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Electronic Computers, Transactions of the I.R.E. Professional Group on

Popular Articles (November 2014)

Includes the top 50 most frequently downloaded documents for this publication according to the most recent monthly usage statistics.
  • 1. Application of Boolean algebra to switching circuit design and to error detection

    Page(s): 6 - 12
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    A solution is sought to the general problem of simplifying switching circuits that have more than one output. The mathematical treatment of the problem applies only to circuits that may be represented by “polynomials” in Boolean algebra. It is shown that certain parts of the multiple output problem for such circuits may be reduced to a single output problem whose inputs are equal in number to the sum of the numbers of inputs and outputs in the original problem. A particularly simple reduction may be effected in the case of two outputs. Various techniques are described for simplifying Boolean expressions, called “+ polynomials,” in which the operation “exclusive or” appears between terms. The methods described are particularly suitable for use with an automatic computer, and have been tested on the Illiac. An unexpected metric relationship is shown to exist between the members of certain classes of “+ polynomials” called “nets.” This relationship may be used for constructing error-detecting codes, provided the number of bits in the code is a power of two. View full abstract»

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  • 2. A function generator for the solution of engineering design problems

    Page(s): 34 - 38
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    The solution of nonlinear engineering design problems demonstrates the need for a special function generator. The generator described in this paper satisfies this need. The basic components of the unit are discussed and the forms of functions which can be generated are shown. Accuracy is estimated by comparison of an oscillogram with the calculated curves. It is concluded from tests on the system that the function generator is a valuable aid in the handling of nonlinear design problems. View full abstract»

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  • 3. Design of triode flip-flops for long-term stability

    Page(s): 14 - 26
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    Reliable electronic circuit design must account for the parameter variations over the normal life of components to insure satisfactory operation. An analytical design method is derived for an Eccles-Jordan triode flip-flop in which the “worst” condition of voltage and component tolerances conditions are assumed that assures satisfactory operation for normal conditions. The method of analysis is to divide the flip-flop circuit into separate parts, write appropriate equations, and solve them simultaneously. The design method results in the best configurations of component values, regardless of what tube may be used, and actually specifies characteristics which-the tube should have, as well as the expected life of the tube in terms of maximum plate resistance. View full abstract»

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  • 4. A computer for flaw plotting

    Page(s): 73 - 75
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    Ultrasonic vibrations provide the only known physical means for the non-destructive examination of thick sections of dense materials. The basic method is simple; the equipment is relatively inexpensive, and there is no hazard to operating personnel. Ultrasonics will not completely supplant the older, established techniques of radiographic, magnetic, or dye inspection methods, but it will do inspection jobs which cannot be done by any of these methods. The most commonly used ultrasonic inspection method at the present time is the “contact” method, where the transducer is pressed directly against the surface of the part to be inspected. This is not a method readily adapted to mechanized scanners. The mechanized scanner proceeds in an orderly manner, and avoids the repetitive scanning generally required by the manual method to assure complete coverage. View full abstract»

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  • 5. Electrical delay lines for digital computer applications

    Page(s): 5 - 13
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    A survey of existing lumped parameter and distributed parameter delay lines has shown that their maximum. storage capacity is about 23 pulses and 15 pulses respectively regardless of total delay time. An analysis of pulse transmission through distributed delay lines indicates that dissipation in the inductive elements is the chief factor limiting storage capacity. A method is proposed for decreasing this dissipation through the use of high-Q nickel zinc ferrites around straight conductors for inductive elements. View full abstract»

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  • 6. A time-sharing analog multiplier

    Page(s): 11 - 17
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    This article describes the design of a high speed electronic analog computing circuit which easily lends itself to time-sharing applications. By making use of a special high accuracy electronic switch and circuitry carefully designed to be independent of tube characteristics, it was possible to achieve a full-scale accuracy of better than 0.2 per cent over a wide range of input values. The unit described was built to carry out 400 complete multiplications and divisions in one second. View full abstract»

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  • 7. Professional group on electronic computers system organization of the DYSEAC

    Page(s): 1 - 10
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    The DYSEAC is a complete general-purpose high-speed digital computer utilizing the same basic electronic circuit elements as those in SEAC. In the DYSEAC, however, these basic building blocks have been organized into a more powerful system for controlling and responding to auxiliary devices. Communication between these auxiliary devices and the DYSEAC (or between the DYSEAC and the persons operating it) can take place at any time, on a completely unscheduled basis, at the instigation of either the computer or the external world, or both acting jointly. The System features which enable such impromptu interchanges of information to occur are described in this paper. View full abstract»

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  • 8. The editor

    Page(s): 1
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    Readers of the PGEC Transactions who regularly scan the not-so-fine print of the inside cover may have noticed the name of R. E. Meagher newly listed as the Editor in the June issue. Since the appointment was not settled until June 22nd, this was the fastest news coverage so far in the short history of the Transactions. The purpose of the last-minute change in the cover was to inform potential authors of the new editorial address. Unfortunately, we could not also make a more formal announcement in that short a time. View full abstract»

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  • 9. An improved reading system for magnetically recorded digital data

    Page(s): 22 - 25
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    In magnetic recording of pulses, whether on drum or tape, the resulting flux pattern is affected by proximity of adjacent pulses. The best defined region is that adjacent to the maximum. In reading, the signal is the derivative of the flux. In the best defined region, this is close to a straight line passing through zero when the flux is a maximum. The slope of the curve at the zero changes sign with change of pulse polarity. A new method of reading is described which examines the signal from the head for such transitions from positive to negative or reverse as indications that a positive or negative pulse had been recorded. This is done by gating the inverted signal with the delayed signal for positive pulse reading and the inverse of this for reading negative pulses. Besides providing sharply defined outputs, this method permits reading both positive and negative pulses from a single channel without interference or ambiguity. Examples are given for using this facility for checking purposes and for storage of two types of data in a common channel. View full abstract»

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  • 10. A digital voltage encoder

    Page(s): 25 - 28
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    A two-channel voltage encoder having a sampling rate of 40 numbers/second in each channel has been designed for use in a data reduction system. The data are recorded on single-channel magnetic tape in the form of 10-digit binary numbers with an accuracy of ± 0.1 per cent. The range of input voltage is 0 to 1 volt and may be lowered to 0 to 10 mv through the use of chopper amplifiers. This lower range of input voltage covers the voltages generated by analog transducers commonly employed to measure temperatures, pressures, flow rates, and thrusts. View full abstract»

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  • 11. A new method of generating functions

    Page(s): 29 - 34
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    As a result of a pressing need for function generators, a new method of function generation has been developed. The underlying principle of this function generator is the application of ordinary pulse techniques in such a way as to produce a function. The simplicity of design, the high accuracy attainable, the simple type of construction are the outstanding features of this general-purpose function generator. In order to compare this new type of function generator with those presently being used, three important types are discussed. These generators are of the general-purpose, electric and photoelectric types; other comparable electromechanical types are excluded.1 View full abstract»

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  • 12. Symbolic programming

    Page(s): 10 - 15
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    Automatic calculators can be programmed to interpret programs which have been written with symbolic instead of actual addresses. This method allows the calculator to assume much of the clerical burden which must otherwise be borne by the programmer. View full abstract»

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  • 13. Review section

    Page(s): 41 - 54
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    It is the intention of this section to review articles that have been published since January 1, 1953, and to publish eventually reviews of all books pertaining to the computer field. All articles and books reviewed are numbered sequentially for each year; where known, the Universal Decimal Classification number is also given. The editors wish to express their gratitude to the reviewers who, through their efforts, make this section possible. View full abstract»

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  • 14. A transistorized pulse code modulator

    Page(s): 7 - 12
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    A pulse code modulator is described in which transistors are the only active circuit components. The functions of quantizing and encoding the signal are performed entirely by semiconductor diodes, using transistor amplifiers where necessary to increase the signal level. The readout is obtained from a set of “and” gates, each gate having as one of its inputs an output from the encoding system, and as the other input, a pulse obtained from a time delay circuit to assure sequential operation. The system produces a three digit binary code at a sampling rate of 5,000 cps. View full abstract»

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  • 16. Digital techniques in analog systems

    Page(s): 23 - 29
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    This paper discusses analog computation where the analog components consist of digital elements. Pulse rate is the quantity used to represent the data. Such computation systems may have many advantages over present analog techniques. The various components necessary to produce a complete computation system are described. Several examples of the use of these components to solve specific problems are shown. View full abstract»

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  • 17. System design of the SEAC and DYSEAC

    Page(s): 8 - 23
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    In the course of developing the system plans for the DYSEAC and the SEAC, certain standard methods and procedures were evolved for producing a large-scale digital computer design. These standard procedures cover, first, the development of system specifications, second, the development of functional plans, and finally the development of wiring plans. The later stages of these procedures are reducible to sequences of simple steps, capable of being systematically formulated in explicit terms. The similarity between these procedures and many of the data-processing procedures commonly being executed by present-day computers suggests that, with further development of these design techniques, the wiring plans for new computer systems might well be produced by existing digital machines. View full abstract»

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  • 18. Accuracy of an Analog Computer

    Page(s): 12 - 18
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    1. To determine how accurate the computing components representing a given variable have to be, assume that they constitute one more piece of measuring equipment which must handle the data before it is fed into an ideal computer. 2. In general, the components of an analog computer must have individual accuracies consistent with the measuring equipment available to the group it belongs to. 3. The static accuracy of an operational amplifier may be measured simply by observing the grid voltage in a closed-loop connection as the output is swung through its full range at some low frequency (Fig. 2). Phase shift may be measured simply (Fig. 3), but usually does not play an important part in establishing limits of performance for the computer. 4. Integrator random drift may be measured simply, but is only one cause contributing to integrator error. Account should be taken of the grid deviations measured in the static test above, or else drift measured about a number of non-zero output levels. 5. The effect of integrator drift is to limit the computing time. Required computing time and highest required frequency are determined directly for real-time simulation. In other computing, one may be traded for the other, so long as the product R remains constant. R is the number of cycles of the highest frequency contained in the longest time. Two computers may be compared by comparing their R's; comparing drift rates, computing times, or maximum frequencies alone is not valid. View full abstract»

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  • 19. Logic, discovery, and the foundations of computing machinery

    Page(s): 2 - 7
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    This paper describes the logical nature of computing machines in terms of languages and the types of problems that can be solved by logical operations on languages. The problem of discovery in mathematics and empirical science is discussed, and an “inductive” machine is described which would be able to formulate hypotheses, modify them in the light of new experience and eventually discover the laws of a very simple universe. View full abstract»

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  • 20. High density digital recording system

    Page(s): 60 - 72
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    The numerous economic uses of magnetic recording today bear witness to the scope and quality of the development in recent years on the media, transducers, kinematics, circuits, and systems involved. View full abstract»

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  • 21. Operating experience with UNIVAC SYSTEMS

    Page(s): 33 - 46
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    In December 1951, at the joint AIEE/IRE Computer Conference held in Philadelphia, several papers were given which discussed the performance of a single UNIVAC SYSTEM during its first eight months of operation. Although only eight months have passed since that performance summary was given, a much greater effective length of time has passed because three more UNIVAC SYSTEMS have been put into operation since then, and their records together with those of the first system constitute many more months of operation. This paper, therefore, forms an extension of the earlier paper in which we have the good fortune of being able to confirm a number of the predictions and estimates mentioned in the earlier work. View full abstract»

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  • 22. Multidimensional magnetic memory selection systems

    Page(s): 25 - 32
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    Many investigators have for several years been studying the use of rectangular loop magnetic cores as memory elements. It seems profitable at this time to examine, from a dimensional point of view, the various selection systems which have been developed, and to find the relations between their operating principles. View full abstract»

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  • 23. Applications of CRC-105 decimal digital differential analyzer

    Page(s): 19 - 24
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    In the two years since the first digital differential analyzer was put in operation, it has been the complexity of filling and operating such machines, rather than any difficulty in coding them for a problem, that has constituted the main impediment to convenience and efficiency in their use. In filling some hundred-odd binary digits, one at a time, for each integrator information, the possibility of error is great. For instance, let us look at the binary number View full abstract»

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  • 24. A digital computer for airborne control systems

    Page(s): 2 - 5
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    A digital computer has been developed for use in airborne control systems. This application presents many problems. The computer must be small, light weight, and very reliable. It receives its input signals from instruments in the rest of the system. These signals are of the “analogue” continuous type and must be converted into the discrete electric signals used in the computer. The problems of analogue-digital conversion are problems in the measurement of the physical quantities that define the state of the system and in the transformation of the results of these measurements into digital signals. The digital numbers representing the input quantities are processed by the computer which performs in real time the computations corresponding to the mathematical representation of the control problem. The results of these calculations are numbers representing the signals used to control the system. These output numbers are converted into the analogue type signals used in the control operations. View full abstract»

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  • 25. An Analog-to-Digital Converter

    Page(s): 5 - 7
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    A shaft position to binary number converter suitable for use as an input device for a digital computer is described. The basic component of the converter is a binary mechanical revolution counter having an output in the form of voltages or pulses on parallel lines representing, in the binary number system, the quantity stored in the counter. Ambiguities are eliminated by a novel method of internal switching. The effects of backlash are discussed and shown to be negligible. View full abstract»

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Aims & Scope

This Transactions ceased publication in 1954. The current retitled publication is 

IEEE Transactions on Computers.

Full Aims & Scope