Binary and data representation - EdexcelCharacters
All data in a computer is represented in binary, whether it is numbers, text, images or sound. The computer software processes the data according to its content.
Computers can only recognise binaryA number system that contains two symbols, 0 and 1. Also known as base 2.. As a result, all characters - whether they are letters, punctuation or numbers - are stored as binary numbers. All of the characters that a computer can use are called a character setA table of data that links a character to a number. This allows the computer system to convert text into binary. Examples are ASCII and Unicode. .
One of the standards in common use is the ASCIIAmerican Standard Code for Information Interchange. A 7-bit character set used for representing English keyboard characters.
How computers encode characters using 7-bit ASCII
ASCII uses seven bitThe smallest unit of data in computing represented by a 1 in binary., giving a character set of 128 characters. The characters are represented in a table, called the ASCII table. The 128 characters include:
32 control codes - mainly to do with printing
32 punctuation codes, symbols, and space
26 upper case letters
26 lower case letters
numeric digits 0-9
In ASCII, each character has its own assigned number. For example:
Character
Denary
Binary
Hexadecimal
A
65
1000001
41
Z
90
1011010
5A
a
97
1100001
61
z
122
1111010
7A
0
48
0110000
30
9
57
0111001
39
Space
32
0100000
20
!
33
0100001
21
Character
A
Denary
65
Binary
1000001
Hexadecimal
41
Character
Z
Denary
90
Binary
1011010
Hexadecimal
5A
Character
a
Denary
97
Binary
1100001
Hexadecimal
61
Character
z
Denary
122
Binary
1111010
Hexadecimal
7A
Character
0
Denary
48
Binary
0110000
Hexadecimal
30
Character
9
Denary
57
Binary
0111001
Hexadecimal
39
Character
Space
Denary
32
Binary
0100000
Hexadecimal
20
Character
!
Denary
33
Binary
0100001
Hexadecimal
21
When data is stored or transmitted, it is its ASCII number that is used to represent the character.
For example, the word ‘Computer’ would be represented as:
Extended ASCII uses eight bits, giving a character set of 256 characters. This allows for special characters such as those with accents in languages such as French and Spanish.
