What is a Character Set?
A character set is a set of characters where each character has a unique binary number.
This is then used so that a computer is able to recognise the different letters, symbols digits that it has to store, send, receive etc.
For example.
the letter ‘a’ is 1100001 in ASCII
the letter ‘A’ is 1000001 in ASCII
ASCII
The ASCII character set is a 7–bit set of codes that allows 128 different characters.
That is enough for every upper-case letter, lower-case letter, digit and punctuation mark in the English language.
Extended ASCII
Extended ASCII is a character set that uses an 8 bit set of codes that allows for 256 characters to be represented.
The first 128 characters are exactly the same as ASCII characters.
Extended ASCII makes use of the additional characters for European languages which such as those with accents e.g. è, ú, ó
Unicode
Since ASCII and extended ASCII can only represent a limited number of characters (can only have so many numbers with just 7 or 8 bits), they cannot be used to represent all international characters.
Unicode is the new standard for representing the characters of all of the languages of the world, such as Chinese, Arabic and Japanese characters.
This is possible because the Unicode uses 16 bit and 32 bit codes to represent characters.
How to calculate the number of characters that a character set has
If you know how many bits are used per character in a set, it is possible to work out how many different characters can be represented.
(this is the number of different combinations of 1’s and 0’s)
This is done using the following formula:
2number of bits
Therefore, the higher the number of bits used per character, the greater the number of characters that can be represented.