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List of binary codes

(Redirected from Five-bit character code)

This is a list of some binary codes that are (or have been) used to represent text as a sequence of binary digits "0" and "1". Fixed-width binary codes use a set number of bits to represent each character in the text, while in variable-width binary codes, the number of bits may vary from character to character.

Five-bit binary codes

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Several different five-bit codes were used for early punched tape systems.

Five bits per character only allows for 32 different characters, so many of the five-bit codes used two sets of characters per value referred to as FIGS (figures) and LTRS (letters), and reserved two characters to switch between these sets. This effectively allowed the use of 60 characters.

Standard five-bit standard codes are:

The following early computer systems each used its own five-bit code:

The steganographic code, commonly known as Bacon's cipher uses groups of 5 binary-valued elements to represent letters of the alphabet.

Six-bit binary codes

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Six bits per character allows 64 distinct characters to be represented.

Examples of six-bit binary codes are:

See also: Six-bit character codes

Seven-bit binary codes

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Examples of seven-bit binary codes are:

Eight-bit binary codes

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10-bit binary codes

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  • AUTOSPEC – Also known as Bauer code. AUTOSPEC repeats a five-bit character twice, but if the character has odd parity, the repetition is inverted.[4]
  • Decabit – A datagram of electronic pulses which are transmitted commonly through power lines. Decabit is mainly used in Germany and other European countries.

16-bit binary codes

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32-bit binary codes

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Variable-length binary codes

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  • UTF-8 – Encodes characters in a way that is mostly compatible with ASCII but can also encode the full repertoire of Unicode characters with sequences of up to four 8-bit bytes.
  • UTF-16 – Extends UCS-2 to cover the whole of Unicode with sequences of one or two 16-bit elements
  • GB 18030 – A full-Unicode variable-length code designed for compatibility with older Chinese multibyte encodings
  • Huffman coding – A technique for expressing more common characters using shorter bit strings than are used for less common characters

Data compression systems such as Lempel–Ziv–Welch can compress arbitrary binary data. They are therefore not binary codes themselves but may be applied to binary codes to reduce storage needs.

Other

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  • Morse code is a variable-length telegraphy code, which traditionally uses a series of long and short pulses to encode characters. It relies on gaps between the pulses to provide separation between letters and words, as the letter codes do not have the "prefix property". This means that Morse code is not necessarily a binary system, but in a sense may be a ternary system, with a 10 for a "dit" or a "dot", a 1110 for a dash, and a 00 for a single unit of separation. Morse code can be represented as a binary stream by allowing each bit to represent one unit of time. Thus a "dit" or "dot" is represented as a 1 bit, while a "dah" or "dash" is represented as three consecutive 1 bits. Spaces between symbols, letters, and words are represented as one, three, or seven consecutive 0 bits. For example, "NO U" in Morse code is "— .​   — — —​       . . —", which could be represented in binary as "1110100011101110111000000010101110". If, however, Morse code is represented as a ternary system, "NO U" would be represented as "1110|10|00|1110|1110|1110|00|00|00|10|10|1110".

See also

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References

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  1. ^ a b Alan G. Hobbs (1999-03-05). "Five-unit codes". NADCOMM Museum. Archived from the original on 1999-11-04.
  2. ^ a b Gil Smith (2001). "Teletypewriter Communication Codes" (PDF).
  3. ^ "Paper Tape Readers & Punches". The Ferranti Orion Web Site. Archived from the original on 2011-07-21.
  4. ^ a b c d "Telecipher Devices". John Savard's Home Page.
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