DEMOS was a Unix-like

Unix-like

A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification....

 operating system

Operating system

An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...

 developed in the Soviet Union

Soviet Union

The Soviet Union , officially the Union of Soviet Socialist Republics , was a constitutionally socialist state that existed in Eurasia between 1922 and 1991....

. It was derived from BSD.

Its development was initiated in the Kurchatov Institute of Atomic Energy in Moscow

Moscow

Moscow is the capital, the most populous city, and the most populous federal subject of Russia. The city is a major political, economic, cultural, scientific, religious, financial, educational, and transportation centre of Russia and the continent...

 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

MNOS

MNOS was a Unix-like operating system developed in the Soviet Union. It was derived from Unix Version 6 and consequently heavily modified to incorporate many features of BSD Unix...

 (a clone of Unix Version 6

Version 6 Unix

Sixth Edition Unix, also called Version 6 Unix or just V6, was the first version of the Unix operating system to see wide release outside Bell Labs. It was released in May 1975 and, like its direct predecessor, targeted the DEC PDP-11 family of minicomputers...

). MNOS

MNOS

MNOS was a Unix-like operating system developed in the Soviet Union. It was derived from Unix Version 6 and consequently heavily modified to incorporate many features of BSD Unix...

 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 charsets (KOI-8 and U-code, used in DEMOS 1 and MNOS, respectively).

Initially it was developed for SM-4

SM-4

The SM-4 was a Polish PDP-11/40 computer clone, in the second half of 1980s. It was very popular in science and technology.The standard configuration included 128 or 256 KB core memory, tape puncher, two RK-05 removable 2.5 MB disks and two RK-05F fixed disks, two TU-10 drives and Videoton...

 (a PDP-11/40 clone). Later it was ported to Elektronika

Elektronika

Electronika is the brand name used for many different electronic products such as calculators, electronic watches, portable games and radios in the Soviet Union and, nowadays, in Russia...

-1082, BESM

BESM

BESM is the name of a series of Soviet mainframe computers built in 1950-1960s. The name is an acronym for "Bolshaya Elektronno-Schetnaya Mashina" , literally "Large Electronically Computing Machine". The series began as a successor to MESM...

, ES EVM

ES EVM

ES EVM was a series of clones of IBM's System/360 and System/370 mainframes, released in the Comecon countries under the initiative of the Soviet Union since the 1960s. Production continued until 1998...

, clones of VAX-11

VAX-11

The VAX-11 was a family of minicomputers developed and manufactured by Digital Equipment Corporation using processors implementing the VAX instruction set architecture . The VAX-11/780 was the first VAX computer.- VAX-11/780 :...

, and a number of other platforms, including PC/XT

PC/XT

PC/XT has multiple possible meanings:* "PC/XT" may simply be shorthand for the IBM Personal Computer XT.* "PC/XT" may also be intended to mean "the IBM Personal Computer and/or the IBM Personal Computer XT"....

, Elektronika

Elektronika

Electronika is the brand name used for many different electronic products such as calculators, electronic watches, portable games and radios in the Soviet Union and, nowadays, in Russia...

-85 (a clone of DEC Professional

DEC Professional (computer)

The Professional 325 and Professional 350 were PDP-11 compatible microcomputers introduced in 1982 by Digital Equipment Corporation as high-end competitors to the IBM PC...

), and a number of Motorola 68020

Motorola 68020

The Motorola 68020 is a 32-bit microprocessor from Motorola, released in 1984. It is the successor to the Motorola 68010 and is succeeded by the Motorola 68030...

-based microcomputers.

The development of DEMOS effectively ceased in 1991, when the second project of the DEMOS team, RELCOM

RELCOM

RELCOM or Relcom , an acronym for "RELiable COMmunications" is a computer network in Russia. It was launched in the Soviet Union on August 1, 1990 in the Kurchatov Institute in collaboration with DEMOS co-operative RELCOM or Relcom , an acronym for "RELiable COMmunications" is a computer network in...

, took priority.

The originally suggested name was УНАС (UNAS), which was a volapukish word play on Unix; "у них" ("u nih") in Russian means "at theirs", "у нас" ("u nas") means "at ours", but a more serious management dismissed this idea in favor of a traditional "alphabet soup".