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The history of digital computers represents a twofold development toward the common goal of harnessing “electronic energy” to solve human problems. On the one hand we have the hardware designers producing faster, cheaper, more versatile computers to execute larger, more complex programs. On the other hand we have the software designers generally producing faster, cheaper, and more versatile languages, compilers, operating systems, and application software with which to program these larger, more complex problems. It is only recently that timesharing and interactive systems have begun to bridge the hardware-software generation gap. This paper describes a system which is intended to eliminate the gap by providing a computer which directly executes a powerful language - APL - in a highly efficient manner. The programmer and machine communicate entirely in APL with a fully interactive timesharing operating system integral in the design. In particular this paper focuses on the execution aspects of the computer and relates results obtained by emulating the main processor to conventional computer approaches.

This paper surveys record automatic optimization methods which either have found or should find useful application in the optimal design of microwave networks by digital computer. Emphasis is given to formulations and methods which can be implemented in situations when the classical synthesis approach (analytic or numerical) is inappropriate. Objectives for network optimization are formulated including minimax and least pth. Detailed consideration is given to methods of dealing with parameter and response constraints by means of transformations or penalties. In particular, the formulation of problems in terms of inequality constraints and their solution by sequential unconstrained minimization is discussed. Several one-dimensional and multidimensional minimization strategies are summarized in a tutorial manner. Included are Fibonacci and Golden Section search, interpolation methods, pattern search, Rosenbrock's method, Powell's method, simplex methods, and the Newton-Raphson, Fletcher-Powell, and least squares methods. Relevant examples of interest to microwave circuit designers illustrating the application of computer-aided optimization techniques are presented. The paper also includes a classified list of references.

1. Introduction. The purpose of this article is to present a revised version of an early paper by the author on a register transfer, logic design language and its application to the design of early microprogrammable computer. This paper [1] as an invited paper at an IRE was presented originally at an IEEE meeting held at the Moore School of the University of Pennsylvania, early in 1957. It is being published here in the open literature for the first time in order to present to a wider audience this approach to computer design in its original form.

In setting the stage for the papers which follow, there is discussion in this paper of some problems of terminology concerning multiple-access, on-line, interactive man-computer systems. It presents three viewpoints from which to examine man-computer interaction.

The advent of fast rise-time pulse techniques and their increasing importance brought on by high-speed microminiature circuits and the computer industry has resulted in an increased demand for pulse transformers of various types. The basic idea of constructing transmission line type transformers has been known and used for a number of years. However, such devices have not gained widespread usage, partly because their existence is not well known, but largely because of a lack of basic understanding of their operating principles in terms of elementary fundamentals as well as their capabilities and limitations. The purpose of this paper is twofold. One aim is to develop in step-by-step fashion the basic ideas of transmission line transformers from ordinary transmission line theory. The subject will be approached from the point of view of pulse response rather than ac excitation as is usually the case. Both impedance transformers and balanced-to-unbalanced (balun) transformers, including inverters, will be considered with physical insights into their operation. Several fundamental concepts will be developed and explored in detail (without mathematics), since they have a strong bearing on practical applications. The second purpose is to present new information and pulse measurements which will be useful in the design and applications of such devices, showing their capabilities and hitherto unexplored limitations, as derived from the fundamental concepts. Thus, this paper is partly supplementary to other published work and partly new work with the goal of providing a convenient fundamental understanding of these devices and their inherent potential and shortcomings. Although the intention is not to give a detailed design procedure, some approximate calculations and discussion of significant design criteria are included.

This paper discusses reliability aspects of a modular multiprocessor currently under development by the Naval Air Systems Command. The operating system, or executive, of this computer may be implemented in various ways. These include a totally software "floating executive," one dedicated to a specific processor, or an executive consisting of special-purpose hardware. The objections to hardware executives, especially for avionic applications, include a supposed degradation in system reliability. This paper shows that under certain conditions this degradation need not occur.

The application of electromechanical mass storage devices to computers is rapidly increasing in importance. Mass storage units are being assigned key general systems functions and are basic to many developing applications such as time sharing, communication, and on-line processing. In this paper, the characteristics of typically available hardware in the drum, disk-file, and tape-strip categories are discussed. Next, the most important applications of mass storage devices are reviewed. The special considerations in the design of computer systems which use mass storage are outlined. Commonly used and certain important proposed techniques of file organization and processing are then described. The paper concludes with a discussion of the technology used, some aspects of control unit design, and future possibilities in both hardware and software. Major challenges to designers of future hardware are identified as reduction of the cost per bit of removable media, economical devices with storage capacities larger than 109bits, and a solution to the dilemma of increasing access time with increasing storage capacity.

This paper discusses the ILLIAC IV computer and its application to seismic signal-processing problems. ILLIAC IV, now being fabricated by the Burroughs Corporation, will be operational at the University of Illinois' Computer Science Department in 1970. ILLIAC IV is an array of 256 coupled high-speed digital computers; as such, it has the capacity to execute algorithms 256 times faster than present-day computers. Achievement of large speedup factors, however, is dependent upon "structuring" an algorithm into groups of (nominally, 256) identical computations. As an aid to the programmer, the Tranquil language is being designed with certain common statements, such as matrix operations, prestructured to provide for the parallel execution of code on many pieces of data. These, as well as other aspects of the ILLIAC IV system and the Tranquil language, are described in the first part of this paper. The second part of the paper discusses the structuring of common signal-processing algorithms, such as beam forming, convolution, and fast Fourier transform for ILLIAC IV parallel computation. It is shown that, in a great variety of situations, the full speedup factor, 256, can be obtained.

A comprehensive technical survey of Soviet switching theory and its applications to the logical design of digital systems reveals that, despite considerable activity (763 papers and books), the average state of the art in the U.S.S.R. is somewhat behind that in the U.S. However, there are a large number of noteworthy contributions, particularly in those aspects of the field dealing with complexity estimates of switching networks, synthesis of multiterminal circuits, the selection of logical primitives (building blocks), and certain minimization problems. This paper evaluates the Soviet position through June, 1964, compares it with that in the West, and summarizes the significant Soviet technical contributions. Recommendations are offered for initiating research in the United States in several special problem areas in switching theory.

During the past two years development has been initiated on several large-scale automatic digital computing machines, both in this country and abroad. The present paper is concerned with the over-all organization of one such machine. A logical division of the machine into four major components is described, and the machine performance is interpreted in terms of these component functions. The electronic techniques used to accomplish the storage, transmission, and arithmetic manipulation of numbers, together with certain methods used for control of the computer, are briefly discussed. Although the paper is concerned with the design of a particular machine, it is felt that the design problems and engineering techniques are applicable to most large-scale computing machines.

This paper describes the application of reliability calculation techniques presented in a companion paper [1] to actual power system networks. A digital computer program to facilitate reliability calculations is described, and a comparison of calculated and observed reliability on an actual system is presented.

Many papers have been written about the reflected binary system and it is well known in the computer field for analog-to-digital conversion. The method used in creating this system may be extended to systems of bases other than two. It is the purpose of this paper to carry this extension to its logical conclusion. The author describes how reflected systems of different bases may be composed. The equations for translating between the conventional and reflected systems are then derived. It is also demonstrated how the reflected binary system is a special case of reflected number systems and how the general case simplifies for the reflected binary case.

This paper contains some applications of an elementary study of unate truth functions. One application is a method of deciding when a truth function is linearly separated, i. e., is expressible as a linear polynomial inequality in its arguments (letting 1 represent truth and 0 represent falsity). Other applications are to contact nets and to rectifier nets. Much of the material of this paper, although not in print, is well known to some logicians and switching theorists. Nothing from the first three sections is original.

This paper discusses various strategies and techniques used for editing two-dimensional programs or text and for automatic type-composition of conventional mathematical expressions. The techniques may be used for input prepared on a typewriter that is on-line to a computer or that generates off-line machine-sensible documentation, such as punched paper tape. These techniques, with minor modification, may also be used with a keyboard-controlled cathode ray tube as an input device. Methods of driving a special typewriter in the preparation of composed text can be extended for photocomposition or for a high-speed printer with a special character set. The basic algorithms for the regeneration and internal storage of the two-dimensional document, input in an arbitrary character-by-character order, are discussed, as are other basic techniques for recognizing and parsing two-dimensional mathematical forms and symbols. Illustrations show applications to the automatic composition of mathematical tables and to computer-assisted typing of mathematical text using a newly-designed typewriter terminal (see Fig. 8 of text).

A network containing switches is equivalent to a number of networks that differ in the values of their components, in the arrangement of the components, or in both respects. When analyzing or synthesizing such a network, one may treat each different network by itself, and then combine the results. This paper describes a method by which the different aspects of a switchable network may be treated simultaneously. The mathematics by which the network is treated is a combination of ordinary field algebra (complex numbers) and Boolean algebra. The mathematical foundation is first laid out, then interpreted in terms of switchable network elements. The paper is concluded with some examples of analysis and synthesis of switchable networks.

Obtaining a cost-effective teleprocessing network is postulated on efficient utilization of the communication links and processing equipment. A variety of line-sharing devices and procedures are commonly used for this purpose. The functional, economic, and application aspects of frequency-division multiplexing (FDM), synchronous time-division multiplexing (STDM), asynchronous time-division multiplexing (ATDM), message switching concentration (MSC), and line (or circuit) switching techniques are discussed. The motivations for line sharing stem from economies of scale in the cost of bandwidth and from the traffic smoothing effect which such devices produce when serving a large terminal population characterized by unscheduled requests for service. The discussion of these techniques includes a detailed contrast between multiplexing and concentration, two terms which are often (and unfortunately) used synonymously. It is shown that FDM and STDM are examples of conventional multiplexing, whereas message switching and line switching usually illustrate concentration. ATDM is shown to be a hybrid line-sharing scheme embodying certain features of both concepts. Thus it is often referred to as statistical multiplexing. The first part of the paper is devoted to a functional explanation of the various concepts referenced above. The balance of the paper is concerned with applications and systems-design considerations involving multiplexing and concentration techniques. The application section focuses on important economic factors pertaining to the selection and use of the various methods. The role of line-sharing devices in contemporary common-carrier and end-user networks is also considered. The economic and technical aspects of these contrasting application environments are emphasized and illustrate the multiplicity of uses for line-sharing devices. The concluding portion of the paper includes a discussion of system-design considerations. This section illustrates precisely how the decision to use multiplexers or concentrators in a typical computer-communication network is implemented. Various techniques for geographically positioning multiplexers and concentrators to minimize total costs are presented. The use of one of these procedures is demonstrated using a typical design problem as a case study.

The Automatic Route Control System (ARCS) is a self-contained on-board system that directs the operation of a conventional motor vehicle over predetermined routes and controls activities (such as the delivery or pickup of items) performed along the route. In effect, the system continuously measures the vehicle's location coordinates, compares these with the route coordinates, and then issues audio, visual, and/or printed instructions appropriate to the location. The system also detects driver errors and prescribes corrective action. The routes to be followed and the actions to be taken are defined on interchangeable magnetic tape cartridges, which may be updated daily or as required from a computerized central file. ARCS enables a driver to operate efficiently over a complex route without reference to maps or lists and without prior knowledge of the route. It also eliminates tedious manual report preparation because computer-ready data for route accounting can be acquired on a magnetic tape cartridge. Although applicable to most types of operations carried out over routes that can be defined in advance, the prototype application is for the delivery of newspapers. Installed in a van with paper throwers stationed at special windows on each side, the system signals each thrower with a tone through headphones at the proper time to throw papers to individual subscribers while driving through residential areas at 15-30 mi/h.

Project Whirlwind is a high-speed computer activity sponsored at the Digital Computer Laboratory, formerly a part of the Servomechanisms Laboratory, of the Massachusetts Institute of Technology (MIT) by the US Office of Naval Research (ONR) and the United States Air Force. The project began in 1945 with the assignment of building a highquality real-time aircraft simulator. Historically, the project has always been primarily interested in the fields of real-time simulation and control; but since about the beginning of 1947 most of its efforts have been devoted to the design and construction of the, digital computer known as Whirlwind I (WWI). This computer has been in operation for about 1 year and an increasing proportion of project effort now is going into application studies. Whirlwind I was designed for use in control and simulation work such as air traffic control, industrial process control, and aircraft simulation. Various design and synthesis issues are presented. [Note: Discussion of this paper was combined with that of the following paper: "Evaluation of the Engineering Aspects of Whirlwind I."]

The development of an approach by which frequency and duration indices can be computed for interconnected systems was illustrated in Part I of this paper entitled "Mathematical Analysis". Equations were developed for a system connected to one or to more than one other system. These equations have been incorporated in a general computer program for generating capacity reliability evaluation in single and interconnected systems. This portion of the paper entitled "System Applications" illustrates the numerical application of these general concepts.

The paper reports on augmenting human problem solving capability in the day-to-day work in management or science through provision of information in a large integrated file with split second response to demands for data or program execution. A number of such systems have been developed. However, the description is in terms of the latest system developed at the University of Pennsylvania. In the first part, the paper deals with tbe Multilist technique for mass storage embedded in a system for remote consoles. Console services, a high level query language and interpreter for the query language, and a highly structured file organization are among the special subsystems described. The second part is devoted to illustrations of usages describing a number of the applications which can be concurrently serviced within the system. These include: an automatic library catalog, to illustrate storage and retrieval functions, and inventory management, to illustrate large scale management functions.

In general, the trend toward telemetry systems of increased flexibility and versatility for aerospace vehicles has yielded unacceptable power and processing efficiencies and questionable reliabilities. This paper describes the concepts, organization, and areas of application of a core-memory-programmed telemetry system which has been specifically developed, in its entirety, to provide the versatility required for aerospace vehicular applications and environments. It is felt that this versatility has been achieved, since the telemeter can reasonably be applied to dataprocessing requirements in such diverse areas as deep-space probes, orbiting spacecraft, or avionic data systems. Although format generation is its primary mode of operation, modular expansion of the basic system permits the expanded telemeter to perform as an integral datacompression system. The paper also describes the development of a laboratory model of this versatile telemetry system, which has been constructed to physically implement the various system functions described herein.

Automatic interpretation of electrocardiograms is a particular example of the application of digital computers to medical diagnosis; this paper describes our experience with a new approach involving pattern recognition techniques. The program employs a multiple adaptive matched filter system with a variety of normalization, weighting, comparison, decision, modification, and adapting operations. The flexibility of the method has permitted study of effects of experimental variations of these operations on the pattern classification process to simulate human interpretation of electrocardiograms more closely. These programs have been successfully applied to actual electrocardiograms from cardiac patients. These researches in application of computer pattern recognition techniques to the automatic interpretation of electrocardiograms have been undertaken because they join together three fields of great interest. First, an example of artificial intelligence or a self-organized system is represented by the adaptive filter memory, together with the related decision operations. Second, we consider our program to be a model of complex sensory discrimination and use our intuition of human psychology as a guide when selecting one of several possible program mechanisms to overcome temporary obstacles. Third, the automation of medical diagnosis is a rapidly developing and promising field contributing to medical progress. This paper pays particular attention to the third of these objectives. The present state of computer analysis of electrocardiograms is mainly one of orthogonalization of the spatial vector, point recognition to separate the various component waves, parameterization, in one case via Fourier techniques, and then statistical matrix analysis.

An important objective of software test programs is to identity, "high-risk" components. This paper focuses on one method which can be applied to identify high-risk software components, the use of a classification tree with an established software metrics set. The selected examples of high-risk software components are those modules which are most likely to induce errors in the target operational system, and those software components which will require the most effort in the development process. The associated metrics are software reliability and productivity. This paper describes the methodology utilized by the US Army in the application of classification trees for analysis of software metrics data. A detailed example is provided with a step-by-step procedure for construction of a classification tree for software metrics analysis. >

This paper reviews the state of the art of methods and techniques suitable for use in the automatic optimization of microwave circuits by digital computer. A number of significant recent developments in the rapidly developing area of computer-oriented circuit theory and design which may be directly applied to high frequency or distributed circuits are emphasized. A fairly extensive classified bibliography on optimization methods and on some applications, primarily in the microwave area, is included. The principal aim of this paper is to bring the microwave circuit designer up to date with developments in computer-oriented optimization methods and techniques and their application to microwave circuit design. To achieve this, the state of the art is reviewed in a tutorial manner, highlighting the talk with material taken from a variety of recent research papers, published during the last year or so. Promising areas for future work are indicated. A fairly extensive classified bibliography on optimization methods and on some applications, primarily in the microwave area, concludes the paper. Papers and books not necessarily in the microwave area are referenced if it is felt that the subject matter is, nevertheless, relevant. The first question that a microwave circuit designer might have is what material should he read to convince himself that he can solve a wide variety of design problems using optimization techniques. Five articles [1]-[5] are referenced under the heading of Reviews of Network Optimization which should probably be found most useful.

A store and forward message switching system, made up of duplexed 16-bit computers, fixed head discs (FHDs), moving head discs (MHDs), and multiline controllers (MLCs) is described. The paper discusses the area of application for a system of this type, and the equipment configuration and operation of the subject system. The paper concludes with a discussion of the redundancyswitchover aspects of the system and the system size.

This paper presents a synthesis method of ternary digital systems by means of a threshold algebra. The method is based on the fact that the K operations of any ternary function can be expressed as threshold operations on a set of functions called midterms. Such midterms can be easily generated from the outputs of the ternary multivibrators described by the authors in a previous paper [4].

The process of frequency synthesis is the step-by-step approximation to the normalized output frequency. In this paper, three different approximation algorithms are briefly discussed, namely continued fractions, Cantor products, and Engel series. Their common disadvantage is their uniqueness; it is shown that this difficulty may be overcome by application of the new general approximation theorem, but the solution can be provided only by computer. Approximation errors are generally small, sometimes smaller than 1 × 10-12. The advantage of modified Cantor products or Engel series algorithms is the possibility of standardizing the hard ware of frequency synthesizers, particularly if the IC technology and the use of off-the-shelf circuits is emphasized.

Applications of computers in the planning of power system generation, transmission, and distribution are surveyed. Following a brief description of significant developments in the growth of these applications over the 22 years since the first published paper, the stages in planning (policy, standardization, outline, and detail design) and the mathematical techniques which can be applied to the numerical solution of quantifiable problems arising in these stages are outlined. The greatest concern is with the technical and economic studies commonly used in the major areas of planning, i.e., load forecasting, assessment of generation capacity and mix, transmission and distribution network development. Approaches using simulation and optimization techniques are described. Reference is made to developments in corporate planning.

In this paper we discuss the issues involved in implementing an automatic computer voice response system which is capable of serving up to ten independent output channels in real time. The system has been implemented on a Data General NOVA- 800 minicomputer. Individual isolated words and phrases are coded at a rate of 24 000 bits/s using a hardware adaptive, differential pulse-code modulation (ADPCM) coder, and stored on a fixed-head disk as a random access vocabulary. By exploiting the features of ADPCM coding, it is possible to create and edit automatically a vocabulary for the system from an analog tape recording of the spoken entries, with minimal operator intervention. To provide ten simultaneous output lines of speech which are independent of each other required the use of an efficient scheduling algorithm. Such an algorithm was provided by the computer manufacturer in their real-time multitasking system which was part of their Fortran software. Thus almost all the programming required to implement this real-time system was in Fortran, thereby providing flexibility and ease in making changes in the system. Initial applications of the voice response system are in computer aided voice wiring, automatic directory assistance, and experiments on speaker verification, but the system is sufficiently modular to adapt readily to other applications.

The main objective of this paper is to give a survey of recent automatic optimization methods which either have found or should find useful application in the area of computer-aided network design. Huang's family of algorithms for unconstrained optimization is reviewed. The Fletcher method and the Charalambous family of algorithms for unconstrained optimization, which abandon the "full linear search," are presented. Special emphasis is devoted to algorithms by Bandler and Charalambous on least pth and minimax optimization which can be readily programmed and used. Due to work by Bandler and Charalambous, it is shown how constrained minimax problems can be solved exactly as unconstrained minimax problems by using a new approach to nonlinear programming. The application of minirnax optimization on the design of lumped-distributed active filters, problems for future investigation, and a select list of references are also included.

This paper describes a library of computer field programs available for design investigations during the development of high-voltage switchgear equipment. The emphasis is on recent developments to a general-purpose multidielectric field program suitable for solving practical field problems in two dimensions or in three dimensions with one axis of symmetry. These developments include an improved presentation of printout data, automatic drawings of computed equipotentials, and accurate calculation of gradient values for practical systems. A quadratic fit method and finite-difference techniques to compute gradient values are discussed together with associated accuracies. Finally, examples are given of the application of this numerical technique to high-voltage switchgear design.

In this computer era, most engineers have benefitted tremendously from use of computers. This paper explains the application of computer-aided design to the remote control transmitter for the Magnavox deluxe color T. V. remote control system.

A historical development of mechanical and electronic differential analyzers as well as the significant developments in simulation techniques are discussed. Present-day application of modern analog and hybrid computers to electric power systems are presented. Included are the simulation of electric machines, static converter drives, transmission lines, and dc power systems. Special-purpose analog and hybrid computers are also discussed briefly. The material presented in this paper should enable an informed evaluation of the capabilities of analog and hybrid computers in the analysis of power system problems.

This paper claims that the increasing heterogeneity of the community of conmputer users poses a challenge to psychologists and human factors researchers. There follows a brief discussion of why this challenge apparently has not yet evoked a strong response. Three problems, or problem areas, are identified as being particularly in need of human factors research. These are (1) the development and evaluation of conversational languages, (2) the determination of how the use patterns adopted by users depend on system characteristics, and (3) the description, or modelling, of man-computer interaction.

The time-shared computer is a powerful tool for assisting in the solution to many problems. Four examples are given which illustrate its use: 1) starting transients of an induction motor, 2) dc motor with current limit control, 3) parameter optimization of a speed regulator for a dc shunt motor, and 4) inverse Laplace transform. A brief discussion of each example is given, and typical results are described. Details are not given since that would require a separate paper for each example.

Computer-driven cathode-ray tube (CRT) displays are becoming an important means of on-line man-machine communication, particularly for graphical input/output in laboratory investigations of computer-aided design techniques. Their operation, however, often requires so much of the computational resources of the associated computer that they are not yet considered economic or practical for general industrial use. This paper discusses the systems engineering problems in designing and using display systems, with emphasis on the hardware-software tradeoffs. As an example, a display specifically developed for computer-aided design applications is described which has unusual special-purpose computing capabilities for dynamic picture manipulations, including rotation, scaling, and translation of 3-dimensional images. it is concluded that there is much work ahead, and that the proper hardware-software organization for these complexes of computers, communication links, terminals, and men is a fertile field for the systems engineer.

A sequential machine is defined to be linear if its next-state function and output function are linear transformations from their domains (vector spaces) to their ranges (also vector spaces). It is shown that this definition is equivalent to those given by other authors. Based on this definition, a set of necessary and sufficient conditions for the flow table of a sequential machine to be linear is obtained. Many properties of the flow table of a linear sequential machine are found, and in many cases they form very simple tests for the linearity of a flow table. A general procedure for testing the linearity of a flow table is established. This procedure, including the coding of the states, inputs, and outputs, either ends with a linear realization of the flow table with the minimum possible numbers of state variables, input variables, and output variables, or detects that such a linear realization for the flow table is impossible. The type of sequential machine considered in this paper is deterministic and synchronous, and both Moore model and Mealy model are studied in detail. The linearity of incompletely specified sequential machines is also discussed.

This paper describes the AN/ASN-9?a miniaturized, dead-reckoning navigational computer. The design premises which allow its size reduction are explained; problem solution equations are given; and system functional diagrams are presented. Some of the techniques employed in achieving its small size are described, as are certain areas of its application.

The study of speech communication and speech processing systems by simulation on a digital computer, and the design and physical implementation of these systems with discrete components, require a detailed knowledge of the elements known as digital filters. Following a definition of the digital filter, the different areas in which digital filters have been used in speech research and communication are explored. The basic theory relating to the design and application of digital filters is reviewed. Attention is given not only to the use of a general purpose computer to mechanize the simulation but also to the design of special purpose hardware to realize the digital filter as either an actual communication system component or as a laboratory research element. Following a discussion of several of the numerical problems that can arise in the design and utilization of digital filters, the paper concludes with a cursory look at some of the advantages and disadvantages of the use of digital filters in speech processing systems.

General Purpose Digital Computers are now making their appearance in industrial plants. For the most part, they do not merely mechanize tasks previously handled by humans but make possible an entirely new era in control of complicated processes. Industrial Control Computers are now being designed for such applications. This paper discusses in basic terms the characteristics and performance features of Industrial Computers, and how they can increase process profitability. Computer Speed, Memory Capacity, Kind of Memory, Mechanical Design, Programming Features, Reliability and other specifications are related to requirements of Industrial Control. A typical application analysis is explained through use of a high-speed tin plate line as an illustrative example. Several suggestions are offered as an aid in the writing of better purchase specifications. Currently about three years are needed to go from first conception to an operating Industrial Computer installation. A discussion is given of the many tasks to be completed by user and supplier in this process.

The rapidly increasing capability of the digital process control computer permits the economic solution of many electric utility system operating problems in a more accurate and timely manner. In this paper, the extension of the application area from the field of economic dispatch of generation to more sophisticated functions of system security is traced. Other related problems in the area of operations planning, operations control, and operations accounting are also reviewed. The requirements of communication systems to provide remote input data to the process computer are discussed, and the close interrelation of business and process computers is recognized. Information display is shown to play a very significant part in providing output to the system operators for further action. Concurrent with the developments in hardware have been significant advances in analytical techniques to encompass the increasing number of problems of system operation. These are reviewed in relation to the two major concerns, system security and system economics. An integrated information and control system may he achieved today for business, engineering, and system operation as a result of significant developments in hardware and in problem solution concepts. The optimum application of these improved equipments and analytical tools requires a total systems viewpoint in relation to both hardware and software.

This paper presents a procedure for stability analysis by the Tsypkin Locus method of an unforced control system with relay-type actuator. The procedure was written with special attention given to the minimization of the computation time; thus it may be efficiently executed on a minicomputer. The procedure and a flow chart are presented and the case of a nuclear reactor control is given as an example.

The designers of the Apollo G&N system adopted a conservative but flexible design philosophy. In this paper the development of the guidance computer is described which typifies the application of the design approach throughout the development of the system. The computers have demonstrated a mean-time-between-failure (MTBF) of four to five times that predicted. The success of the design approach has thus been shown by the observed reliability of the system.