Character Encoding - History

History

Common examples of character encoding systems include Morse code, the Baudot code, the American Standard Code for Information Interchange (ASCII) and Unicode.

Morse code was introduced in the 1840s and is used to encode each letter of the Latin alphabet, each Arabic numeral, and some other characters via a series of long and short presses of a telegraph key. Representations of characters encoded using Morse code varied in length.

The Baudot code 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. 2 (ITA2) in 1930.

ASCII was introduced in 1963 and is a 7-bit encoding scheme used to encode letters, numerals, symbols, and device control codes as fixed-length codes using integers.

IBM's Extended Binary Coded Decimal Interchange Code (usually abbreviated EBCDIC) is an 8-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. The need to support more writing systems for different languages, including the CJK family of East Asian scripts, required support for a far larger number of characters and demanded a systematic approach to character encoding rather than the previous ad hoc approaches.

Early binary repertoires include:

• Bacon's cipher
• Braille
• International maritime signal flags
• Chinese telegraph code (Hans Schjellerup, 1869, modified 1872 and following)

  Encoding of Chinese characters as 4-digit decimals.