. They are enough to use for A, B, .. Z, a, b.. Z, 0, 1, 2, .. 9 but not enough for other characters such as +,-,*, / and spaces.Thus, 6**bits**quickly become to be restricted.**ASCII**defined a

**7-bit**character set. That was

**"good enough"**for a lot of uses for a long time, and has formed the basis of most newer character sets as well (

**ISO 646**,

**ISO 8859**,

**Unicode**,

**ISO 10646**, etc.)

### ASCII sets:

**8-bit**, a little bit more than

**7-bit**which is better. It doesn't cause too large waste. The

**8-bit**is a collection of numbers between 0 and 255 and it satisfies computer designers. The concept of

**byte**was born,

**1 byte = 8 bits**.

For

**8-bit**, Designers can define other characters, including special characters in computer.**ANSI**code table was born which is inheritance of the**ASCII**code table:### ANSI Sets:

There are many character sets with a view to encoding characters in different languages. For example, Chinese, Japanese require a lot of characters, in which case people uses 2

**bytes**or 4**bytes**to define a character.