ASCII ( ), abbreviated from American Standard Code for Information Interchange, is a character-encoding scheme (the IANA prefers the name US-ASCII〔). ASCII codes represent text in computers, communications equipment, and other devices that use text. Most modern character-encoding schemes are based on ASCII, though they support many additional characters. ASCII was the most common character encoding on the World Wide Web until December 2007, when it was surpassed by UTF-8, which includes ASCII as a subset.
ASCII developed from telegraphic codes. Its first commercial use was as a seven-bit teleprinter code promoted by Bell data services. Work on the ASCII standard began on 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 during 1963, underwent a major revision during 1967, and experienced its most recent update during 1986. Compared to earlier telegraph codes, the proposed Bell code and ASCII were both ordered for more convenient sorting (i.e., alphabetization) of lists, and added features for devices other than teleprinters.
Originally based on the English alphabet, ASCII encodes 128 specified characters into seven-bit binary integers as shown by the ASCII chart on the right. The characters encoded are numbers ''0'' to ''9'', lowercase letters ''a'' to ''z'', uppercase letters ''A'' to ''Z'', basic punctuation symbols, control codes that originated with Teletype machines, and a space. For example, lowercase ''j'' would become binary 1101010 and decimal 106. ASCII includes definitions for 128 characters: 33 are non-printing control characters (many now obsolete) that affect how text and space are processed〔International Organization for Standardization (December 1, 1975). "(The set of control characters for ISO 646 )". ''Internet Assigned Numbers Authority Registry''. Alternate U.S. version: (). Accessed 2008-04-14.〕 and 95 printable characters, including the space (which is considered an invisible graphic〔("RFC 20: ASCII format for Network Interchange" ), ANSI X3.4-1968, October 16, 1969.〕).
The American Standard Code for Information Interchange (ASCII) was developed under the auspices of a committee of the American Standards Association (ASA), called the X3 committee, by its X3.2 (later X3L2) subcommittee, and later by that subcommittee's X3.2.4 working group. The ASA became the United States of America Standards Institute or USASI〔 and ultimately the American National Standards Institute.
抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』
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