3. ASCII continued

In ASCII every character (glyph) is represented by a binary number, e.g:

.

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

The 8 bit ASCII code below represents the lower case letter a:

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

01001010 01001111 01001000 01001110

The word JOHN would take 4 bytes of memory to store (1 byte per character).

Since computer architecture is built around the byte (which has 8 bits) the 7-bit ASCII table is a little inconvenient.

So ASCII standard characters are padded out to 8 bits, with the leftmost bit set to 0.

There is, however, an extension to ASCII, called "Extended ASCII", that makes another use of this spare digit to fit in another 128 characters commonly used in other languages.