An overview of the PARCTAB ubiquitous computing experiment

Abstract

The PARCTAB system integrates a palm-sized mobile computer into an office network. The PARCTAB project serves as a preliminary testbed for Ubiquitous Computing, a philosophy originating at Xerox PARC that aims to enrich our computing environment by emphasizing context sensitivity, casual interaction and the spatial arrangement of computers. This pa- per describes the Ubiquitous Computing philosophy, the PARCTAB system, user-interface issues for small devices, and our experience in developing and testing a variety of mobile applications. Although computers are becoming ever more common in appliances such as VCRs, mi- crowave ovens, and personal digital assistants, they remain largely isolated from one another and from more powerful desktop and laptop machines. We believe that in the future many computers will provide more valuable services in combination than they can in isolation. Ideally, many kinds of specialized machines will work together via networks to let users ac- cess and control information, computation and their physical and electronic environments. In the Computer Science Laboratory (CSL) at Xerox PARC we have established a num- ber of research projects to explore this vision, which we call Ubiquitous Computing. This paper presents the results of the PARCTAB project, an experiment intended to clarify the de- sign and application issues involved in constructing a mobile computing system within an office building. The P ARCTAB system provides a useful testbed for some of the ideas of the Ubiquitous Computing philosophy, which is described briefly in the next section. The system is based on palm-sized wireless PARCTAB computers (known generically as "tabs") and an infrared communication system that links them to each other and to desktop com- puters through a local area network (LAN). Although technological and funding limitations forced us to make numerous compromises in designing the PARCTAB hardware, the system, as described in Section 3, meets most of our design goals. Likewise the small size and low resolution of the PARCTAB displays requires an innovative user interface design to allow efficient text entry and option selection. Our solutions are presented in Section 4.