BESM (БЭСМ) is the series of Soviet mainframe computers built in 1950–60s. The name is an acronym for "Bolshaya[1] (or Bystrodeystvuyushchaya) [2] Elektronno-schotnaya Mashina" ("Большая электронно-счётная машина" or "Быстродействующая электронно-счётная машина"), meaning "Big Electronic Computing Machine" or "High-Speed Electronic Computing Machine". It was designed at the Institute of Precision Mechanics and Computer Engineering