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Introduction to ASCII code

ASCII stands for American Standard Code for Information Interchange and is a character encoding based on the English alphabet. The ASCII code is used to represent text in computers, and other IT devices that work with text. The code specifies a correspondence between digital bit patterns and the symbols/glyphs of English language, hence allowing digital devices to communicate with each other and to store and process information. The ASCII encoding is used on nearly all computers, especially PCs and workstations.

ASCII first appeared as a standard in 1963. It was last updated in 1986. Currently it defines 33 non-printing control characters which affect how the text is processed and 95 printable characters. The standard ASCII character code uses only 7 bits for each character and several characters use 8 bits. ASCII uses the bit patterns with seven binary digits (a range of 0 to 127 decimal) to represent characters.

DOS operating system uses superset of ASCII called extended ASCII. ASCII is not the only set of standard codes. ISO Latin 1 is used by many operating systems as well as by web browsers, while EBCDIC is used by large IBM computers.

ASCII code developed from telegraphic codes. It first entered commercial use as a seven-bit teleprinter code promoted by Bell data services. Bell previously planned to use a six-bit code but was persuaded instead to join the ASA subcommittee which started to develop ASCII. Compared to earlier telegraph codes, the ASCII code underwent re-ordering for more convenient sorting of lists and also added features for devices other than teleprinters. Later, Bob Bemer introduced new features to the code. In UK, Bemer’s colleague Hugh McGregor Ross popularized his work and the new code became known in Europe as the Bemer-Ross Code.

ASA (The American Standards Association) first published ASCII as a standard in 1963. But the first version lacked the lowercase letters, and it had an up-arrow (↑) instead of the caret (^) and a left-arrow (←) instead of the underscore (_). The new version which appeared in 1967 added the lower cases, moved ACK and ESC from the lowercase letters area into the control codes area and changed the names of a few control characters. The code was updated over the years and new versions were published in 1968, 1977 and 1986.

ASCII is now considered the most successful software standard ever developed.

Other information about ASCII code The first 32 characters (numbers 0–31 decimal) are reserved for control characters. Code 32 represents the space character (the one produced by the space-bar on the keyboard) while codes 33 to 126 (the printable characters) represent letters, punctuation marks, digits and other symbols. There are several aliases for ASCII suitable for use on the Internet: ANSI_X3.4-1968, ANSI_X3.4-1986, ASCII, US-ASCII, us, ISO646-US, ISO_646.irv:1991, iso-ir-6, IBM367, cp367 and csASCII. Many of us have probably seen the ASCII art. It’s an artistic medium that relies on computers for presentation, using the 95 printable characters pieced together to form picture. The simples ASCII art are the emoticons or smileys used in chat programs. All of us know what :-) or :-P means. There are also the “face characters”, widely used in Japan. For example (^_^) means happy. A lot time and experience can lead to a lot of nice art.

Figure 1 A dog as it's depicted in ASCII art from http://en.wikipedia.org/wiki/ASCII_art