Toby J. Teorey – Communications of the ACM

Research and Advances Aug 1 1989

ER model clustering as an aid for user communication and documentation in database design

Entity-relationship clustering promotes the simplicity that is vital for fast end-user comprehension, as well as the complexity at a more detailed level to satisfy the database designer's need for extended semantic expression in the conceptual model.

Computing Applications

Author Archives

Research and Advances Apr 1 1988

Cost/benefit analysis for incorporating human factors in the software lifecycle

New software engineering techniques and the necessity to improve the user interface in increasingly interactive software environments have led to a change in traditional software development methods. Methodologies for improvement of the interface design, an overview of the human factors element, and cost/benefit aspects are explored.

Computing Applications

Research and Advances Jun 1 1978

General equations for idealized CPU-I/O overlap configurations

General equations are derived for estimating the maximum possible utilization of main storage partitions, CPU and I/O devices under different conditions in an idealized CPU-I/O overlap model of multiprogrammed computer systems. The equations are directly applicable to any configuration consisting of sets of identical CPU's, I/O processors, main storage partitions and user tasks. Examples are provided to illustrate the use of the equations to compute effective processing time per record and expected timesharing response time under both balanced and unbalanced resource utilization conditions.

Computing Applications

Research and Advances Mar 1 1972

A comparative analysis of disk scheduling policies

Five well-known scheduling policies for movable head disks are compared using the performance criteria of expected seek time (system oriented) and expected waiting time (individual I/O request oriented). Both analytical and simulation results are obtained. The variance of waiting time is introduced as another meaningful measure of performance, showing possible discrimination against individual requests. Then the choice of a utility function to measure total performance including system oriented and individual request oriented measures is described. Such a function allows one to differentiate among the scheduling policies over a wide range of input loading conditions. The selection and implementation of a maximum performance two-policy algorithm are discussed.

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