DEMOS's development was initiated in the Kurchatov Institute of Atomic Energy in Moscow in 1982, and development continued in cooperation from other institutes, and commercialized by DEMOS Co-operative which employed most key contributors to DEMOS and to its earlier alternative, MNOS (a clone of Version 6 Unix). MNOS and DEMOS version 1.x were gradually merged from 1986 until 1990, leaving the joint OS, DEMOS version 2.x, with support for different Cyrillic script character encoding (charsets) (KOI-8 and U-code, used in DEMOS 1 and MNOS, respectively).