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Russian Virtual Computer Museum.  → General Purpose Electronic Digital Computer BESM-1

General Purpose Electronic Digital Computer BESM-1

BESM-1 was the quickest computer in Europe and one of the quickest in the world at that time.

  1. Chief designer: academician S.A. Lebedev, member of the USSR Academy of Sciences; main designers: K.S. Neslukhovsky, P.P. Golovistikov, V.A. Melnikov, V.S. Burtsev, V.N. Laut, A.G. Laut, A.G. Zimarev, A.A. Sokolov, M.V. Tyapkin, V.A. Alexeev, V.P. Smiryagin, I.D. Visun, A.S. Fedorov, O.K. Shcherbakov, etc.
  2. Development organisation: Institute of Precession Mechanics and Computer Engineering (IPMCT AS USSR).
  3. Producing plant: Moscow plant of computation-analytical machines (CAM).
  4. Design completion year: 1953.
  5. Production beginning year: 1953.
  6. Total of produced computers: 1.
  7. Application field: solution of large-scale scientific and manufacturing problems.

Computer Description

BESM-1 structure

Three address instruction system. Number of places for instructions codes – 39.

Opcodes – 6 places; address codes – 3 addresses with 11 places for each.

Operation system of the computer consists of: arithmetic operations, codes transfer operation, logical operations and control operations. Operations could be performed with both normalized and unnormalized numbers.

Random Access Memory – RAM (operating memory) device of BESM-1 had capacity of 1024 numbers; it was made of ferrite cores (before that, memory devices based on mercury tubes and special tubes -potentialoscopes- had been tested for the purpose);

semiconductor diodes were mainly implemented in the Read Only Memory – ROM units with capacity – 1024 numbers.

ROM permanently contained some most often used constants and subroutines. Its contents remained unchanged during the computer operation.

Beside that there was external, magnetic tape, memory devices -four units with 30 thousand numbers stored in each, and also intermediate storage on magnetic drum, with 5120 numbers and access speed 800 num/sec.

Information input was performed with photoelectric reader from perforated tape (punch-tape). Output information was printed out on electromechanical printer.

BESM-1 Components

Basic components – cells, with two and four electron tubes; the cells contained various circuitry (flip-flops, valves, amplifiers, etc.). Computer BESM-1 had about 5000 electron valves.


BESM-1 was mounted on a single frame. Beside it there was a frame for external storage and a separate power supply system cabinet.

There was also a control board for turning computer on and off and for its operation control.

Computer Software

System software was not available for BESM-1.

Technical and Operational Characteristics

BESM-1 Specific Features

БЭСМ-1 was a parallel computer, it possessed a developed structure and advanced organisation of internal connections between its units and devices. Characteristics of the system units were well balanced. Basic principles of its design and internal organisation were later implemented in the following Soviet computers.

BESM-1 was able to perform operations over the numbers with floating point, what was its important advantage. It could process wide range of numbers: from 10-9 to 1010).

BESM-1 performed computations with high precession (to about 10 decimal places); although operations were performed with lower speed they were done with double precision.

A complex of controlling tests had been developed for the computer, what made possible quick malfunctions and failures locating in it. Also, a system of routine checking was developed for early detection of possible faults or defects.

BESM-1 received a (USSR) patent and some more patents were granted for some of its units. Numerous articles, manuals and other materials on BESM-1 have been published.

Published in museum, 16.12.2016

Started by Eduard Proydakov in 1997
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