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Research and Advances Jun 1 1983

Flowcharts versus program design languages: an experimental comparison

An experiment was performed to assess the relative merits of program design languages (PDLs) and flowcharts as techniques for the development and documentation of detailed designs for computer programs. The use of a PDL by a software designer, for the development and description of a detailed program design, produced better results than did the use of flowcharts. Specifically, the designs appeared to be of significantly better quality, involving more algorithmic or procedural detail, than those produced using flowcharts. In addition, flowchart designs exhibited considerably more abbreviation and other space-saving practices than did PDL designs, with a possible adverse effect on their readability. When equivalent, highly readable designs were presented to subjects in both PDL and flowchart form, no pattern of short-term or long-term differences in comprehension of the design was observed. No significant differences were detected in the quality or other properties of programs written as implementations of the designs. Subjective ratings indicated a mild preference for PDLs. Overall, the results suggest that software design performance and designer-programmer communication might be significantly improved by the adoption of informal PDLs rather than flowcharts as a standard documentation method for detailed computer program designs.
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Research and Advances Jun 1 1983

Power, politics, and MIS implementation

Theories of resistance to management information systems (MIS) are important because they guide the implementation strategies and tactics chosen by implementors. Three basic theories of the causes of resistance underlie many prescriptions and rules for MIS implementation. Simply stated, people resist MIS because of their own internal factors, because of poor system design, and because of the interaction of specific system design features with aspects of the organizational context of system use. These theories differ in their basic assumptions about systems, organizations, and resistance; they also differ in predictions that can be derived from them and in their implications for the implementation process. These differences are described and the task of evaluating the theories on the bases of the differences is begun. Data from a case study are used to illustrate the theories and to demonstrate the superiority, for implementors, of the interaction theory.
Research and Advances Jun 1 1983

A general purpose data entry program

Simulations constitute an important family of computer applications in science and engineering. To perform each simulation run, it is usually necessary to provide extensive data specifying the parameters of the simulation as well as data which support the calculation models involved. We have designed a program and a file structure that provides a method for convenient data entry, and creates and edits data files according to specifications contained in a separate file that serves as a template. By providing different templates, the same program can be made to serve numerous applications. The structure of the data files allows a degree of flexibility difficult to achieve using conventional database systems.
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Research and Advances Jun 1 1983

A real-time garbage collector based on the lifetimes of objects

In previous heap storage systems, the cost of creating objects and garbage collection is independent of the lifetime of the object. Since objects with short lifetimes account for a large portion of storage use, it is worth optimizing a garbage collector to reclaim storage for these objects more quickly. The garbage collector should spend proportionately less effort reclaiming objects with longer lifetimes. We present a garbage collection algorithm that (1) makes storage for short-lived objects cheaper than storage for long-lived objects, (2) that operates in real time—object creation and access times are bounded, (3) increases locality of reference, for better virtual memory performance, (4) works well with multiple processors and a large address space.
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Research and Advances May 1 1983

Prototyping interactive information systems

Applying prototype-oriented development processes to computerized application systems significantly improves the likelihood that useful systems will be developed and that the overall development cycle will be shortened. The prototype development methodology and development tool presented here have been widely applied to the development of interactive information systems in the commercial data processing setting. The effectiveness and relationship to other applications is discussed.
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Research and Advances May 1 1983

DOCUMENTS: an interactive online solution to four documentation problems

An adequate delivery system for user documentation addresses the problems of easy access, versatile publication, convenient administration, and good document quality. At the National Magnetic Fusion Energy Computer Center the DOCUMENT program helps solve these problems by providing a high level of service through strategies that can readily be exported to other contexts. Dividing machine-readable documents into keyword windows permits fully online, subject-oriented access to all passages. An adaptive, three-tier user interface extends flexible viewing control to novices and experts alike. DOCUMENT also supports online subject, title, and date catalogs, and provides on-demand output of hardcopy and microfiche. Several other document delivery systems are compared with DOCUMENT, and all have more rigid human interfaces, more structural display units for text, or more cumbersome output options.
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Research and Advances May 1 1983

Math proficiency: a key to success for computer science students

A computer science aptitude predictor was administered to students enrolled in a first technical course in computer science to determine potential for success. The study revealed significant differences in the scoring between students who withdrew from the course and those students who did not. The causes for the differences all related to the students' mathematical background: high school performance, previous computer science education, and the number of college mathematics courses taken.
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Research and Advances May 1 1983

The dynamics of software project scheduling

Software project scheduling is one of the major problem areas faced by software project managers today. While several quantitative software project resource and schedule estimation methods have been developed, such techniques raise some important, but as yet unresolved, dynamic issues. A systems dynamics (SD) approach is used to analyze several key dynamic software project scheduling issues.
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Research and Advances May 1 1983

ACL: a language specific for auditors

Audit software is essential for accountants. The software should be written to consolidate the audit support functions into a common language for management information systems (MIS). ACL (Audit Command Language) is a prototype language for designing a feasible interactive conversational language for auditing purposes.
Research and Advances May 1 1983

A general-purpose algorithm for analyzing concurrent programs

Developing and verifying concurrent programs presents several problems. A static analysis algorithm is presented here that addresses the following problems: how processes are synchronized, what determines when programs are run in parallel, and how errors are detected in the synchronization structure. Though the research focuses on Ada, the results can be applied to other concurrent programming languages such as CSP.
Research and Advances Apr 1 1983

Composing letters with a simulated listening typewriter

With a listening typewriter, what an author says would be automatically recognized and displayed in front of him or her. However, speech recognition is not yet advanced enough to provide people with a reliable listening typewriter. An aim of our experiments was to determine if an imperfect listening typewriter would be useful for composing letters. Participants dictated letters, either in isolated words or in consecutive word speech. They did this with simulations of listening typewriters that recognized either a limited vocabulary (1000 or 5000 words)or an unlimited vocabulary. Results suggest that some versions, even upon first using them, could be at least as good as traditional methods of handwriting and dictating. Isolated word speech with large vocabularies may provide the basis for a useful listening typewriter.
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Research and Advances Apr 1 1983

Design rules based on analyses of human error

By analyzing the classes of errors that people make with systems, it is possible to develop principles of system design that minimize both the occurrence of error and the effects. This paper demonstrates some of these principles through the analysis of one class of errors: slips of action. Slips are defined to be situations in which the user's intention was proper, but the results did not conform to that intention. Many properties of existing systems are conducive to slips; from the classification of these errors, some procedures to minimize the occurrence of slips are developed.
Research and Advances Apr 1 1983

Using formal specifications in the design of a human-computer interface

Formal specification techniques are valuable in software development because they permit a designer to describe the external behavior of a system precisely without specifying its internal implementation. Although formal specifications have been applied to many areas of software systems, they have not been widely used for specifying user interfaces. In the Military Message System project at the Naval Research Laboratory, the user interfaces as well as the other components of a family of message systems are specified formally, and prototypes are then implemented from the specifications. This paper illustrates the specification of the user interface module for the family of message systems. It then surveys specification techniques that can be applied to human-computer interfaces and divides the techniques into two categories: those based on state transition diagrams and those based on BNF. Examples of both types of specifications are given. Specification notations based on state transition diagrams are preferable to those based on BNF because the former capture the surface structure of the user interface more perspicuously. In either notation, a high-level abstraction for describing the semantics of the user interface is needed, and an application-specific one is used here.
Research and Advances Apr 1 1983

Job and health implications of VDT use: initial results of the Wisconsin-NIOSH study

Magnitudes and correlates of stress were investigated among 248 office workplace VDT users and 85 nonuser counterparts using field survey and objective physical measurement techniques. Other than a tenuous indication of increased eyestrain and reduced psychological disturbances among users, the two groups were largely undifferentiated on job-attitudinal, affective, and somatic manifestations of stress. However, aspects of working conditions were judged less favorably by VDT users. Stress mechanisms were much the same for both groups, involving psychosocial as well as physical environmental job attributes. For VDT users, the chair and workstation configuration were particularly important predictors of musculo-skeletal disturbances, as were corrective eyewear use and ambient lighting for visuo-ocular disturbances.
Research and Advances Apr 1 1983

The evaluation of text editors: methodology and empirical results.

This paper presents a methodology for evaluating text editors on several dimensions: the time it takes experts to perform basic editing tasks, the time experts spend making and correcting errors, the rate at which novices learn to perform basic editing tasks, and the functionality of editors over more complex tasks. Time, errors, and learning are measured experimentally; functionality is measured analytically; time is also calculated analytically. The methodology has thus far been used to evaluate nine diverse text editors, producing an initial database of performance results. The database is used to tell us not only about the editors but also about the users—the magnitude of individual differences and the factors affecting novice learning.
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Research and Advances Mar 1 1983

Remote office work: changing work patterns in space and time

Remote work refers to organizational work that is performed outside of the normal organizational confines of space and time. The term telecommuting refers to the substitution of communications capabilities for travel to a central work location. Office automation technology permits many office workers to be potential telecommuters in that their work can be performed remotely with computer and communications support. This paper examines some behavioral, organizational, and social issues surrounding remote work, particularly work at home. An exploratory study was conducted of 32 organizational employees who were working at home. Important characteristics of jobs that can be performed at home were: minimum physical requirements, individual control over work pace, defined deliverables, a need for concentration, and a relatively low need for communication. The individuals who worked at home successfully were found to be highly self-motivated and self-disciplined and to have skills which provided them with bargaining power. They also made the arrangement either because of family requirements or because they preferred few social contacts beyond family.
Research and Advances Mar 1 1983

Speeding up an overrelaxation method of division in Radix-2n machine

For normalized floating point division, digital computers can take advantage of a division process that uses an iterative multiplying operation instead of repeated subtractions. An improvement of this division process by using accelerating constants in the overrelaxation has previously been proposed. Multiplication by a chosen accelerating constant accelerates the process of generating accurate digits of a quotient in division. We propose a further improvement by generalizing the accelerating constants in the overrelaxation method. Two benefits resulting from this improvement promise to yield faster division in digital computers.
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Research and Advances Mar 1 1983

A tree convolution algorithm for the solution of queueing networks

A new algorithm called the tree convolution algorithm, for the computation of normalization constants and performance measures of product-form queueing networks, is presented. Compared to existing algorithms, the algorithm is very efficient in the solution of networks with many service centers and many sparse routing chains. (A network is said to have sparse routing chains if the chains visit, on the average, only a small fraction of all centers in the network.) In such a network, substantial time and space savings can be achieved by exploiting the network's routing information. The time and space reductions are made possible by two features of the algorithm: (1) the sequence of array convolutions to compute a normalization constant is determined according to the traversal of a tree; (2) the convolutions are performed between arrays that are smaller than arrays used by existing algorithms. The routing information of a given network is used to configure the tree to reduce the algorithm's time and space requirements; some effective heuristics for optimization are described. An exact solution of a communication network model with 64 queues and 32 routing chains is illustrated.
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Research and Advances Mar 1 1983

On the modeling of parallel access to shared data

A model is constructed of a database that can be accessed and modified concurrently by a number of users, and an approximate solution is presented. The resource allocation policies considered involve dynamic acquisition of entities and locking; deadlock is avoided by limiting the number of consecutive attempts to acquire a particular entity. The accuracy of the approximation is evaluated by simulations. Several generalizations aimed at improving the practicality of the model are described.
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Research and Advances Feb 1 1983

On the synthesis of decision tables

Synthesis of decision rules, each depicting a part of a decision process, is necessary in order to know the decision process in total perspective and to validate the consistency and the correctness of the decision logic. This paper proposes a method to synthesize a set of decision tables, each one of them representing a part of the decision logic, and thus serves as a tool for the system analyst in the system design phase.
Research and Advances Feb 1 1983

The computational metaphor and quantum physics

Concurrent computational systems, viewed as sets of cooperating processes, are shown to have close analogies in the world of quantum physics. In particular, analogies exist between processes and particles, between a process' state and a particle's mass, between a process'state changes and a particle's velocity, and between interprocess communications and particle interactions. This view allows the application in the computational world of special relativity theory, the uncertainty principle, the law of conservation of momentum, and many of particle physics' fundamental results. This paper describes the basic analogy and some fundamental results. It is the authors' belief that new insights into a computational processes will be gained as the analogy is developed and vice versa. It is conceivable that established results of the computational sciences may contribute to a new understanding of some of the problems of physics. Other process-oriented sciences, such as biology, economics, and psychology, could also benefit from such development.
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