**Triple computers “Setun” and “Setun 70”**
At the beginning of 1956 a department of electronics was organized in the computer center of MSU on the initiative of S.L. Sobolev, a member of the Academy, the head of the department of calculating mathematics at the mechanical and mathematical faculty of MSU and a seminar began to work with the aim of practical sample of digital machine creation to use it in universities and also in laboratories and design burros of industrial enterprises. It was necessary to work out a small computer, simple in mastering and using, reliable, not expensive but at the same time effective in the wide range of problems.

A detailed studying of present at that time computers and technical abilities of their realization was being done during a year. This led to a nonstandard decision to use in the created machine not the binary but the triple code realizing the very “balanced” system of calculating that was called “may be the most graceful one” [1] by Knut D. twenty years later and as it became well known the advantages of witch were revealed by Shennon K. in 1950. [2].

Unlike the common binary code that is used in modern computers with numbers 1, 0. This code is not of arithmetical full value as it is impossible to represent the negative numbers in it, but triple code with numbers -1, 0, 1 provides optimal arithmetic’s of numbers formation with a sign. So there is not only need in artificial and imperfect additional, direct back codes of numbers but the arithmetic’s gets a row of considerable advantages: uniformity of number code, variable length of operands, the singular operating shift, triple value of the function – “sign of a number”, the optimal rounding off numbers by simple cutting off lower classes, the compensation of errors rounding in the process of calculating [3].

The triple computer “Setun” [4, 5] is an experimental sample that was created, assembled and by the end of the year began to use by the collaborators of the electronics department. As the experience of its mastering, program facilities and variable practical appliances showed that the computer met with all requirements and all foreseen tasks for its creation.

This success showed the goodness of the triple digital equipment taking into account that the creation of such equipment was for the first time and completed by a small group of the beginners (8 graduate students MEI and MSU, 12 technicians and laboratory assistants) and the work was done in short period of time. By complication in comparison with the binary elements of memory and elementary operations they simplify and make the architecture of the triple equipment more natural.

With minimum set of commands (only 24 one address commands) “Setun” provided an opportunity of calculations with fixed and floating point, had an index register, the meaning of witch can be as added as subtracted when modifying an address, provided the operation of adding with product that optimized polymons calculation, the operation of class multiplying and three commands of conditional transition according to the sign of the result. Simple and effective architecture gave an opportunity to facilitate the computer with the programming system and a set of applying programs [6] by a small group of programmers by the end of 1959. That was enough for interdepartmental testing of the experimental sample in April, 1960.

According to the results of the testing computer “Setun” was acknowledged as “the first working sample of a universal computer on the base of elements without lamps”. That had the following characteristics: “high productivity, sufficient reliability, small forms simple technical service”. The Council of Ministers of USSR made a resolution of the serial production of “Setun” at the Kazan plant of mathematical computers by the recommendation of the Interdepartmental Committee of Experts. But for some reason the officials from radio electronically department didn’t like the triple computer: they didn’t provide the serial production of the computer sample and when it was provided with using constructive of the computer M-20 that was produced on the plant didn’t help the output progress. However the amount of orders from e.g. abroad grew they limited the output declining orders and in 1965 the production was stopped. Also they prevented the mastering of the machine in CSSR where a big production of it was planning. The reason for such a strange “politics” could the very low price of “Setun” – 27,5 thousand of rubles, because of the perfect production of its magnetic digital elements on Astrahanj plant EA and EP, 3 rubles and 50 kopeks for one element (a machine has about 2 thousand elements). It is essential that electromagnetic elements of “Setun” let accomplish the threshold realization of triple logic really economical, natural and reliable. An experimental sample was destructed in an absolute working state after 17 years exploitation in CC of MSU, only three elements with defects were changed during the first year and the machine didn’t need any repairing of inner devices. The serial machines functioned well in different climatic zones from Odessa and Ashkhabat to Yakutsk and Krasnoyarsk without any service and new parts.

Thanks to the simplicity and natural architecture and also rational constructed programming system including interpretive systems: IP-2 (shifting comma, 8 decimal signs), IP-3 (shifting comma, 6 decimal signs), IP-4 (complex numbers, 8 decimal signs), IP-5(shifting comma, 12 decimal signs), auto code POLIZ with operating system and library of standard programs (shifting comma, 6 decimal signs), computer “Setun” was well mastered by users in universities, industry enterprises and SRI (Scientific Researching Institute) and was an effective mean in solving practical important problems in very different fields from scientific researching modeling and design calculating to weather forecast and optimization of enterprising management [7]. At seminars of “Setun” computer users that were held in MSU (1965), Ludinovskij locomotive building plant (1968), Irkutsk Polytechnic Institute 91969) were presented dozens of reports about well economic applying of these computers. “Setun” thanks to the natural triple symmetric code appeared a real universal calculating device, positively proved itself to be technical studying mean of computer mathematics in more than 30 universities. For the first time an automotive system of computer studying was realized in military air engineering academy after Zhukovskij on the base of “Setun” [8].

Triple system of calculating was based on the same principle of number coding as binary system used in modern computers but the weigh of the category in it is not 2’ but 3’. And the categories themselves are not double (not bites) but triple (trits) - besides 0 and 1 there is the third value that is -1, thanks to it uniformly represented as positive as negative numbers. Value of n- triple number is defined by the same value of n-bite.

Where is a_{i}ε{1,0,-1} – value of a figure *i*‑category.

Figures in triple symmetrical system are better to mark in signs, i.e. instead of 1, 0, -1 put +, 0, -. For example decimal numbers 13, 7, 6, -6 in such a triple record will be 13 = +++, 7 = +-+, 6 = +-0, -6 = -+0. The sign change of a numbering the symmetrical code is equal to triple inversion, i.e. interchanging of all “+” into “-“and all “-“into “+”. The addition and multiplying in the triple symmetrical code are defined in the tables:

| + | 0 | – |

+ | + – | + | 0 |

0 | + | 0 | – |

– | 0 | – | – + |

| + | 0 | – |

+ | + | 0 | – |

0 | 0 | 0 | 0 |

– | – | 0 | + |

Unlike the binary one this arithmetic’s of numbers with a sign and the sign of the number is a figure of its higher category (not 0 one). Problems of numbers with a sign, that do not have in the binary code perfect solving, in the triple symmetrical code there is none and that is its advantage.

“Setun” computer can characterized as one address of logical doing with 9-triple code command , 18-triple register summarizer S and multiplier R, 5-triple index register of the address modification F and meter pointer of the fulfilling commands C and also one-bite pointer of a result sign *w*** **that regulate conventional transitions.

The operating memory – 162 9-triple cells – divided into 3 pages with 54 cells for one page changing with memory – magnetic drum with volume of 36 or 72 pages. Reading and recording into the operating memory can be by 18-triple and 9-triple words and a 9-triple word corresponds to the older half of 18-triple one in the registers S and R. The content of these registers is interpreted as number of fixed after the second from older categories point, i.e. according to module it is less than 4, 5. When calculating with floating point mantissa M of a normalized number satisfies the condition 0,5 <ú Mú <1,5 and the order in represented as a separate 5-triple word interpreted as whole number with a sign. Page two-stage structure of a memory with word address in the range of three pages OZU that has 5-triple addresses and 9-triple commands gave a unusual compact programs and at the same time high speed of the computer in spite of the fact that in interpreting systems magnet drum functions as an operating memory.

In 1967-69 A triple digital computer (“Setun 70”) was created on the base of the creation experience and practical applying of “Setun”. Its experimental sample appeared in April 1970. This computer is of nontraditional binary joint architecture that is oriented on the providing of good conditions for further development of its abilities by interpreting system method. [9]

They used arithmetic joint (joint of 18-triple operands) because of the polish inversion writing program POLIZ) usage as a computer language. It worked well on the computer “Setun”. POLIZ-program doesn’t consist of commands of this or that addresses but of short word logic – 6-triple triple bites. S an element of a program, a triple bite can be addressing or operating. Addressing triple bite is used as an operand or as an instruction to send addressing word from operating memory from one of three triple bites into operand joint. There are only 9 pages with 81 triples in each in the operating memory and for the access only three pages are opened at the moment, their numbers are in the “registers of printing”.

Operating triple bite points operations or procedures for operands joint and processor register. There are only 81 operations – 27 basic, 27 auxiliary and 27 that are programmed by a user.

The second system joint that has return addresses when processing of breaks and program fulfillment allowed realizing E. Dekster’s idea of structural programming on the “Setun 70” inputting call operation of a program, a call according to a condition and cycle program fulfillment. As a result procedure structural programming proved the advantages of Dekster’s method: the difficulty of program creating became 5-7 times less thanks to traditional testing ”arrangement” on examples. And programs got reliability, logic, understanding and modification. Then the peculiarities of “Setun 70” were the base for dialogue structural programming DSSP that was fulfilled on the computers of DVK type and personal computers. [10, 11]

But unfortunately the further development of “Setun 70” abilities by development its programming equipment was administratively stopped. They had to orient on the study computerization. “Setun 70” became the base for development and fulfillment of automotive computer system of teaching “Tutor” [12, 13] that had the principles of Y. A. Kamenskij’s “Great Didactics” The purpose of the computer in this system is not the “electron turning over pages” and multimedia effects but the checking of students understanding of what he\she is studying, overcoming misunderstandings and providing with real subject skills by exercises. Also computer notes the lesson itself giving an opportunity to the creator of the material to evaluate the effectiveness of using didactics methods and improve them.

Studying materials in “Tutor” are given in typed form with numbered sections, passages, exercises and note to the wrong answers, thanks to it computer interacts with a student easily giving the book the ability of communication with a reader with the help of simple terminal with digital keyboard and calculating indicator. The creation of studying materials for “Tutor” isn’t connected with computer programming and as practice showed teachers could create materials on Math’s, Physics, English and other subjects. Didactic effectiveness of the system was very high. So the course “Basic Fortran” students of MSU studied in “Tutor” for 10- 15 hours, students from economical department for 15 – 20 hours and showed better skills of programming in Fortran than after a usual semester course.

The fulfilled principle “book-computer” in “Tutor” gave an optimal computer usage as a studying mean practically in all respects: necessary equipment (microcomputer and connected with it 30-40 terminals like simple calculator), low price, reliable and easy mastering as by students as by teachers, the work in a regime of a dialogue is not difficult, fascinating and guarantees quick and good mastering of a subject if having good material organization. The applying system in MSU, MAI, VIA after Kujbishev, in school and for professional studying at a plant proved its effectiveness in wide range of subjects and studying levels. And “Tutor” has been used for 30 years for automatic tests and tests to identify the English language level of first year students to form groups according to levels.

But the great necessity of studying process improvement in our “informative” century “Tutor” wasn’t in need may be because of the low price and its simplicity and lack of display, mouse and hypertext. The fact is that information technologies of studying process is evaluated according to the number of computers and their power but not to their level and quality

**References **

- D. Knut . Programming skills for computer Algorithms v.2 – M.:MIR, 1997, p. 218

- C.E. Shannon Symmetrical notation for numbers.// the American mathematical monthly, v. 57, n.2, Feb. 1950, pp.90-93

- N.P. Brusenzov Notes about triple digital equipment//Architecture and programming of digital systems. – M.: MSU, 1984. pp.114-123

- N.P. Brusenzov Computer “Setun” of MSU// New developments in the field of calculating mathematics and equipment. Kiev, 1960. pp.226-234

- A small computer “Setun”/ N.P. Brusenzov, S.P.Maslov, V.P. Rozin, A.M.Tishulina –M., MSU, 1965.p.145.

- E.A.Zhogolev Command system and interpreting system for “Setun”//Calculating mathematics and mathematical physics, magazine, 1961, #3, pp.499-512

- Annotated guideof programs for “Setun”/ N.P.Brusenzov, V.A.Morozov,- M.:MSU, 1968, #2, 1971

- S.I.Kuznezov Materials on mathematical service of “Setun”, - M.,1964

- N.P. Brusenzov,E.A. Zhogolev Structure and algorithms of small computer functioning ///Calculating equipment and cybernetics questions, #8. L.1971, pp.34-51

- Dialogue system of structural programming/ N.P.Brusenzov, G.V.Zlatkus, I.A.Rudnev //programming equipment of microcomputers, - M., 1982, pp. 11-40

- Developing adapting language of a dialogue system of programming/ N.P.Brusenzov, Zakharov, I.A.Rudnev, C.A. Sidorov, N.A.Chanishev –M., 1987, p. 80

- Automative system of studying “Tutor”/ N.P. Brusenzov, S.P.Maslov, H. Ramil Alvares// calculating equipment and cybernetics questions, #13, -M., 1977, pp. 3-17

Microcomputer system of studying “Tutor”/ N.P.Brusenzov, S.P.Maslov, H. Ramil Alvares- M., 1990, p. 223