BESM-6 Computer

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1. BESM-6 – an Electronic Computing Machine for general computations.
2. Chief designer: Hero of the Socialist Labour, academician S. A. Lebedev; the assistants of the chief designer: V. A. Mel'nikov, L. N. Korolev, V. S. Petrov, L. A. Teplitsky, the development team: A. A. Sokolov, V. N. Laut, M. V. Tyapkin, V. L. Li, L. A. Zak, V. I. Smirnov, A. S. Fedorov, O. K. Stcherbakov, A. V. Avayev, V. Ya. Alekseyev, O. A. Bol'shakov, V. F. Zhirov, V. A. Zhukovsky, Yu. I. Mitropol'sky, Yu. N. Znamensky, V. S. Chekhlov, and others; the software development team: V. P. Ivannikov, A. N. Tomilin, D. B. Podshivalov, M. G. Chaykovsky, V. F. Tyurin, E. Z. Lyubimsky, V. S. Shtarkman, N. N. Govorun, V. P. Shirikov, I. N. Silin, V. M. Kurochkin, Yu. M. Bayakovsky and others.
3. Developing organizations: the Institute of Precise Mechanics and Computation Equipment (ITM and VT) at the AS of the USSR and the Moscow Plant of Calculating and Analyzing Machines (SAM).
4. Producer: the Moscow Plant of Calculating and Analyzing Machines (SAM).
5. Development stage was completed by 1967.
6. Production started in 1968.
7. Production stopped in 1987.
8. Number of manufactured computers – 355.
9. Applications: the universal computer for solving a wide range of scientific and engineering tasks.
10. Description: For the first time in the history of the Soviet computer engineering, the principle of overlapping execution of commands was widely implemented (up to 14 single-address commands could be simultaneously executed on different stages), independently of the foreign computers (such as STRETCH by IBM). The chief designer of BESM-6 academician S. A. Lebedev named this technique the Principle of Water Pipe. Later it was widely used to increase the performance of universal computers. In modern terms this idea is called pipeline processing.

    The main memory, control unit and arithmetic logical unit operated on parallel and asynchronous basis due to buffer devices for intermediate storage of commands and data.

    A separate register memory for index storage and a separate address calculation unit (for fast modification of addresses with the help of index registers, including stack mode access) were specially designed to accelerate pipeline command processing.

    Associative memory on fast registers (used as cache) automatically saved the most frequently used operands, thereby reducing the number of calls to the main memory. "Stratification" of the main memory enabled various computer devices to access different memory units simultaneously. The systems of interrupts, memory protection, conversion of virtual addresses into the physical ones, and the privileged operation mode for OS made it possible to use the BESM-6 in multitasking and timesharing modes.

    Several accelerated multiplying and division algorithms (multiplying the factor by four digits, calculating four digits of a quotient in one clock pulse) were used in the arithmetic logic unit, as well as the adder that had no chains of fly-by carry and represented instruction result as two-row code (bit-by-bit sums and carry) processed the three-row input code (new operand and the two-row result of the previous command).

    The BESM-6 computers main memory was based on ferromagnetic cores and initially held 32 KB of 50-bit words. It was increased up to 128 KB in the further upgrades.

    Data exchange with external memory on magnetic drums (afterwards – on magnetic disks as well) and on magnetic tapes was performed in a parallel via seven high-speed buses (a prototype of a selector bus). Driver programs of the operating system managed the rest of peripheral units (item-by-item input/output) when the appropriate device generated interrupts.

11. System electronics: transistor current switches and diode-resistor combinatorial logic.
12. Construction: compact racks with short links between blocks mounted into a rack that had two-sided layout of slots.
13. Software: operating system (several operating systems were created, sych as D68, ND-70, OS IPM, Dispak, Dubna OS, Feliks OS), compilers for autocoder and for common high level languages, as well as for a number of specialized and experimental programming languages. The multi-language monitoring system Dubna was widely used. Various interactive service programs were developed. They were used to run applications interactively or in batch sessions.
14. Features:
    • Average performance – up to 1 million single-address instructions per second
    • Word length – 48 bits plus two control bits
    • Floating point notation
    • Clock speed – 10 MHz
    • Footprint – 150-200 sq. m.
    • Consumed power – 30kW (without cooling) from the 220 V / 50Hz power circuit
15. Main advantages: The BESM-6 computer embodied many brand-new technologies that determined the further development of general-purpose computers and ensured the BESM-6 operation durability and prolonged the period of its issue.

    BESM-6 had the brand-new circuitry with para-phase synchronization. The high clock speed of circuitry challenged the developer team to find new constructive solutions in order to decrease the size of wasted spaces and length of connections between units. This circuitry in combination with new constructive know-how enabled to increase the computer performance up to 1 million instructions per second in 48-bit floating-point operation mode. It was an unprecedented result considering relatively small amount of semiconductors and their performance (about 60 thousand transistors and 180 thousand diodes with the clock speed of 10 MHz).

    The system architecture of the BESM-6 computer featured an optimal set of arithmetic and logical operations, fast modification of addresses due to index registers (also capable to perform access in stack mode), and the technique of opcode extensions (extracodes).

    The developers of BESM-6 incorporated into its architecture the fundamental CAD principles. The machine’s operational and maintenance documentation was based on compact notation of the circuitry in ferms of the Boolean algebra. The manufacturers received the assembly documentation as a set of charts that have been produced by a service computer.

16. In 1969, S. A. Lebedev, V. A. Mel'nikov, L. N. Korolyov, A. A. Sokolov, V. N. Laut, M. V. Tyapkin, L. A. Zak, V. I . Smirnov, A. N. Tomilin, V. I. Semeshkin and V. A. Ivanov were awarded with the State Premium of the USSR for the development and organization of serial production of the BESM-6 computer. The computer and its components were patented. There are a Numerous publications on the subject followed.

    Several BESM-6 computers were installed abroad.