High Quality Content by WIKIPEDIA articles! BESM (БЭСМ) is the name of a series of Soviet mainframe computers built in 1950-1960s. The name is an acronym for "Bolshaya Elektronno-Schetnaya Mashina" ("Большая Электронно-Счётная Машина"), literally "Large Electronically Computing Machine". The series began as a successor to MESM ("Malaya Elektronno-Schetnaya Mashina", "Small Electronically Computing Machine"). MESM was built between 1948 and 1951 and was one of the first electronic computers produced in the continental Europe.