BESM

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For other uses, see BESM (disambiguation).

BESM (БЭСМ) is the name of a series of Russian mainframe computers. It stands for "Большая Электронно-Счётная Машина" (Bolshaya Elektronno-Schetnaya Mashina) in Russian, which can be translated as "Large Electronic Computing Machine", or simply "Large Computer".

Several types of BESM have been built.

BESM-1 was built in 1953 using approximately 5,000 vacuum tubes. Only one such machine was ever built. At the time of completion, it was the fastest computer in Europe. The floating point numbers were represented as 39-bit words: 32 bits for the numeric part, 1 bit for sign, and 1 + 5 bits for the exponent. It was capable of representing numbers in the range 10−9 – 1010. BESM-1 had 1024 words of read/write memory using ferrite cores, and 1024 words of read-only memory based on semiconducting diodes. It also had external storage: 4 magnetic tape units of 30,000 words each, and fast magnetic drum storage with a capacity of 5120 words and an access rate of 800 words/second. The computer was capable of performing 8–10 KFlops. The energy consumption was approximately 30 kW, not accounting for the cooling systems.

BESM-2 also used vacuum tubes.

BESM-3M and BESM-4 were built using transistors. Their architecture was similar to that of the M-20 and M-220 series. The word size was 45 bits. 30 BESM-4 machines were built.

BESM-6 was a completely new supercomputer system. It was designed at the Institute of Precision Mechanics and Computer Engineering in 1965, with production starting in 1967. Like its predecessors, the BESM-6 was made up of discrete components; it did not use integrated circuits. The word size was 48 bits, with an address size of 15 bits. The system had addressable memory in a base configuration of 32K words (192K bytes) extendable up to 128K words, operating at a clock frequency of 10 MHz, with a nominal performance of 1 MFlops. The BESM-6 was widely used in USSR in 1970s for various number-crunching tasks. A total of 355 of these machines were built. Production ended in 1987.

BESM-6 was the first Soviet computer that was provided with an operating system and a Fortran compiler.

The later development of BESM-6 was Elbrus.

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