The earliest well-known electrically-transmitted character code, Morse code, introduced in the 1840s, used a system of four "symbols" (short signal, long signal, short space, long space) to generate codes of variable length.
The earliest codes were based upon manual and hand-written encoding and cyphering systems, such as Bacon's cipher, Braille, International maritime signal flags, and the 4-digit encoding of Chinese characters for a Chinese telegraph code (Hans Schjellerup, 1869).
Unicode, a well defined and extensible encoding system, has supplanted most earlier character encodings, but the path of code development to the present is fairly well known. The Baudot code, a five-bit encoding, was created by Émile Baudot in 1870, patented in 1874, modified by Donald Murray in 1901, and standardized by CCITT as International Telegraph Alphabet No.
Unicode, a well defined and extensible encoding system, has supplanted most earlier character encodings, but the path of code development to the present is fairly well known. The Baudot code, a five-bit encoding, was created by Émile Baudot in 1870, patented in 1874, modified by Donald Murray in 1901, and standardized by CCITT as International Telegraph Alphabet No.
Unicode, a well defined and extensible encoding system, has supplanted most earlier character encodings, but the path of code development to the present is fairly well known. The Baudot code, a five-bit encoding, was created by Émile Baudot in 1870, patented in 1874, modified by Donald Murray in 1901, and standardized by CCITT as International Telegraph Alphabet No.
ASCII67's American-centric nature was somewhat addressed in the European ECMA-6 standard. Somewhat historically isolated, IBM's Binary Coded Decimal (BCD) was a six-bit encoding scheme used by IBM in as early as 1959 in its 1401 and 1620 computers, and in its 7000 Series (for example, 704, 7040, 709 and 7090 computers), as well as in associated peripherals.
In 1963 the first ASCII (American Standard Code for Information Interchange) code was released (X3.4-1963) by the ASCII committee (which contained at least one member of the Fieldata committee, W.
IBM's Extended Binary Coded Decimal Interchange Code (usually abbreviated as EBCDIC) is an eight-bit encoding scheme developed in 1963. The limitations of such sets soon became apparent, and a number of ad hoc methods were developed to extend them.
ASCII63 was a success, widely adopted by industry, and with the follow-up issue of the 1967 ASCII code (which added lower-case letters and fixed some "control code" issues) ASCII67 was adopted fairly widely.
In 1985, the average personal computer user's [disk drive] could store only about 10 megabytes, and it cost approximately US$250 on the wholesale market (and much higher if purchased separately at retail), so it was very important at the time to make every bit count. The compromise solution that was eventually found and developed into Unicode was to break the assumption (dating back to telegraph codes) that each character should always directly correspond to a particular sequence of bits.
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