Over forty years ago, Vannevar Bush articulated his vision of a “Memex” machine: “associative indexing, … whereby any item may be caused at will to select immediately and automatically another” [Bush 45]. In the sixties, Engelbart [Engelbart, English 68] built collaborative systems to provide idea structuring and sharing. Nelson [Nelson 81] coined “hypertext” and proposed world-wide networks for publishing, linking, annotating and indexing multiple versions of documents. With increasing numbers of research projects, papers, panels and conferences, and commercially available systems (e.g. Notecards by Xerox, Guide by Owl and HyperCard by Apple) in recent years, hypertext may be an idea whose time has finally come — or at least a phenomenon not to be ignored.

We describe a prototype electronic encyclopedia implemented on a powerful personal computer, in which user interface, media presentation, and knowledge representation techniques are applied to improving access to a knowledge resource. In itself, an electronic encyclopedia is an important information resource, but this work also illustrates the issues and approaches for many types of electronic information retrieval environments. In the prototype we make dynamic use of the structure and semantics of the text articles and index of an existing encyclopedia, while experimenting with other forms of representation, such as simulation and videodisc images. We present a long-term vision of an intelligent user-interface agent; summarize previous work related to futuristic encyclopedias, electronic books, decision support systems, and knowledge libraries; and outline current and potential research directions.