Its development began in the IPK Minavtoproma in Moscow in 1981, and continued in cooperation with other institutes, including Kurchatov Institute. MNOS and its alternative, DEMOS version 1.x, were gradually merged from 1986 until 1990 resulting in the joint OS, DEMOS version 2.x. MNOS became the first fully bilingual version of Unix, and used a proprietary 8-bit Cyrillic script character set, U-code, which was later dropped in favor of KOI-8 in the process of merging with DEMOS.