Ascii, Ascii

ASCII codes represent text in computers, communications equipment, and other devices that work with text. Most modern character-encoding schemeswhich support many more characters than did the originalhave a historical basis in ASCII.

Work on ASCII formally began October 6, 1960, with the first meeting of the American Standards Association's (ASA) X3.2 subcommittee. The first edition of the standard was published in 1963, Mary Brandel (July 6, 1999).

The most commonly used character encoding on the World Wide Web was US-ASCII until 2008, when it was surpassed by UTF-8.

To include all these, and control characters compatible with the Comit Consultatif International Tlphonique et Tlgraphique standard, Fieldata, and early EBCDIC, more than 64 codes were required in ASCII.

The standards committee decided against shifting, and so ASCII required at least a seven-bit code. Decision 4. Mackenzie, p.215.

Almost every country needed an adapted version of ASCII since ASCII only suited the needs of the USA and a few other countries. For example, Canada had its own version that supported French characters. Other adapted encodings include ISCII (India), VISCII (Vietnam), and YUSCII (Yugoslavia). Although these encodings are sometimes referred to as ASCII, true ASCII is strictly defined only by ANSI standard.

This allows UTF-8 to be backward compatible with ASCII, a significant advantage.

Paper tape was a very popular medium for long-term program storage up through the 1980s, lower cost and in some ways less fragile than magnetic tape. In particular, the Teletype 33 machine assignments for codes 17 (Control-Q, DC1, also known as XON), 19 (Control-S, DC3, also known as XOFF), and 127 became de facto standards. Because the keytop for the O key also showed a left-arrow symbol (from ASCII-1963, which had this character instead of underscore), a noncompliant use of code 15 (Control-O, Shift In) interpreted as "delete previous character" was also adopted by many early timesharing systems but eventually faded out.

Marchal, ISO/TC 97 - Computers and Information Processing: Acceptance of Draft ISO Recommendation No. 1052, December 22, 1967 caused ASCII's choices for the national use characters to appear to be de facto standards for the world, leading to confusion and incompatibility once other countries did begin to make their own assignments to these code points.

Still, ISO-8859-1 , its variant Windows-1252 (often mislabeled as ISO-8859-1), and the original 7-bit ASCII remain the most common character encodings in use today.

Source: Wikipedia > Ascii