Computing and Information Systems - Theses

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    Program instrumentation for the detection of software anomalies
    Price, David Andrew ( 1985)
    This thesis examines the automated detection of program errors through the insertion of software instruments into the source to flag anomalies at run-time. Anomalies are located using data flow analysis and pointer checking. Explicit state variables are eliminated using the address and size of an object as keys to an implicit state variable. Expressions are functionally instrumented, that is, instrumented without decomposition. Dead definitions are characterized by a new statement-based dead-on-all-paths criterion. Inefficient definition anomalies are flagged for live definitions which are dead on most paths. The handling of objects whose parts are in many states is elucidated. The utilization of reference-only states to detect parameter anomalies for certain languages is proposed. The pointer range error and the accompanying concept of ‘base’ are invented. All of these innovations are original contributions to the field. The software tool DDF was written by the author to apply the above ideas to the C programming language.
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    Communications subsystem support for multimedia workstations
    Barry, Matthew Edmund ( 1993)
    Multimedia is becoming the buzz word of the 1990s. Personal computers with the capability to display video, reproduce sound and present high resolution graphics are becoming affordable, if not cheap. We present a model for the next generation of these systems: the multimedia workstation. The multimedia workstation's central feature is its ability to communicate at high speed with other computers, not just multimedia workstations, in widely dispersed places. We discuss the expected capabilities of the workstation and the functionality of the networks that will make the workstation possible. Two main types of network to provide interconnection for the multimedia workstation are identified: a heterogeneous network of networks and a homogeneous telecommunications network. The cost of the multimedia workstation suggests that it cannot be designed as simply a video telephone. Instead it must be a versatile work support tool. Video conferencing will be a central facility; but a range of tools to support collaborative work are also needed. The communication requirements of these new applications are used to assess the current generation of communication subsystems. Several areas of weakness are identified. A variety of solutions to the problem areas are suggested, including new operating system paradigms, new protocols, and extensive hardware support for the higher level of communications processing. It is concluded that a combination of the solutions will be required for the multimedia workstation to fulfill its potential.