Russian Virtual Computer Museum. → M-3 Computer

# M-3 Computer

Translated by Alexander Nitusov

М-3 belonged to “small type” computers. It was designed by the team of young engineers under scientific guidance of academician I.S. Bruk at the Laboratory of electrical systems[1] of the Power Institute of the USSR Academy of Sciences (PI AS USSR).

In 1957-1958 the first computers M-3 were produced at the Scientific Research Institute of Electrotechnical Industry (SRIEI)[2] by its designers from I.S. Bruk's laboratory, upon their technical documentation. The director of SRIEI academician A.G. Iosifyan offered the project essential practical assistance.

Nikolay Matyukhin (then 26), a recent graduate from the Moscow Power Engineering Institute, headed the designing team.

Scientific designers of M-3 were: V.V. Belynskiy, V.M. Dolkart, N.A. Dorokhova, A.B. Zalkind, B.M. Kagan, G.N. Lopato, B.B. Melik-Shakhnazarov, V.N. Ovcharenko, Y.B. Przhiemskiy, G.I. Tanetov. Engineering designers: A.N. Patrikeev, A.P. Tolmasov.

The very first computer M-3 remained at the A.G. Iosifyan's SRIEI, one more was given to the design bureau of academician S.P. Korolev (space researches) and the third one sent to the Erevan Institute of Mathematics[3] (AS Armenian SSR) to its director academician Sergey Mergelyan[4] (then 30).

In Erevan M-3 became the prototype for computers ARAGATS and RAZDAN.

It was the basic machine for large computer family MINSK, produced in big series in Minsk, Byelorussia – designers G.P. Lopato, V.V. Przhiyalkovskiy.

One more M-3 was assembled at the Moscow institute of academician V.A. Trapesnikov (systems of automatics).

Technical documentation for M-3 was given to Hungarian Academy of Sciences; it was assembled in Budapest. That was the first Hungarian electronic computer.

It was also assembled at the telephone plant in Peking (under supervising of G.P. Lopato) and, correspondingly, became the first Chinese computer.

M-3 formed technical basic for the following development of the scientific school of control computers, at the (Moscow) All-Union Scientific Research Institute of Electronic Computers, founded by B.M. Kagan, V.M. Dolkart and many other young members of I.S. Bruk's “M-3 team”.

Differently to bigger machines, such as “Strela” and BESM, which needed considerable investments for their maintenance and special conditions for their stable operation (large premises, large power supply installations, cooling systems, etc.) M-3 was realization of I.S. Bruk's idea of “small computing machine”.

This computer was specially designed for solving mathematical problems at computer laboratories, scientific research institutes, design bureaus, etc. It integrated common differential equations and equations with partial derivatives (both linear and non-linear ones), it solved systems of linear equations with multiple unknowns, algebraic and transcendental equations, etc.

M-3 system of number representation – binary with fixed point: 30 binary places (in absolute value < 1) and a digit for number's sign.

N.Y. Matyukhin replaced “accustomed” three-address machine instruction code with two-address code with format:

- 6 opcode bits;
- two addresses with 12 opcode bits (addresses were presented with 4 octal digits).

Instruction codes were presented with two octal digits in the way that demonstrated the basic attribute – the kind of arithmetic operation, and additional attributes indicating the variant of operation performing.

Two of those variants were reserved for operations with modules of numbers. Other variants used possibilities of performed operation result storing in the arithmetic unit of the computer. Then it was used as an operand for the next operation. That was actually realization of the one-address operation mode, what reduced amount of memory accesses.

Instructions of conditional and unconditional punch-tape input operations transfer and transfer of numbers from one memory cell into another one were considered as logical and auxiliary operations. The sign of the result of former operation served as indicator of conditional transfer. Depending on it (“plus” or “minus”) a command was transferred via either the first or the second conditional transfer instruction address

The instruction system of M-3 provided programming flexibility, what significantly reduced number of accesses to magnetic memory drum.

M-3 arithmetic unit and the memory device were of parallel type (internal storage – magnetic drum with 2048 numbers capacity and with parallel data retrieval). Average performance of M-3 was 30 ops. After replacing magnetic drum with ferrite memory of the same capacity (it was designed and produced by the design bureau of Minsk computer plant) performance of M-3 rose up to 1500 – 2000 ops. During testing operations, in contact with diode memory device, arithmetic and control units demonstrated performance of 3000 ops. Doubling of the memory device (additional cabinet) increased the memory up to 4096 numbers.

Semiconductor components were widely used in M-3. Mismatched decoder was the main logical element of the computer. It was used in most of its arithmetical and control circuits.

Control device registers (of program decoder) of arithmetic unit were: information reception triggers (flip-flops) and valves made on electron tubes.

M-3 had altogether 774 electron valves, including 43 in power supply sources/devices. Power supply was provided from three-phase network of alternating current. Admissible voltage fluctuations: from minus 5% up to plus 10% . M-3 power consumption – 10 kWt.

The structure of M-3 consisted of three independent cabinets: the main one contained arithmetic unit, local and central control systems and computer control panel, the next case/cabinet contained storage devices with magnetic drum, amplifiers of recording and reading and numbers retrieval device. The third case contained power supply devices.

There was also the table with a teletype used as perforated tape input-output device. That also provided possibility for computer operation remote control via telephone and/or telegraph communication lines.

Electronic circuits of M-3 were made as removable two tubes sub-blocks provided with 20 or 14 contacts plug-in connectors.

All cabinets had open cycle air forced cooling. Needed premises did not exceed 3 м^{2}.

Autonomous power supply system could be also installed in a separate room. It consisted of three phase asynchronous motor and alternating and direct current generators.

## Main Features of М-3

Small digital computer М-3

1 – main cabinet with arithmetic unit (ALU), 2 – memory units cabinet, 3 – power sources.

Computer М-3 was built according to I.S. Bruk's concept of “small-size computer”. It made possible to widely use M-3 at research organizations and design bureaus without arranging special conditions or rooms. For comparison: the next in size computer URAL needed 60 sqm against 3.2 sqm of M-3.

*Asynchronous* principle of control device operation was implemented in M-3. Differently to *synchronous *principle of control, the sequence of М-3 single units and blocks operation was defined with their intercommunication mode – “order – response”. Transfer to the next primitive action was only allowed after receiving signal of the previous operation completion. Such design provided essential operational independence of different computer units. That also notably simplified its testing, adjustments and operation. Thus, in case of a failure in some block or device the computer automatically stopped, what simplified locating of the defective device or failed unit.

**Detailed biographies** of the persons mentioned here can be found at:

__http://www.computer-museum.ru/english/galglory_en/0.htm__

## **Used publications:**

- Belynskiy V.V., Dolkart V.M., Kagan B.M., Lopato G.P., Matyukhin N.Y. “Small Electronic Computer M-3”. In series “Advanced scientific, engineering and industrial experience”. Subject 40, № П-57-89. –М.:, affiliate of “ВИНИТИ”, 1957.
- Kagan B.M., Matyukhin N.Y., Belynskiy V.V., Dolkart V.M., Lopato G.P. Universal High-speed Computing Machine M-3”. In proceedings of the conference “The ways of development of the Soviet mathematical machine and instrumentation engineering”. Section of universal digital computers. Part 1. –М.: 12-17 March 1956.

## References:

1. From 1957 it was named – Laboratory of Control Machines and Systems AS USSR, and in 1958 developed into the Institute of Electronic Control Machines.

2. Later re-named into the All-Union Scientific Research Institute of Electromechanics – (AUSRIE).

3. Later transformed into the world famous Erevan Scientific Research Institute of Mathematical Machines

4. Mathematician S.N. Mergelyan became the youngest Soviet academician – at the age of 25.