The Fast Universal Digital Computer M-2

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М-2 was developed in the Laboratory of Electrical Systems in the Institute of Energy of the USSR Academy of Science (the Laboratory of Controlling Machines and Systems at AS USSR since 1957, the Institute of Electronic Controlling Machines since 1958) under the direction of an AS acotiate I.S. Brouk. The M-2 development team consisted, at different development stages, of 7 to 10 engineers: M. A. Kartsev, T. M. Aleksandridi, V. V. Belynsky, A. B. Zalkind, V. D. Knyazev, V. P. Kuznetsova, Yu. A. Lavrenyuk, L. S. Legezo, G. I. Tanetov, A. I. Schurov. The leader of the team was M. A. Kartsev.

The computer was developed and assembled in the period since April till December, 1952. Since 1953, M-2 was used for solving applied tasks on round-the-clock basis. In the winter of 1955 and later in 1956, the computer was essentially upgraded, the capacity of its ferrite core-based main memory reached the amount of 4096 numbers. The ferromagnetic memory was developed for M-2 by the team directed by M. A. Kartsev (It also included O. V. Rosnitcky, L. V. Ivanov, E. N. Filinov, V. I. Zolotarevsky).

M-2 was a digital computer with stored program. Its architecture was partly based on the principles that were embodied in one of the first Soviet computers, M-1, put into operation in the spring of 1952. 3-addresses-for-operands instruction set was chosen for М-2: it was considered the most adequate to the nature of calculations (an instruction included the op code, the addresses of two operands and the result code). Instruction format was 34-bit. i.e.:

• Opcode – 4 bits;
• Codes of three addresses 10 bits each (considering the RAM capacity of 1024 numbers).

In order to reduce the code size, the combined 4- and 16-based notation was used for the computer. The first two binary bits of an address were coded as a 4-based digit and the rest eight binary bits were coded as two hexadecimal digits.

The instruction set of M-2 comprised 30 instructions (4-bit opcode could be complemented with additional properties that were specified in the addresses and were unused in some instructions).

The M-2 instruction set included:

• six arithmetic instructions;
• two types of comparing instructions (algebraic and absolute comparison);
• seven format-switching instructions (from floating to fixed point and vise versa, from single to double precision and vise versa, switching to fixed point and double precision simultaneously, etc.)
• one instruction for logical multiplying two numbers;
• carry and sign change instructions;
• four instructions of data input;
• three instructions of data output;
• four instructions to rewind the magnetic tape of the external storage device;
• the "stop" instruction.

The M-2 computer could process binary data both as fixed and floating point numbers. The precision was up to 8 decimal digits for floating point calculations and up to 10 decimal digits for fixed point calculations. Double precision calculations were also possible.

The internal storage devices included the main electrostatic device (standard cathode-ray tubes) that held up to 512 numbers and had regeneration cycle of 25 µs, and an additional magnetic drum that held up to 512 numbers and rotated at 2860 revolutions/min.

The external storage device – a magnetic tape drive – held up to 50 thousand numbers. Data was input from a punched tape reader and output to a teletypewriter.

M-2 had parallel arithmetic unit with four trigger registers.

The average computer performance was 2 thousand instructions per second.

The control and arithmetic logical circuits used valves and semiconductor diodes.

The total number of electronic tubes was 1879, including 203 in the power supplies. The power was supplied from three-phase alternating current circuit of 127/220 V, and the system consumed 29 kW.

The computer occupied the area of 22 sq. m. Its main units and blocks were placed in four boxes on a single foundation, which also carried the power supplying box. The computer also had a control console with control switches and lamps that indicated the state of triggers of the arithmetic, selector and starting registers. M-2 had an air-cooling system with closed cycle.

Each computer unit consisted of separate blocks that were based on the chassis attached to the box frames. The M-2’s electronic part was assembled of dismountable valve sub-blocks with 14- or 20-pin plugs. The implemented structural solutions simplified the replacement of faulty valves, and also made it easier to localize malfunctions with the help of monitoring stands.

The computer was put into operation 1953, and since that time its software was accumulated in a library of standard programs and subroutines (written by A. L. Broudno and M. M. Vladimirova who were assisted by A. S. Kronrod and G. M. Adelson-Velsky).

The M-2 computer was used by the Institute of Atomic Energy (under academician S. L Sobolev), the Institute of Theoretical and Experimental Physics at AS USSR (under academician A. I. Alikhanov), the Institute of Problems of Mechanics at AS USSR (calculations related to durability of dams at Kuibyshev and Volga hydroelectric power stations), the Termotechnical (heat engineering) Laboratory at AS USSR (under academician M. A. Mikheev), the Air-Force Academy, the Artillery Academy, the Institute of Stalproyekt, the bureau led by academician A. I. Berg and many other scientific and industrial organizations. In 1953, complicated computing tasks for the needs of national defense, science and economy could be solved with the help of computers of three types, i.e. with BESM, Strela and M-2.

An informal society of programmers who worked in different organizations was formed around M-2. Among them were G. M. Adelson-Velsky, V. L. Arlazarov, M. M. Bongard, A. L. Broudno, M. Ya. Vainshtein, D. M. Grobman, A. S. Kronrod, E. M. Landis, I. Ya. Landau, A. L. Lunts. Besides developing merely practical methods of programming in M-2 codes, they were engaged in the solving of game, pattern recognition and diagnostics tasks. The results of these researches helped to develop brand-new methods of exhaustive search, in particular, the branches and bounds algorithm and to build reference systems based on logarithmic notation and search.

The First International Match of Chess Programs was won by the program developed by A. S. Kronrod and V. L. Arlazarov for the M-2 computer.

The experience of programming of tasks in M-2 codes has resulted in programming in informative denotations (A.L. Broudno).

The main Features of M-2

1. M-2 had about the same performance as the Strela computer but occupied 6 times less area, consumed 8 times less electric power and cost 10 times less.
2. The use of semiconductor diodes in the logical circuits for calculations and control allowed to considerably reduce the number of valves. The diode-based logic implemented in M-1, M-2 and M-3 later became a prototype of diode-transistor logic (DTL) for computers of the second and third generations.
3. The idea of short instruction and address codes in the 34-bit 3-addresses-for-operands instruction format, combined with the switching instructions (that was proposed and realized by M. A. Kartsev in M-2), later was transformed into the principle of creating the executable addresses in the system architecture of the computers of the second and third generations.
4. The M-2 main memory was based on 34 standard cathode-ray tubes (such as 13 L037) rather than on specialized potentioscopes that were used in Strela and BESM computers. This was a complicated engineering problem that was solved by T. M. Aleksandridi and Yu. A. Lavrenyuk and thus the required parameters for memory were met and the difficulties of equipping computer with specialized potentioscopes (that the BESM development team ran into) were avoided.

The magnetic drum for the additional internal storage device was developed by A. I. Schurov and manufactured in the laboratory simultaneously with development of the computer.

An ordinary rolling teletypewriter served as the data output device for M-2. This solution made M-2 easier to operate remotely. In February 1957, the M-2 computer with a remote terminal (console) was demonstrated at VDNH exhibition (now VVC) in the Hall of AS USSR.

References:

1. M. A. Kartsev, T. M. Aleksandridi, V. D. Knyazev, and others. The M-2 Fast Computing Machine. Cordinated by I. S. Bruk, an associate of AS USSR, Gostechteoretizdat, 1957.
2. M. A. Kartsev. The Arithmetic Unit of the M-2 Computing Machine. The Materials of the "Paths of Development of the Soviet Mathematical Mechanical Engineering and Instrumental Industry" Congress. The Universal Digital Machines section. Part 1. Moscow, March 12-17, 1956.
3. T. M. Aleksandridi. The Electrostatic Storage Device of M-2. The Universal Digital Machines section. Part 1. Moscow, March 12-17, 1956.
4. The M-2 Fast Electronic Computing Machine. Electricity N9, 1956.