Moving computing off the desktop is not simply an exercise in making computers mobile; it also requires that user interfaces become mobile. A moving user is engaged in activities other than pointing and typing. In this case a user interface must sense user intent indirectly. Being away from the desktop means being out of reach of a mouse or a keyboard. The user interface must accept direct input from alternative sources. Both direct and indirect user input will employ new hardware devices. They will be compact, unobtrusive, wirelessly interconnected, and self-powered. Their design represents an engineering challenge, but the richness of an off-the-desktop user interface using these devices is limited only by the laws of physics and our own imagination.

Turner Whitted is a senior researcher in Microsoft Research's hardware devices group. He has been an adjunct professor of computer science at the University of North Carolina at Chapel Hill since 1983 as well as a cofounder and director of Numerical Design Limited. Prior to that he was a member of the technical staff in Bell Labs' computer systems research laboratory. He earned BSE and MS degrees in electrical engineering from Duke University and a PhD from North Carolina State University. He is an Associate Editor-in-Chief of IEEE Computer Graphics and Applications, was papers chair for SIGGRAPH 97, and is an ACM Fellow.