The high-speed electronic computer of the U.S.S.R. Academy of Sciences (BESM)

BESM is the name given to the largest digital electronic computer of the U.S.S.R. The machine, which is of parallel-action type, can operate with numbers ranging from 2¿31 to 2+31. The calculations are carried out up to the 9th decimal digit, this being the accuracy required in solving the great majority of scientific problems. Both arithmetic and logical operations are carried out by a single universal parallel-action arithmetic unit, which consists of two receiving registers and an adder. Special cathode-ray tubes are employed for the operative memory. Besides these, the computer is provided with magnetic-drum and magnetic-tape storage. The numbers and instructions are put into the machine from a punched tape. The results of the calculations are recorded on magnetic tape, and a photoprmter, an independent device, is utilized to print them afterwards on a film. The BESM contains about 4500 valves, the average life of which is about 10000 hours. The machine operates 24 hours per day, 20% of the time being spent on checking in order to guarantee the reliability of the computer. The useful operating time of the machine is 72%, and the error losses total 8%. When solving complex problems on the machine the average operation speed is from 7000 to 8000 three-address operations per second.