KOI (''КОИ'') is a family of several
code page
In computing, a code page is a character encoding and as such it is a specific association of a set of printable characters and control characters with unique numbers. Typically each number represents the binary value in a single byte. (In some co ...
s for the
Cyrillic script.
The name stands for ''Kod obmena informatsiey'' (russian: Код обмена информацией) which means "Code for Information Interchange".
A particular feature of the KOI code pages is that the text remains human-readable when the leftmost
bit is stripped, should it inadvertently pass through equipment or software that can only deal with 7 bit wide characters. This is due to characters being placed in a special order (128 codepoints apart from the Latin letter they sound most similar to), which, however, does not correspond to the alphabetic order in any language that is written in Cyrillic and necessitates the use of
lookup table
In computer science, a lookup table (LUT) is an array that replaces runtime computation with a simpler array indexing operation. The process is termed as "direct addressing" and LUTs differ from hash tables in a way that, to retrieve a value v wi ...
s to perform
sorting
Sorting refers to ordering data in an increasing or decreasing manner according to some linear relationship among the data items.
# ordering: arranging items in a sequence ordered by some criterion;
# categorizing: grouping items with similar pro ...
.
These encodings are derived from
ASCII on the base of some correspondence between Latin and Cyrillic (nearly phonetical), which was already used in
Russian dialect of Morse code and in
MTK-2
The Baudot code 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. ...
telegraph code. The first 26 characters from А (0xE1) in KOI8-R are А, Б, Ц, Д, Е, Ф, Г, Х, И, Й, К, Л, М, Н, О, П, Я, Р, С, Т, У, Ж, В, Ь, Ы, З.
KOI-7
The original KOI encoding (1967) was a 7-bit code page named
KOI-7 (''КОИ-7''), which did not contain lowercase letters.
In KOI-7, the codes of the 31 or 32 Russian letters are ordered according to the Latin letters. Other code points are the same as in
ASCII (however, the
dollar sign $ (code point 24
hex) may be replaced by the
universal currency sign ¤).
KOI-8
KOI-8 (КОИ-8), standardized in 1974 by GOST 19768, is an 8-bit
extensions of ASCII.
Originally it only included 32 lowercase and 31 uppercase Russian letters.
Later derivatives of KOI-8 constitute the family of encodings variously known as KOI8, KOI 8 and KOI-8.
The family members are:
*
KOI8-B (with
Ёё and
Ъ)
*
KOI8-R /
KOI8-RUSSIA for
Russian and
Bulgarian
Bulgarian may refer to:
* Something of, from, or related to the country of Bulgaria
* Bulgarians, a South Slavic ethnic group
* Bulgarian language, a Slavic language
* Bulgarian alphabet
* A citizen of Bulgaria, see Demographics of Bulgaria
* Bul ...
(RFC 1489).
*
KOI8-U /
KOI8-UKRAINE
KOI8-U (RFC 2319) is an 8-bit character encoding, designed to cover Ukrainian, which uses a Cyrillic alphabet. It is based on KOI8-R, which covers Russian and Bulgarian, but replaces eight box drawing characters with four Ukrainian letters Ґ, ...
for
Ukrainian
Ukrainian may refer to:
* Something of, from, or related to Ukraine
* Something relating to Ukrainians, an East Slavic people from Eastern Europe
* Something relating to demographics of Ukraine in terms of demography and population of Ukraine
* So ...
(RFC 2319).
*
KOI8-RU for
Ukrainian
Ukrainian may refer to:
* Something of, from, or related to Ukraine
* Something relating to Ukrainians, an East Slavic people from Eastern Europe
* Something relating to demographics of Ukraine in terms of demography and population of Ukraine
* So ...
,
Belorussian and
Russian.
*
KOI8-T
KOI8-T is an 8-bit single-byte extended ASCII character encoding adapting KOI8 to cover the Tajik Cyrillic alphabet. It was introduced by Michael Davis as an interim solution for representing Tajiki Cyrillic text in an interchangeable manner appr ...
for
Tajik
Tajik, Tadjik, Tadzhik or Tajikistani may refer to:
* Someone or something related to Tajikistan
* Tajiks, an ethnic group in Tajikistan, Afghanistan and Uzbekistan
* Tajik language, the official language of Tajikistan
* Tajik (surname)
* Tajik cu ...
.
*
KOI8-C, also
KOI8-CA, a proposal for
Caucasus and
Central Asia; hardly ever been used.
*
ISO-IR-111
ISO-IR-111 or KOI8-E is an 8-bit character set. It is a multinational extension of KOI-8 for Belarusian, Macedonian, Serbian, and Ukrainian (except Ґґ which is added to KOI8-F). The name "ISO-IR-111" refers to its registration number in the ...
/
KOI8-E (ECMA-113 (1st ed., 1986), multilingual for Slavic languages).
*
KOI8-F, KOI-8 Unified. Includes the letter allocations from both KOI8-U and KOI8-E, with a subset of the pseudographics from KOI8-R.
*
KOI8-K1 "Cyrillic-1" (defined in CSN 36 9103, ST SEV 358-88)
*
KOI8-O (formerly KOI8-C) for
Old Russian orthography.
Additionally,
GOST R 34.303-92 defines "KOI-8 V1" which is
ISO-IR-153 ISO-IR-153 (ST SEV 358-88) is an 8-bit character set that covers the Russian and Bulgarian alphabets. Unlike the KOI encodings, this encoding lists the Cyrillic letters in their correct traditional order. This has become the basis for ISO/IEC 8859 ...
, and "KOI-8 N1" and "KOI-8 N2" which are variants of
Code page 866.
[ ГОСТ Р 34.303-92]
Наборы 8-битных кодированных символов. 8-битный код обмена и обработки информации.
= 8-bit coded character sets. 8-bit code for information interchange. These do not follow the KOI-8 layout.
DKOI
DKOI is an
EBCDIC-based encoding used in
ES EVM mainframes. It has been defined by several standards: GOST 19768-74 / ST SEV 358-76, ST SEV 358-88 / GOST 19768-93, CSN 36 9103.
There are two variants:
*DKOI K1 (ДКОИ К1), each Cyrillic letter is given its own code point.
*DKOI K2 (ДКОИ К2), some Cyrillic letters (А, В, Е, К, М, Н, О, Р, С, Т, Х, а, е, о, р, с, у, х) are merged with visually identical Latin letters.
Latin variants
Some encodings are called KOI, but define Latin alphabets:
*
KOI8-CS /
KOI8-CS2 for
Czech and
Slovak (ČSN (Czech technical standard) 369103, devised by the
Comecon. This encoded Latin with
diacritics, as used in Czech and Slovak, rather than Cyrillic, but the basic idea was the same - text should remain legible with the 8-th bit cleared, thus e.g. Č became C etc.).
*KOI8-L2 "Latin-2" (defined in CSN 36 9103), ISO IR 139
ISO-IR-139
/ref> (almost identical to ISO 8859-2 (1987), but has the dollar sign and currency sign swapped)
*DKOI CS2 (defined in CSN 36 9103)
References
Further reading
*
*
External links
*
*
*
{{Character encoding
Character sets