ASCII

• It stands for American Standard Code for Information Interchange

• ASCII is a character encoding based on the English alphabet.

• It is an ANSI (American National Standards Institute) standard

• It defines codes for 128 characters: – 33 are non-printing, mostly obsolete control characters that

affect how text is processed– 95 are printable characters

ASCII• ASCII is a seven-bit code, meaning it uses patterns of seven binary digits (a

range of 0 to 127 decimal) to represent each character.– When ASCII was introduced, many computers used eight-bit bytes as the

native data type. The eighth bit was commonly used as a parity bit for error checking on communication lines

0 1 0 0 0 0 0 1

ASCII

• Different versions of ASCII were created for different applications– Windows-1252 - Changed some of the character encodings– Mac OS Roman - Extended the encoding beyond 7 bits (the

7-bit characters were the same)

ASCII

ASCII

• The good– Encode all characters in 1 byte– Almost every computer supports/supported ASCII

• The bad– Can only encode English (with a limited number of

accented characters)