ASCII vs Unicode

By Tanaka

How binary is used to represent characters

In ASCII every character is represented by a binary number.

The 8 bit ASCII code below represents the upper case letter A:

0110 0001

If you wanted to represent the word JOHN in ASCII, it would look like this:

01001010 01001111 01001000 01001110

Notice that the highest bit is zero in the examples shown above. This means that standard ASCII only uses the first 128 numbers available out of a possible 256.

Character set

The ASCII character set defines 128 characters. This character set is a subset of many other character sets with 256 characters.The character set names may be up to 40 characters taken from theprintable characters of US-ASCII. However, no analysis, is made between use of upper and lower case letters.