The Xerox PARCTAB

Introduction

The PARCTAB system is a research prototype developed at Xerox PARC to explore the capabilities and impact of mobile computers in an office setting. This research is part of PARC's Ubiquitous Computing research program.

The PARCTAB system consists of palm-sized mobile computers that can communicate wirelessly through infrared transceivers to workstation-based applications. Take a look at the hardware specifications or a picture gallery .

A small number of basic principles and assumptions have driven our design:

Extreme portability.
The device is designed to be carried or worn at all times, much like a pager. It's size, weight, and features are intended to promote casual, spur of the moment, computing. For example, it has no power switch and instead automatically turns itself on when a person starts interacting and off after a person has finished interacting.
Constant connectivity.
The system assumes the palm-top unit is always connected to the network infrastructure.
Location reporting.
The location of each PARCTAB is always known to system software.

The system designers specifically avoided addressing certain issues, such as intermittent connectivity and disconnected operation, that would be of concern in a product. Restricting the system capabilities in this way let us conserve time and money without affecting the project's main goal which is to investigate location-based and casual computing. The most significant advantage of assuming constant connectivity is that the device can use the computing power on the network. That is, instead of relying entirely on local processing the device interacts with programs running on a user's desktop system. An equivalent device with a desktop-speed processor would have been heavier, larger, and more costly to development.

History

The PARCTAB has been under development since early 1992. In March 1993 we released the first system for general (non-project) use:

Fourteen transceivers were installed in CSL offices, commons, tea area, and library during the week of March 15, 1993. First (non tabteam) PARCTABs given to Brent Welch on Thursday March 25, 1993, and Berry Kercheval, Dan Swinehart and Mark Weiser on Friday March 26, 1993. By the first of April 1993 there were twenty-five transceivers and twenty tabs assigned to Norman Adams, Pavel Curtis, Rich Gold, David Goldberg, Berry Kerceval, Bill Schilit, Dan Swinehart, Doug Terry, Roy Want, Mark Weiser, Brent Welch and others. -- Release Notes

By early 1994 the system had stabilized and the software entered a maintenance stage where development was limited to bug fixes and applications. At this time there were 41 lab members using tabs:

Version 7.0 of the system was released on Monday 18th April 1994 with an ``opening'' party in the CSL commons. There were 50 transceivers in CSL and 10 in Europarc. In total there were 41 tabs released to CSL including 10 new style 128K tabs. -- Release Notes

Publications

The PARCTAB Ubiquitous Computing Experiment
Roy Want, Bill N. Schilit, Norman I. Adams, Rich Gold, Karin Petersen, David Goldberg, John R. Ellis and Mark Weiser.

The PARCTAB Mobile Computing System
Bill N. Schilit, Norman Adams, Rich Gold, Michael Tso and Roy Want.

An Infrared Network for Mobile Computers
Norman Adams, Rich Gold, Bill N. Schilit, Michael Tso and Roy Want.

Related Publications

: Responsive office environments, by Scott Elrod, Gene Hall, Rick Costanza, Michael Dixon, and Jim des Rivieres. CACM, 36(7):84--85, July 1993. In Special Issue, Computer-Augmented Environments.; Tcl/Tk for a Personal Digital Assistant, by Karin Petersen. In Proceedings of the USENIX Symposium on Very High Level Languages, Pages 41-54, Santa Fe, NM, October 1994. USENIX Association.; A System Architecture for Context-Aware Mobile Computing, by Bill N. Schilit. PhD Dissertation, Columbia University, New York, NY, 10025. May 1995.; Context-Aware Computing Applications, by Bill N. Schilit, Norman I. Adams, and Roy Want. In Proceedings of the Workshop on Mobile Computing Systems and Applications, Pages 85-90, Santa Cruz, CA, December 1994. IEEE Computer Society.
(ftp://ftp.parc.xerox.com/pub/schilit/wmc-94-schilit.ps 119K); Disseminating Active Map Information to Mobile Hosts, by Bill N. Schilit and Marvin M. Theimer. IEEE Network, 8(5), pages 22-32, September/October 1994, IEEE Computer Society.
(ftp://ftp.parc.xerox.com/pub/schilit/AMS.ps.Z 102K); Customizing Mobile Application, by Bill N. Schilit, Marvin M. Theimer and Brent B. Welch. In Proceedings of the USENIX Symposium on Mobile and Location-independent Computing, pages 129-138, Cambridge, MA, August 1993. USENIX Association.
(ftp://ftp.parc.xerox.com/pub/schilit/usmlic-93-schilit.ps.Z 32K)
: Active Badges and Personal Interactive Computing Objects, by Roy Want and Andy Hopper. IEEE Transactions on Consumer Electronics, 38(1):10-20, February 1992.
(ftp://ftp.cam-orl.co.uk:/pub/docs/ORL/tr.92.2.ps.Z 53K)
: The Active Badge Location System, by Roy Want, Andy Hopper, Veronica Falcao, and Jonathan Gibbons. ACM Transactions on Information Systems, 10(1):91-102, January 1992.
(ftp://ftp.cam-orl.co.uk:/pub/docs/ORL/tr.92.1.ps.Z 49K); The Computer for the 21st Century, by Mark Weiser. Scientific American 265(3):94-104, September 1991.
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: Some Computer Science Issues in Ubiquitous Computing, by Mark Weiser. CACM, 36(7):74--83, July 1993.
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Bill Schilit & Roy Want
Thu Apr 13 17:19:56 PDT 1995

Last updated on April 14, 1995 by BNS