The Development of an Interactive Videodisc System

The thesis traces the development of interactive videodisc from origins based on early automatic machines through large-scale computer assisted learning (CAL) to microcomputer-based multi-media CAL. A comprehensive discussion of the interactive videodisc medium is provided, in terms of its features, advantages, problems, authoring and production processes, and educational applications. The requirements for interactive systems, and essential elements of video and videodisc technology are described. A relatively low-cost demonstration interactive videodisc system is developed in three phases, based on a BBC 'B' microcomputer and a Pioneer LD1100 videodisc player. In the first phase, software interfacing routines are developed in assembly language to control the player from the versatile interface adaptor (VIA) of the BBC micro. The signal control codes are based on a pulse code modulated format with uni-directional synchronous transmission. The interfacing routines are linked to, and driven by, a Basic program which provides full manual control of all player functions using the microcomputer keyboard. In the second phase, the interfacing routines are further extended to provide control linkage for interactive video application programs. Using a pilot videodisc, these Basic programs demonstrate interactive video techniques, including still frame access and the presentation of video sequences and sub-sequences. In the third phase, the application programs are converted to the authoring language, Microtext. The assembly language interfacing routines are developed into a corresponding Microtext extension command module. A mixer/genlock unit is used to provide graphics overlay of video still frames. An evaluation of the demonstration system is provided, in terms of developmental difficulties, its hardware and software features and capabilities, and its potential as a base for further suggested research work