General Purpose Digital Computer Research Articles

An interactive digital computer system for radiotherapy treatment planning.

Abstract A small general purpose digital computer has been programmed to produce dose distributions for external beam radiotherapy. The system is simple to use; it allows radiotherapists and technicians direct access to the computer through a keyboard and other controls. Anatomical data—outline, treatment volume and critical organs—are traced with a pointer on a movable arm and stored in the machine. As the tracing proceeds, a copy of the anatomical structure appears on the screen of a storage oscilloscope. Symbols representing X-ray beams are then super-imposed on the screen and, using potentiometers, moved in position and angle relative to the outline. When suitably positioned, the combined dose distribution for up to six beams is calculated and this takes about two seconds per beam. The desired isodose levels are then selected and they appear on the screen, each in about half a second. If the dose distribution is unsatisfactory, beam positions, sizes, wedge angles and weights can be changed. In about 1...

An On-Line Spectrofluorimeter System for Rapid Collection of Absolute Luminescence Spectra

A spectrofluorimeter system has been developed which uses an on-line general purpose digital computer to both collect and correct fluorescence and luminescence spectra; no servosystems or complex analog circuitry are employed. Spectra are represented by a series of up to 500 individual data points, each of which is, in turn, the average of 16 samplings of the signal photomultiplier. The signal produced by a reference photomultiplier is also collected and used to make corrections appropriate to the type of spectra being collected. Wavelength drive is accomplished with a reversible stepping motor driven by commands from the computer; thus the wavelength position can be automatically and precisely controlled by the computer without recourse to cumbersome mechanical components. Corrections to collected spectra are made in real time on the basis of correction factors derived from fluorescence standards or a standard lamp. The complete system can collect a full spectrum (500 points) in 8 sec, average the results of any number of automatically repeated scans, and furnish the operator with both corrected and uncorrected spectra on either a wavelength or a wavenumber scale. In addition, the data can be retained on punched paper tape or presented graphically in a format acceptable for publication. Details of the system are presented with examples of its performance.

General-Purpose Equipment for Human Factors Research

The small laboratory that engages in a variety of human factors experiments must rely on equipment that can be easily assembled into widely different configurations. This article discusses analog computing units, digital logic modules, and interface and auxiliary equipment as these may be used in the small human factors or behavioral sciences laboratory. A novel use of a desk-top general-purpose digital computer, modified to allow it to serve as “nerve center” for conducting experiments and processing data, is then described.

Electronic Computer Production Management-A New Era

This computer control system in the Pegasus field southwest of Midland, Texas, delegates to a digital computer most of the operational functions normally performed by humans and allows local management to be in contact with the entire operation on a real-time basis. The system has functioned better than anticipated and has effected notable improvements in production operations. Introduction The Pegasus Computer Control System is a highly sophisticated "real-time on-line" electronic system to control producing operations in the Mobil Oil Corp. Pegasus complex. The system, functioning on a Pegasus complex. The system, functioning on a management-by-exception basis, controls wells, gathers all pertinent operating data, checks status, and takes appropriate control action automatically and unattended. It was designed, programed, and installed between Dec., 1965, and Sept., 1968. The Pegasus complex is a six-zone oil and gas field and integrated gasoline plant approximately 22 miles southwest of Midland, Tex. (Fig. 1). Mobil Oil Corp. is the unit operator of the Pegasus Ellenburger, Pegasus Pennsylvanian, Pegasus Spraberry and Pegasus Pegasus Pennsylvanian, Pegasus Spraberry and Pegasus Field Unit No. 3 units, and in addition operates nonunitized San Andres wells. The field encompasses 351 wells (including 40 injection wells) with daily average oil production of 15,500 bbl. The gasoline plant processes 70 MMcf of natural gas per day and produces processes 70 MMcf of natural gas per day and produces 8,000 bbl of NGL per day. Active fluid injection projects are in operation in the Pennsylvanian, projects are in operation in the Pennsylvanian, Ellenburger, and Spraberry reservoirs. Before computer control, the field operations required a force of 36 employees, including supervisory employees, and exclusive of plant personnel. These employees operated, controlled, maintained and reported on Mobil's operations in the Pegasus held. Most of the repetitive operational functions previously performed by humans are now under computer program control, and the field operating force has been reduced by 22 percent. The control system allows local management, using the general-purpose digital computer through the control system, to be in contact with the entire operation instantaneously and simultaneously on a preprogrammed management-by-exception basis. This is similar to talking to all field operators with all the operational answers on a conference telephone call, and being able to assimilate the information instantaneously and take appropriate action immediately. Exceptions are handled by manual entries. The control system has input and output capabilities for on-line direct communication with larger accounting and scientific computer systems. The expanded use of the Pegasus Computer Control System will produce many new intangible benefits that should eventually be greater than the direct operational benefits. Description of the System The Pegasus Computer Control and Data Acquisition System consists of several functional parts as shown in Fig. 2. The system encompasses approximately 1,400 status, 1,400 control, and 1,400 data acquisition points and was designed to allow all prime mover devices to remain as they are when power prime mover devices to remain as they are when power is interrupted. JPT P. 793

INCAS Integrated Navigation and Collision Avoidance System

The integrated navigation and Collision Avoidance System (INCAS) is designed to improve the safety and efficiency of ship operation by increased automation of the navigation and collision avoidance functions. It is intended that the navigator's knowledge and judgment be augmented by the preprogramming of all known information relating to the selected route and by the continuous and automatic assessment of dangers represented by passing vessels and other obstacles to navigation. The system utilizes a general purpose digital computer, which operates as a central processor for the data provided by the shipboard sensors. The information resulting from this integration and computation is displayed to ship personnel in a form which is easily understandable and requires no operator manipulation or calculation; automatic alarms are also provided. The data compilation and computation, coupled with displays and alarms, restores the watch officer to his decision making role and leaves him unburdened to properly ensure the safety of his vessel. Due to system design, the central data processor may be expanded to operate with other sensors to perform additional tasks.

The human auditory evoked response and contingent negative variation in hyperbaric air

The auditory evoked response (AER) and contingent negative variation (CNV) were recorded from thirteen experienced divers, before, during and following an exposure to an increased ambient air pressure simulating a depth in sea water of 91.5 m (300 ft., 10 atm. abs.). Off-line data analysis was accomplished using a LINC 8 General Purpose Digital Computer. The results indicate that the AER was significantly affected at depth, as shown by an average 63.5% ± 4.5 reduction in the N 1P 2 amplitude, whilst the CNV showed no significant changes from controls. The results are interpreted as indicating that the AER and CNV are generated by independent mechanisms. The AER is considered to be attenuated by inhibition exerted during its propagation and passage through the ascending reticular activating system (ARAS). The CNV is considered to be a self propagating phenomenon, initiated by the interaction between the specific, non-specific and associational thalamic nuclei and, as such, to be at least partly independent of the changes assumed to occur in the activity of the ARAS.

A Digital Computer as Process Controller of a 2.2 m Ritchey-Chrétien Telescope

In 1969 a new astronomical institution was founded in the Federal Republicof Germany. This “Max-Planck-Institut für Astronomie” will consist of a central institute at Heidelberg and two observatories, one in the South-East of Spain and one in the Southern hemisphere (possibly in South-West Africa). Each observatory will be equipped with a 2.2-metre Ritchey-Chrétien telescope; these instruments are now under construction at Carl Zeiss, Oberkochen, Western Germany. In addition, a 3.5-metre telescope will be built. A smaller Ritchey-Chrétien telescope of 1.2 m will go into operation next year in Spain. The mirror disks of the 3.5-metre and 2.2-metre telescopes have been ordered from Schott & Gen. at Mainz; they are made of glass ceramic “Zerodur”, a zero-expansion material similar to CerVit. In the operation of the 2.2-metre telescopes and their peripherals, small, general purpose digital computers will be employed.

Compufilms: A computer animation process

Compufilms is a computer-generated animation tech nique developed jointly by Pennsylvania Research Associates Inc. (PRA) and film producer, Stanley Rose. A medium-scale general-purpose digital compu ter (RCA Spectra 70/46) is used to generate display instructions for a Digital Equipment Corporation PDP 8/338 connected as a satellite computer via telephone lines. The DEC 338 CRT display is photographed with a motor-driven motion picture camera having a "single frame" feature. Special effects and color are added at this point. The basic movie generating softwave was written at the Moore School of Electrical Engineering, Univer sity of Pennsylvania, on sponsored projects. The developers have been able to extend the use of this software and combine it effectively with special animation and cinemagraphic processes to create Compufilms. This article describes the system and its operation, and illustrates its use as a practi cal animation process.

On-line computer system in a low-level counting laboratory

A system has been developed at the Weizmann Institute of Science to provide on-line data acquisition and analysis from four independent tritium and 14C experiments. It is based on a small general purpose digital computer (PDP-8/S) and a special interface. The design of the hardware and software was intended to optimize the acquisition and processing functions, and includes an objective data quality evaluation test. Several design and performance problems are discussed. The system resolution is analysed by using the renewal theory.

A Computer-Controlled Infrared Eclipse Telescope

An f/8, chopped, dual beam, gyroscopically pointed telescope has been constructed for use in obtaining infrared (7-13 micro) observations of the spectrum of the thermal emission of the solar corona. The instrument employs a scanning Michelson interferometer with germanium beam splitter and a germanium bolometer operated at 2 K. A small general purpose digital computer is used for experiment control and data processing. The computer, using reference signals from the chopper, controls the position of the moving interferometer mirror (through a stepper motor), and the operation of an A/D converter enabling rapid measurements of the bolometer output to be made. Synchronous detection, necessary to minimize sky background radiation, is accomplished within the computer. The resulting interferograms are stored on magnetic tape for future processing and displayed on an x-y recorder. A fourier transformed spectrum may be generated on operator request in nearly real time.

Computer Programs which Play Music with Microtones

SOLIDAC is a small general-purpose digital computer, built and largely designed by Barr and Stroud Ltd. It was intended for instructional use in Glasgow University. The design dates from 1959, and manufacture was completed in 1963. The computer is wholly transistorised, with ferrite-core storage for 1,024 words of 20 bits, and a basic pulse frequency of 30,000 Hz. Notwithstanding these restrictions of size and speed, SOLIDAC has been programmed to provide for a variety of applications involving directly audible musical output. This is obtained by attaching an amplifier and loudspeaker (conveniently, from a tape recorder) to terminals which are connected to an internal circuit in which a rectangular pulse can occur with a duration of about half a millisecond. The repetition frequency of these pulses can be varied, by suitable programming, to control the pitch of a note; and the number of repetitions can be varied, also, to control the duration. The volume-level of a note is unvarying, and the 'attack' is instantaneous, with liability to a faint clicksound from starting transients. (There is some scope to reduce this by using tone-control facilities.) The notes have a good content of higher harmonics— increasingly so, at lower pitches, but with some progressive reduction of general volume-level—and the timbre is not unlike that of conventional wind or woodwind instruments. Musical expression can be valuably improved by making use of grace-notes or similar decoration, by introducing rubato and rallentando, and by providing small explicit rests, for staccato.

Free-Text Indexing to meet Computers Halfway

part of the idea introduced is presented through the TYPOGRAPHy of this abstract. as OPTICal READers, SPEECH COMPRESsion, external VIDEO-FILE or MICROForm STORage, ANALOG-DIGITal-analog conversion, and free-TEXT SEARCHing are gradually combined with parallel processing COMPUTers, there is a growing need for SOURCE INDEXing and TEXT COMPRESsion of ABSTRACTs or the original full DOCUMENT RECORDs. a methodology is described which will meet these trends as well as shorten human READing time and facilitate BROWSing, SCANning, and INFORMation RETRIEVal within DOCUMENTs themselves. a simple PEDAL SWITCH device is used to bestow efficient functioning of CAPITAL and SMALL LETTERs. the outlined technique can be used in practical applications to speed up INFORMation RETRIEVal by most general-purpose DIGITal COMPUTers, but also implies design concepts for a special-purpose STRING PROCESsor, and units for ALPHABETic INPUT SORTing, WORD-STEM STORage, ASSOCIATive CONCEPT LINKage, and FILE ORGANIZation. in this context ALLOCATion of internal MEMORy and external STORage is discussed. the technical procedure and the rule of thumb for FORMATing may be regarded as a game of SEMANTic OPTIMization within the frame of certain criteria similar to ORIENTal WORD CHAINing such as HAIKU and RENGA. high INFORMation density and ENTROPy reduction is also anticipated while the basic principle is merely practical. GRAMMArless TEXT handling as described is reminiscent of ORWELL's NEWSPEAK in the year 1984.

MATS - The mission analysis and trajectory simulation program

T Mission Analysis and Trajectory Simulation Program (MATS) is a general-purpose digital computer pragram written in FORTRAN IV.' It either has simulated or is potentially capable of simulating such diverse missions as Apollo, Mariner, Surveyor, Tiros, Comsat, Minuteman, and Sentinel. Key points of philosophy underlying the MATS design concept are: a phase-oriented sequencer controls the occurrence of events; the input parameters control the simulation; a bucket concept generalizes and minimizes data storage; and a modularized integrated systems approach permits planned evolution. The phase concept provides the mechanism whereby occurrence of events can be sequenced logically as in real-time situations. A phase is defined as a time interval corresponding to one of a continuous sequence of flight segments. A phase may be of zero duration to simulate an instantaneous inflight or logical event. Phase changes are treated as trajectory discrete points at which variables that affect the vehicle, environment or simulation may be introduced or varied. Examples of phase-oriented trajectory parameters are engine ignition and cutoff, attitude maneuvers or steering algorithms, and environment modifications; phase-oriented simulation parameters include integration method and stepsize control, output requests, logical phase manipulations, and iteration processes. The bucket concept minimizes the input storage requirements by identifying the data by phase, and storing it en masse; as each phase is initiated, the associated data are brought into active memory. The data are stored contiguously, so that no preassigned limits determine the type and volume active during any phase. Figure 1 schematically represents the program structure, which is based on a modular design concept.

A Digital Computer Engineering Laboratory

The course and laboratory discussed in this paper offer students an opportunity to gain realistic experience in the engineering of digital computers. The laboratory provides a sufficient number of logic elements to allow students to construct general purpose digital computers of modest design; only a few assemblies of fixed design are provided. The course progresses from work with basic combinational and sequential circuits through the design and testing of digital subsystems, to a project in which groups of students are challenged to specify, design, test, program, and demonstrate their digital computer. Two years of experience indicate that students are willing to enthusiastically expend a great deal of effort to meet this challenge.

A hardware trigger for temporal indexing of the electrocardiographic signal

A hardware trigger has been constructed to aid in the alignment of successive waveforms in real-time averaging of electrocardiographic signals on a general purpose digital computer. The device minimizes demands on central processor time and core storage while providing accurate time alignment to within plus or minus one sample for analog-to-digital conversion rates in excess of 500 samples per second. The performance of the hardware trigger is analyzed in detail for various types of electrocardiographic signals. The stability of the electrocardiographic signal is also examined.

Impulse Response Determination by Cross Correlation

This paper describes the design of a digital cross correlator and its application in determining the impulse response in linear systems. The output of the cross correlator, which correlates the input and the output of a linear system excited by noise, is the same as the response of the linear system to a pulse which is identical to the noise autocorrelation. The impulse response error is defined as the normalized mean-square deviation of the actual from the true impulse response. A digital computer simulation confirms that the conventional technique yields the same impulse error as the correlation technique, when the width of the input rectangular pulse is equivalent to the width of the noise autocorrelation function. The operation and design of the digital correlator are discussed. An advantage of the specially designed digital correlator over a general-purpose digital computer is to operate in real time without problems of software and storage. The presented experimental and digitally computed results show that the digital correlator can accurately determine the impulse response, even in presence of perturbations. Only the correlation technique allows measurement of system impulse response without disturbing normal operation. Suggestions are made to simplify the design and improve the speed (bandwidth capability).

Machine solutions of light curves of eclipsing binary systems

This paper considers various approaches to the solution of light curves by general-purpose digital computers. Two classes of solutions are defined. The direct methods attempt to arrive at all pertinent eclipse parameters simultaneously. The indirect methods, on the other hand, strive to isolate a specific parameter in terms of which the remaining elements of the eclipse can be determined. Advantages and weaknesses of various methods within these classes are discussed. The major part of the paper is devoted to the discussion of an example of implementing an actual computation. For this purpose the solution of a complete occultation eclipse in terms of the second method of Kopal is chosen. A detailed discussion of the computer programs and operator procedures is included. Typical computations are presented for the YZ Cassiopeiae system. The computer language employed is basic Fortran. In conclusion it is argued that attempts to analyze complex binary systems by indirect methods hold little promise. The writer feels that such systems should be studied by direct methods implemented in terms of computer simulation techniques.

Automatic Data Collection for Mossbauer Effect Spectroscopy

An automatic data collection system for four Mössbauer effect experiments has been implemented by Argonne National Laboratory utilizing a small general purpose digital computer and a special purpose interface. This system, being characteristic of open-loop, on-line systems, permits maximum utilization to be made of interface hardware to fully automate data collection from four simultaneous experiments, while the computer is in a "halt" condition or being utilized for background processing. Extensive consideration was given in the design of this system to achieve the most advantageous balance of hardware and software.

Redundant Measurements in Microwave Research and Development

Capability and accuracy of microwave measuring methods and instruments can be substantially improved by the use of general-purpose digital computers. One of the fruitful applications is concerned with redundant measurements and their evaluation. In a redundant measurement more data are measured than would be necessary for a singular evaluation and the excess information is used to reduce measurement errors. Redundant measurements are advantageous for sophisticated microwave measurements where the final results can be determined only by tedious graphical or numerical transforms of measured data. Redundant measuring methods also can be used to verify network or device models and, to determine the parameters of these models. The evaluation of redundant measurements can be carried out in simple cases by averaging and generally by fitting the hypothetical parameters to the measured data (e.g., by least-square error method) or by using integral transform (e.g., Fourier transform) techniques. Digital computers enable one to make fast and accurate evaluations.

Electrocardiographic interpretation by computer

A program for the automatic interpretation of electrocardiograms using a general purpose digital computer has been under development at the Latter-day Saints Hospital. The analysis is performed using the orthogonal XYZ Franck lead system. This system was chosen in order to reduce the amount of data transmitted and analyzed by the computer. Interpretive statements are made concerning only the QRS and ST-T waves of the electrocardiogram at this time. Development is under way for interpretation of the P wave as well as arrhythmia diagnosis.