History of computer hardware in Soviet Bloc countries
The history of computing hardware in the former Soviet Bloc is somewhat different from that of the Western world. As a result of the CoCom embargo, computers could not be imported on a large scale from capitalist countries. All computer hardware produced in Socialist countries were designed locally. This redevelopment led to some incompatibilities with International Electrotechnical Commission (IEC) and IEEE standards, such as spacing integrated circuit pins at 1⁄10 of a 25 mm length (colloquially a "metric inch") instead of a standard inch of 25.4 mm. This made Soviet chips unsellable on the world market outside the Comecon, and made test machinery more expensive.
BESM (БЭСМ) is the name of a series of Soviet mainframe computers built in the 1950s and 1960s. The name is an acronym for "Bolshaya Elektronno-Schyotnaya Mashina" ("Большая Электронно-Счётная Машина"), literally "Large Electronic Computing Machine". The series began as a successor to MESM, the first stored-program computer in the Soviet Union. While one MESM was built, some 250 BESM-6 machines were delivered. They were less advanced, for their timeframe, than the MESM was in its time.
ES EVM (ЕС ЭВМ, Единая система электронных вычислительных машин, meaning "Unified System of Electronic Computers") 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 starting in the 1960s. Production continued until 1998. The total number of ES EVM mainframes produced was more than 15,000.
In the period from 1986 to 1997, a series of PC-compatible desktop computers, called ПЭВМ ЕС ЭВМ (Personal Computers of ES EVM series), was also produced; the newer versions of these computers are still produced under a different name on a very limited scale in Minsk.
...
Wikipedia