CP866 is a Cyrillic code page to be used with MS-DOS. It is based on the "alternative character set" of GOST 19768-87. The code page had wide usage during MS-DOS era because it conserve the pseudographic symbols layout (not in Windows-1251) and has alphabetically sorted (but not continuos) (not in KOI8-R) cyrillic letters. The Cyrillic alphabet (pronounced , also called azbuka, from the old name of the first two letters) is an alphabet used for several East and South Slavic languages—Belarusian, Bosnian, Bulgarian, Macedonian, Russian, Rusyn, Serbian, and Ukrainian—and many other languages of the former Soviet Union, Asia and Eastern Europe. ... Code page is the traditional IBM term used for a specific character encoding table: a mapping in which a sequence of bits, usually a single octet representing integer values 0 through 255, is associated with a specific character. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... Windows-1251 is an 8-bit character encoding, designed to cover languages that use the Cyrillic alphabet such as Russian and other languages. ... KOI8-R is an 8-bit character encoding, designed to cover Russian, which uses the Cyrillic alphabet. ...

Code page layout

Only the upper half (128–255) of the table is shown, the lower half (0–127) being plain ASCII. There are 95 printable ASCII characters, numbered 32 to 126. ...