3. Character Set

People enter data into a computer by means of an input device such as a keyboard. But actually a keyboard is simply a set of switches arranged in a certain way for your convenience. Every key is physically identical - there is no 'letter A' key or 'letter X' key.

What happens is that the keyboard sends a signal to the computer that effectively says 'The third key on the middle row has been pressed'. This 'signal' is a binary number.

The computer then has to work out what this actually means (by the way the third key in the middle row represents the letter 's' on my UK english keyboard).

So there has to be a translation between the 'third key signal' and what needs to appear on the screen. This is the job of the 'character set'.

A character set converts a binary number / code into a written language character.

For example, if you use an European language keyboard then the "Latin Alphabet No 1" character set may be installed on the computer to translate the keys into the right language symbols for you (there are other character sets that would also do the same job).

A completely different language such as Japanese would use a different character set and of course the middle-row third key would have a different symbol on it.

Do not confuse character set with font. They are not the same thing. A font will display the letter 'A' in a certain way - but it is still the letter A no matter how fancy the font!

It is the character set that maps a binary code to the the letter A. Whatever font you have selected will then display it in certain way.

So far, we have discussed 1 byte character sets such as ASCII and extended ASCII. But these can only describe 256 symbols. Some languages have far more than this. For instance some far-east languages have more than 12,000 characters!

So the logical way of handling the problem is to use a character set that uses more than 8 bits (1 byte). The next page describes multi-byte methods.