M-20 Computer

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1. М-20 - an Electronic Computing Machine for General Computations.
2. Chief designer was academician of the AS USSR S. A. Lebedev; chief developer assistants were M.K. Soulim (PhD in engineering) and M.R. Shura-Bura (PhD in physics and math); the development team: P.P. Golovistikov (PhD in engineering), V.Ya. Alekseyev (PhD in engineering), V.V. Bardizh (PhD in engineering), V.N. Laut (PhD in engineering), A.A. Sokolov, M.V. Tyapkin, A.S. Fyodorov.
3. Developing organization: the Institute of Precise Mechanics and Computation Equipment (ITM and VT) and the Special design bureau No. 245 (SKB-245).
4. Producer: Kazan Plant of Computing Machines.
5. Development stage was completed by 1958.
6. Manufacturing started in 1958.
7. Manufacturing stopped in 1964.
8. Number of computers produced - 20.
9. Applications: solving tasks in various fields of science and engineering.
10. M-20 was a single-processor computer. Several original architectural solutions were implemented in the processor: overlapping the executed commands (i.e. pipeline processing), accelerated addition and multiplying operations (due to improved operating of carry circuits - the "rough" carry chain was introduced in addition to fly-through carry) and multiplying a factor by two bits at a time. The computer used 45-bit binary floating point notation. Its main memory was based on ferromagnetic cores and held up to 4096 words. The peripheral memory consisted of magnetic drums and tapes.
11. Circuitry: dismountable blocks of two electronic tubes. The impulse principle (dynamic triggers) was applied in the circuits of parallel devices; thereby the total amount of computer valves was reduced to 1600 items. The logical circuits used semiconductor diodes that were exploited unexcessively due to the dynamic triggering method. This allowed to make the computer operation more reliable.
12. Architecture and technology: the computer occupied seven boxes. Each box contained six cards (circuit boards). 30-pin knife-edge plugs were used.
13. System software: the IS-2 library of standard subroutines.
14. Characteristics:
    • Average performance - 20 thousand instructions per second.
    • Occupied area - 170-200 sq. m.
    • Consumed power - 50 kW (not including the cooling system); the standard 220V/50Hz power circuit was used for M-20.
15. Main features: The M-20 computer was one of the fastest and most reliable of the first-generation computers all over the world. The general improvement of overall performance was achieved due to new architectural solutions and impulse principle of the circuit structure as well as to introducing:
    • index arithmetic that in many cases allowed to avoid command variables;
    • new logical operations of the processor;
    • instruction sets with automatic address changing;
    • overlapping arithmetic unit operation and fetching commands from the main memory;
    • overlapping data output and operation of the processor.
16. The M-20 computer and some of its components were patented. There were numerous publications on the subject.