KOI7
KOI-7 (КОИ-7) is a 7-bit character encoding, designed to cover Russian, which uses the Cyrillic alphabet.
In Russian, KOI-7 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 KOI-7, where SO starts printing Russian letters (KOI-7 N1), and SI starts printing Latin letters again (KOI-7 N0), or for lowercase and uppercase switching. This version is also known as KOI7-switched aka csKOI7switched.
On ISO 2022 compatible computer terminals KOI7-switched can be activated by the escape sequence ESC ( @ ESC ) N LS0.
KOI-7 was used on machines like the SM EVM (СМ ЭВМ) and DVK (ДВК); KOI-7 N2 was utilized in the machine-language of the Электроника Д3-28 (Elektronika D3-28) as four-digit hexadecimal code, БЭСМ-6 (BESM-6), where it was called ВКД, internal data code). The encodings were also used on RSX-11, RT-11 and similar systems.
KOI-7 N0 (КОИ-7 Н0) is identical to the IRV set in ISO 646:1983. Compared to US-ASCII, the dollar sign ("$") at codepoint 24hex) was replaced by the universal currency sign "¤", but this wasn't maintained in all cases, in particular not after the fall of the Iron Curtain. Likewise, the IRV set in ISO/IEC 646:1991 also changed the character back to a dollar sign.
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