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In telecommunication, bit pairing is the practice of establishing, within a code set, a number of subsets that have an identical bit representation except for the state of a specified bit.
Note: An example of bit pairing occurs in the International Alphabet No. 5 and the American Standard Code for Information Interchange (ASCII), where the upper case letters are related to their respective lower case letters by the state of bit six.
ASCII, abbreviated from American Standard Code for Information Interchange, is a character encoding standard for electronic communication. ASCII codes represent text in computers, telecommunications equipment, and other devices. Most modern character-encoding schemes are based on ASCII, although they support many additional characters.
The Baudot code[boˈdo] is an early character encoding for telegraphy invented by Émile Baudot in the 1870s. It was the predecessor to the International Telegraph Alphabet No. 2 (ITA2), the most common teleprinter code in use until the advent of ASCII. Each character in the alphabet is represented by a series of five bits, sent over a communication channel such as a telegraph wire or a radio signal. The symbol rate measurement is known as baud, and is derived from the same name.
In computing, data storage, and data transmission, character encoding is used to represent a repertoire of characters by some kind of encoding system that assigns a number to each character for digital representation. Depending on the abstraction level and context, corresponding code points and the resulting code space may be regarded as bit patterns, octets, natural numbers, electrical pulses, or anything of the like. A character encoding is used in computation, data storage, and transmission of textual data. "Character set", "character map", "codeset" and "code page" are related, but not identical, terms.
Extended Binary Coded Decimal Interchange Code is an eight-bit character encoding used mainly on IBM mainframe and IBM midrange computer operating systems. It descended from the code used with punched cards and the corresponding six-bit binary-coded decimal code used with most of IBM's computer peripherals of the late 1950s and early 1960s. It is supported by various non-IBM platforms, such as Fujitsu-Siemens' BS2000/OSD, OS-IV, MSP, and MSP-EX, the SDS Sigma series, Unisys VS/9, Unisys MCP and ICL VME.
In mathematics and computing, the hexadecimal numeral system is a positional numeral system that represents numbers using a radix (base) of 16. Unlike the decimal system representing numbers using 10 symbols, hexadecimal uses 16 distinct symbols, most often the symbols "0"–"9" to represent values 0 to 9, and "A"–"F" to represent values from 10 to 15.
ISO/IEC 8859-1:1998, Information technology — 8-bit single-byte coded graphic character sets — Part 1: Latin alphabet No. 1, is part of the ISO/IEC 8859 series of ASCII-based standard character encodings, first edition published in 1987. ISO 8859-1 encodes what it refers to as "Latin alphabet no. 1", consisting of 191 characters from the Latin script. This character-encoding scheme is used throughout the Americas, Western Europe, Oceania, and much of Africa. It is the basis for some popular 8-bit character sets and the first two blocks of characters in Unicode.
ISO/IEC 8859 is a joint ISO and IEC series of standards for 8-bit character encodings. The series of standards consists of numbered parts, such as ISO/IEC 8859-1, ISO/IEC 8859-2, etc. There are 15 parts, excluding the abandoned ISO/IEC 8859-12. The ISO working group maintaining this series of standards has been disbanded.
UTF-16 (16-bit Unicode Transformation Format) is a character encoding capable of encoding all 1,112,064 valid character code points of Unicode (in fact this number of code points is dictated by the design of UTF-16). The encoding is variable-length, as code points are encoded with one or two 16-bit code units. UTF-16 arose from an earlier obsolete fixed-width 16-bit encoding, now known as UCS-2 (for 2-byte Universal Character Set), once it became clear that more than 216 (65,536) code points were needed.
In computer and machine-based telecommunications terminology, a character is a unit of information that roughly corresponds to a grapheme, grapheme-like unit, or symbol, such as in an alphabet or syllabary in the written form of a natural language.
ISO/IEC 646 is the name of a set of ISO standards, described as Information technology — ISO 7-bit coded character set for information interchange and developed in cooperation with ASCII at least since 1964. Since its first edition in 1967 it has specified a 7-bit character code from which several national standards are derived.
ISO/IEC 8859-5:1999, Information technology — 8-bit single-byte coded graphic character sets — Part 5: Latin/Cyrillic alphabet, is part of the ISO/IEC 8859 series of ASCII-based standard character encodings, first edition published in 1988. It is informally referred to as Latin/Cyrillic. It was designed to cover languages using a Cyrillic alphabet such as Bulgarian, Belarusian, Russian, Serbian and Macedonian but was never widely used. It would also have been usable for Ukrainian in the Soviet Union from 1933 to 1990, but it is missing the Ukrainian letter ge, ґ, which is required in Ukrainian orthography before and since, and during that period outside Soviet Ukraine. As a result, IBM created Code page 1124.
ISO/IEC 8859-6:1999, Information technology — 8-bit single-byte coded graphic character sets — Part 6: Latin/Arabic alphabet, is part of the ISO/IEC 8859 series of ASCII-based standard character encodings, first edition published in 1987. It is informally referred to as Latin/Arabic. It was designed to cover Arabic. Only nominal letters are encoded, no preshaped forms of the letters, so shaping processing is required for display. It does not include the extra letters needed to write most Arabic-script languages other than Arabic itself.
PETSCII, also known as CBM ASCII, is the character set used in Commodore Business Machines (CBM)'s 8-bit home computers, starting with the PET from 1977 and including the C16, C64, C116, C128, CBM-II, Plus/4, and VIC-20.
A telegraph code is one of the character encodings used to transmit information by telegraphy. Morse code is the best-known such code. Telegraphy usually refers to the electrical telegraph, but telegraph systems using the optical telegraph were in use before that. A code consists of a number of code points, each corresponding to a letter of the alphabet, a numeral, or some other character. In codes intended for machines rather than humans, code points for control characters, such as carriage return, are required to control the operation of the mechanism. Each code point is made up of a number of elements arranged in a unique way for that character. There are usually two types of element, but more element types were employed in some codes not intended for machines. For instance, American Morse code had about five elements, rather than the two of International Morse Code.
ArmSCII or ARMSCII is a set of obsolete single-byte character encodings for the Armenian alphabet defined by Armenian national standard 166–9. ArmSCII is an acronym for Armenian Standard Code for Information Interchange, similar to ASCII for the American standard. It has been superseded by the Unicode standard.
Extended ASCII character encodings are eight-bit or larger encodings that include the standard seven-bit ASCII characters, plus additional characters. Using the term "extended ASCII" on its own is sometimes criticized, because it can be mistakenly interpreted to mean that the ASCII standard has been updated to include more than 128 characters or that the term unambiguously identifies a single encoding, neither of which is the case.
The ISO basic Latin alphabet is a Latin-script alphabet and consists of two sets of 26 letters, codified in various national and international standards and used widely in international communication. They are the same letters that comprise the English alphabet.
JIS X 0208 is a 2-byte character set specified as a Japanese Industrial Standard, containing 6879 graphic characters suitable for writing text, place names, personal names, and so forth in the Japanese language. The official title of the current standard is 7-bit and 8-bit double byte coded KANJI sets for information interchange. It was originally established as JIS C 6226 in 1978, and has been revised in 1983, 1990, and 1997. It is also called Code page 952 by IBM. The 1978 version is also called Code page 955 by IBM.
In mobile telephony GSM 03.38 or 3GPP 23.038 is a character encoding used in GSM networks for SMS, CB and USSD. The 3GPP TS 23.038 standard defines GSM 7-bit default alphabet which is mandatory for GSM handsets and network elements, but the character set is suitable only for English and a number of Western-European languages. Languages such as Chinese, Korean or Japanese must be transferred using the 16-bit UCS-2 character encoding. A limited number of languages, like Portuguese, Spanish, Turkish and a number of languages used in India written with a Brahmic scripts may use 7-bit encoding with national language shift table defined in 3GPP 23.038. For binary messages, 8-bit encoding is used.
A bit-paired keyboard is a keyboard where the layout of shifted keys corresponds to columns in the ASCII (1963) table, archetypally the Teletype Model 33 (1963) keyboard. This was later contrasted with a typewriter-paired keyboard, where the layout of shifted keys corresponds to electric typewriter layouts, notably the IBM Selectric (1961). The difference is most visible in the digits row : compared with mechanical typewriters, bit-paired keyboards remove the _ character from 6 and shift the remaining &* from 7890 to 6789, while typewriter-paired keyboards replace 3 characters: ⇧ Shift+2 from " to @⇧ Shift+6 from _ to ^ and ⇧ Shift+8 from ' to *. An important subtlety is that ASCII was based on mechanical typewriters, but electric typewriters became popular during the same period that ASCII was adopted, and made their own changes to layout. Thus differences between bit-paired and (electric) typewriter-paired keyboards are due to the differences of both of these from earlier mechanical typewriters.
This article incorporates public domain material from the General Services Administration document: "Federal Standard 1037C".(in support of MIL-STD-188)
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