KOI7 is a 7-bit character encoding, designed to cover Russian, which uses the Cyrillic alphabet.
In Russian, KOI7 stands for Kod Obmena Informatsiey, 7 bit (Код Обмена Информацией, 7 бит) which means "Code for Information Exchange, 7 bit".
Shift Out (SO) and Shift In (SI) control characters are used in KOI7, where SO starts printing Russian letters, and SI starts printing Latin letters again, or for lowercase and uppercase switching.
The dollar sign character ("$" hex 24), however, was often replaced with the universal currency sign "¤" in Soviet computers. A popular legend has it that this was to demonstrate independence of the American-dominated computer industry — which was ironic, since a significant number of Soviet computers were actually implementations of various American designs.