The Computer
`for the 2 1 st Century
`
`Specialized elements of hardware and software,
`connected by wires, radio waves and infrared, will be
`so ubiquitous that no one will notice their presence
`
`by Mark Weiser
`
`I
`
`he most profound technologies
`
`are those that disappear. They
`
`weave themselves into the fabric
`of everyday life until they are indistin-
`guishable from it.
`Consider writing, perhaps the first
`information technology. The ability to
`represent spoken language symbolical-
`ly for long-term storage freed informaw
`tion from the limits of individual mem-
`ory. Today this technology is ubiqui-
`tous in industrialized countries. Not
`only do books, magazines and newspa—
`pers convey written information, but so
`do street signs, billboards, shop signs
`and even graffiti. Candy wrappers are
`covered in writing. The constant back-
`ground presence of these products of
`“literacy technology" does not require
`active attention. but the information to
`be transmitted is ready for use at a
`glance. It is difficult to imagine modern
`life otherwise.
`
`Silicon-based information technology,
`in contrast, is far from having become
`part of the environment. More than 50
`million personal computers have been
`sold, and the computer nonetheless re-
`mains largely in a world of its own. It
`
`
`
`
`MARK WEISER is head of the Computv
`er Science Laboratory at the Xerox Palo
`Alto Research Center. He is working on
`the next revolution of computing after
`workstations, variously known as ubiqui-
`tous computing or embodied virtuality.
`Before worlo'ng at PARC, he was a profes-
`sor of computer science at the University
`of Maryland; he received his PhD. from
`the University of Michigan in 1979. Weis-
`er also helped found an electronic pub-
`lishing company and a video arts compa-
`ny and claims to enjoy computer pro-
`gramming “for the fun of it." His most
`recent technical work involved the imple-
`mentation of new theories of automatic
`computer memory reclamation, known
`in the field as garbage collection.
`
`
`
`
`is approachable only through complex
`jargon that has nothing to do with the
`tasks for which people use computers.
`The state of the art is perhaps analo-
`gous to the period when scribes had to
`know as much about making ink or
`baking clay as they did about writing.
`The arcane aura that surrounds per-
`sonal computers is not just a “user in-
`terface” problem. My colleagues and I
`at the Xerox Palo Alto Research Center
`think that the idea of a "personal" com-
`puter itself is misplaced and that the
`vision of laptop machines, dynabooks
`and "knowledge navigators" is only a
`transitional step toward achieving the
`real potential of information technolo-
`gy. Such machines cannot truly make
`computing an integral, invisible part of
`people‘s lives. We are therefore trying to
`conceive a new way of thinking about
`computers, one that takes into account
`the human world and allows the come
`puters themselves to vanish into the
`background.
`
`uch a disappearance is a funda-
`mental consequence not of tech?
`nology but of human psycholo-
`gy. Whenever people learn something
`sufficiently well, they cease to be aware
`of it. When you look at a street sign,
`for example, you absorb its informa-
`tion without consciously performing
`the act of reading. Computer scientist,
`economist and Nobelist Herbert A. Si—
`mon calls this phenomenon ”compil-
`ing”; philosopher Michael Polanyi calls
`it the “tacit dimension"; psychologist
`J. J. Gibson calls it “visual invariants";
`philosophers Hans Georg Gadamer and
`Martin Heidegger call it the ”horizon”
`and the “ready-to-hand”; John Seely
`Brovm of PARC calls it the “periphe-
`ry.” All say, in essence, that only when
`things disappear in this way are we
`freed to use them without thinking and
`so to focus beyond them on new goals.
`
`The idea of integrating computers
`seamlessly into the world at large runs
`counter to a number of presentaday
`trends. “Ubiquitous computing" in this
`context does not mean just computers
`that can be carried to the beach, jun-
`gle or airport. Even the most powerful
`notebook computer, with access to a
`worldwide information network, still
`focuses attention on a single box. By
`analogy with writing, carrying a super-
`laptop is like owning just one very im-
`portant book. Customizing this book,
`even writing millions of other books,
`does not begin to capture the real pow-
`er of literacy.
`Furthermore, although ubiquitous
`computers may use sound and video
`in addition to text and graphics, that
`does not make them “multimedia com-
`puters.” Today’s multimedia machine
`makes the computer screen into a de—
`manding focus of attention rather than
`allowing it to fade into the background.
`Perhaps most diametrically opposed
`to our vision is the notion of virtual re-
`ality, which attempts to make a world
`inside the computer. Users don special
`goggles that project an artificial scene
`onto their eyes; they wear gloves or
`even bodysuits that sense their mo-
`tions and gestures so that
`they can
`move about and manipulate virtual ob-
`jects. Although it may have its purpose
`in allowing people to explore realms
`otherwise inaccessible—the insides of
`cells, the surfaces of distant planets, the
`information web of data bases—virtu-
`al reality is only a map, not a territo-
`ry. It excludes desks, offices, other peo
`ple not wearing goggles and bodysuits,
`weather, trees, walks, chance encoun-
`ters and, in general, the infinite rich-
`ness of the universe. Virtual reality fo—
`cuses an enormous apparatus on simu-
`lating the world rather than on invisibly
`enhancing the world that already exists.
`Indeed, the opposition between the
`
`78
`
`THE COMPUTER IN THE ler CENTURY
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`Reprinted from the September 1991 issue
`
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`and integrating them with other tools has helped researchers
`understand better the eventual shape of ubiquitous comput-
`ing. In conjunction with active badges. live boards can cus-
`tomize the information they dispiay.
`
`UBIQUITOUS COMPUTING begins to emerge in the form of live
`boards that replace chalkboards as well as in other devices at
`the Xerox Palo Alto Research Center. Computer scientists
`gather around a live board for discussion. Building boards
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`WIRED AND WIRELESS NETWORKS link computers and al-
`low their users to share programs and data. The computers
`pictured here include conventional terminals and file serv-
`ers, pocket-size machines known as tabs and page~size ones
`
`known as pads. Future networks must be capable of support-
`ing hundreds of devices in a single room and must also cope
`with deviceseranging from tabs to laser printers or large-
`screen displays—that move from one place to another.
`
`notion of virtual reality and ubiquitous,
`invisible computing is so strong that
`some of us use the term “embodied
`virtuality" to refer to the process of
`drawing computers out of their elec-
`tronic shells. The “virtuality” of com-
`puter~readable data—all the different
`ways in which they can be altered, pro»
`cessed and analyzed—is brought into
`the physical world.
`
`ow do technologies disappear
`into the background? The van-
`ishing of electric motors may
`serve as an instructive example. At the
`turn of the century, a typical workshop
`or factory contained a single engine
`that drove dozens or hundreds of dif-
`ferent machines through a system of
`shafts and pulleys. Cheap, small, effi-
`cient electric motors made it possible
`first to give each tool its own source of
`motive force, then to put many motors
`into a single machine.
`A glance through the shop manual
`of a typical automobile, for example,
`reveals 22 motors and 25 solenoids.
`They start the engine, clean the wind-
`shield, lock and unlock the doors, and
`so on. By paying careful attention, the
`driver might be able to discern when—
`ever he or she activated a motor, but
`there would be no point to it.
`Most computers that participate in
`embodied virtuality will be invisible in
`
`fact as well as in metaphor. Already
`computers in light switches,
`thermo»
`stats, stereos and ovens help to acti—
`vate the world. These machines and
`more will be interconnected in a ubiqui-
`tous network. As computer scientists,
`however, my colleagues and I have fo—
`cused on devices that transmit and dis»
`play information more directly. We have
`found two issues of crucial importance:
`location and scale. Little is more basic
`to human perception than physical jux-
`taposition, and so ubiquitous comput-
`ers must know Where they are. (Today‘s
`computers, in contrast, have no idea
`of their location and surroundings.) If a
`computer knows merely what room it
`is in, it can adapt its behavior in sig-
`nificant ways without requiring even a
`hint of artificial intelligence.
`Ubiquitous computers will also come
`in different sizes, each suited to a
`particular task. My colleagues and I
`have built what we call tabs, pads and
`boards: inch~scale machines that ap-
`proximate active Post-it notes, foot-scale
`ones that behave something like a sheet
`of paper (or a book or a magazine) and
`yard-scale displays that are the equiva-
`lent of a blackboard or bulletin board.
`How many tabs, pads and hoard-size
`writing and display surfaces are there
`in a typical room? Look around you:
`at the inch Scale, include wall notes,
`titles on book spines, labels on con-
`
`trols, thermostats and clocks, as well as
`small pieces of paper. Depending on the
`room, you may see more than 100 tabs,
`10 or 20 pads and one or two boards.
`This leads to our goal for initially de-
`ploying the hardware of embodied virtu—
`ality: hundreds of computers per room.
`Hundreds of computers in a room
`could seem intimidating at first, just
`as hundreds of volts coursing through
`wires in the walls once did. But like the
`wires in the walls, these hundreds of
`computers will come to be invisible to
`common awareness. People will simply
`use them unconsciously to accomplish
`everyday tasks.
`Tabs are the smallest components of
`embodied virtuality. Because they are
`interconnected, tabs will expand on the
`usefulness of existing inch-scale com-
`puters, such as the pocket calculator
`and the pocket organizer. Tabs will
`also take on functions that no comput-
`er performs today. For example, com-
`puter scientists at PARC and other re-
`search laboratories around the world
`have begun working with active badg-
`es—clip—on computers roughly the size
`of an employee ID. card, first devel-
`oped by the Olivetti Cambridge research
`laboratory. These badges can identify
`themselves to receivers placed through-
`out a building, thus making it possible
`to keep track of the people or objects
`to which they are attached.
`
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`In our experimental embodied vir-
`tuality, doors open only to the right
`badge wearer, rooms greet people by
`name, telephone calls can be automati—
`cally forwarded to wherever the recipi-
`ent may be, receptionists actually know
`where people are, computer terminals
`retrieve the preferences of whoever is
`sitting at them, and appointment di—
`aries write themselves. The automatic
`diary shows how such a simple task as
`knowing where people are can yield
`complex dividends: meetings, for ex—
`ample, consist of several people spend-
`ing time in the same room, and the
`subject of a meeting is most probably
`the files called up on that room's dis
`play screen while the people are there.
`No revolution in artificial intelligence is
`needed, merely computers embedded
`in the everyday world.
`My colleague Roy Want has designed
`a tab incorporating a small display that
`can serve simultaneously as an active
`badge, calendar and diary. It will also act
`as an extension to computer screens: in-
`stead of shrinking a program window
`down to a small icon on the screen, for
`example, a user will be able to shrink
`the window onto a tab display. This will
`leave the screen free for information
`and also let people arrange their com-
`puter-based projects in the area around
`their terminals, much as they now ar-
`range paperebased projects in piles on
`desks and tables. Carrying a project to
`a different office for discussion is as
`simple as gathering up its tabs; the as?
`sociated programs and files can be
`called up on any terminal.
`
`he next step up in size is the
`
`pad, something of a cross be
`
`I
`
`tween a sheet of paper and cur-
`rent laptop and palmtop computers.
`Robert Krivacic of PARC has built a
`prototype pad that uses two micro-
`processors, a workstationvsize display,
`a multibutton stylus and a radio net-
`work with enough communications
`bandwidth to support hundreds of de-
`vices per person per room.
`Pads differ from conventional por~
`table computers in one crucial way.
`Whereas portable computers go every
`where with their owners, the pad that
`must be carried from place to place is a
`failure. Pads are intended to be “scrap
`computers“ {analogous to scrap paper)
`that can be grabbed and used anywhere;
`they have no individualized identity or
`importance.
`One way to think of pads is as an anti—
`dote to windows. Windows were invent—
`ed at PARC and popularized by Apple in
`the Macintosh as a way of fitting sev—
`eral different activities onto the small
`space of a computer screen at the same
`
`In 20 years computer screens
`time.
`number of purposes: in the home, vid-
`eo screens and bulletin boards; in the
`have not grown much larger. Computer
`office, bulletin boards, white boards or
`window systems are often said to be
`flip charts. A board might also serve as
`based on the desktop metaphoribut
`an electronic bookcase from which one
`who would ever use a desk only nine
`inches high by 11 inches wide?
`might download texts to a pad or tab.
`Pads,
`in contrast, use a real desk.
`For the time being, however, the ability
`to pull out a book and place it comforta
`Spread many electronic pads around on
`the desk, just as you spread out papers.
`ably on one’s lap remains one of the
`many attractions of paper. Similar 0b—
`Have many tasks in front of you, and
`use the pads as reminders. Go beyond
`jections apply to using a board as a
`the desk to drawers, shelves, coffee ta?
`desktop; people will have to become
`accustomed to having pads and tabs
`bles. Spread the many parts of the many
`on a desk as an adjunct to computer
`tasks of the day out in front of you to
`screens before taking embodied virtu-
`fit both the task and the reach of your
`ality any further.
`arms and eyes rather than to fit the
`limitations of glassblowing. Someday
`Prototype boards, built by Richard
`Bruce and Scott Elrod of PARC, are in
`pads may even be as small and light as
`use at several Xerox research labora—
`actual paper, but meanwhile they can
`tories. They measure about 40 by 60
`fulfill many more of paper’s functions
`inches and display 1,024 X768 blackv
`than can computer screens.
`and—white pixels. To manipulate the
`Yard—size displays (boards) serve a
`
`
`
`
`- The Active Badge _
`his harbinger of inch-scale
`computers contains a small
`microprocessor and an infrared
`transmitter. The badge broad-
`casts theidentity of'its wearer
`and so can trigger automatic
`doors, automatic telephone. for-
`warding and computer displays
`customized toeach person read-
`ing them. The active badge and
`other networked tiny computers .
`- are calEed tabs.
`'
`'
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`
`BATTEFllES
`
`CONTROL
`
`
`Burrow
`
`
`. MICRO- '
`PROCESSOR
`
`-
`
`
`
`INFRARED
`LIGHT-EMITTING
`DiODES
`
`
`
`THE COMPUTER IN THE 2151" CENTURY
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`display, users pick up a piece of wire-
`less electronic “chalk” that can work
`either in contact with the surface or
`from a distance. Some researchers, us—
`ing themselves and their colleagues as
`guinea pigs, can hold electronically nie-
`diated meetings or engage in other
`forms of collaboration around a live
`board. Others use the boards as test-
`beds for improved display hardware,
`new “ch
`” and interactive software.
`For both obvious and subtle rea—
`sons,
`the software that anirnates a
`large shared display and its electron-
`ic chalk is not the same as that for a
`workstation. Switching back and forth
`between chalk and keyboard may in-
`volve walking several steps, and so the
`act is qualitatively different from us
`ing a keyboard and mouse. In addition,
`body size is an issue. Not everyone can
`reach the top of the board, so a Macin-
`toshvstyle menu bar might have to run
`across the bottom of the screen instead.
`We have built enough live boards
`to permit casual use: they have been
`placed in ordinary conference rooms
`and open areas, and no one need sign
`up or give advance notice before us-
`ing them. By building and using these
`boards, researchers start to experience
`
`and so understand a world in which
`computer interaction informally en-
`hances every room. Live boards can
`usefully be shared across rooms as
`well as within them. In experiments
`instigated by Paul Dourish of Euro-
`PARC and Sara Bly and Frank Halasz
`of PARC, groups at widely separated
`sites gathered around boardsieach
`displaying the same imageiand jointly
`composed pictures and drawings. They
`have even shared two boards across
`the Atlantic.
`live boards can also be used as hula
`letin boards. There is already too much
`text for people to read and compre-
`hend all of it, and so Marvin Theirner
`and David Nichols of PARC have built a
`prototype system that attunes its pub-
`lic information to the people reading it.
`Their "scoreboard” requires little or no
`interaction from the user other than to
`look and to wear an active badge.
`Prototype tabs, pads and boards are
`just the beginning of ubiquitous com—
`puting. The real power of the concept
`comes not from any one of these de-
`vices—it emerges from the interaction
`of all of them. The hundreds of proces-
`sors and displays are not a “user inter-
`face" like a mouse and Windows, just
`
`a pleasant and effective “place“ to get
`things done.
`What will be most pleasant and effec-
`tive is that tabs can animate objects
`previously inert. They can beep to help
`locate mislaid papers, books or other
`items. File drawers can open and show
`the desired folderino searching. Tabs
`in library catalogues can make active
`maps to any book and guide searchers
`to it, even if it is off the shelf, left on a
`table by the last reader.
`In presentations, the size of text on
`overhead slides, the volume of the am-
`plified voice, even the amount of am—
`bient light, can be determined not by
`guesswork but by the desires of the lis-
`teners in the room at that moment.
`Software tools for tallying votes in-
`stantly and consensus checking are al-
`ready available in electronic meeting
`rooms of some large corporations; tabs
`can make them widespread.
`
`I I 1he technology required for ubiq-
`
`uitous computing comes in three
`parts: cheap, low-power comput-
`ers that include equally convenient dis-
`plays, software for ubiquitous appli-
`cations and a network that ties them
`all together. Current trends suggest that
`
`
`
`
`
`”an.“
`
`COMPUTER SCRATCHPADS augment the conventional screen
`in this office at the Xerox Palo Alto Research Center. Proto-
`
`type pads are wired to conventional computers; thus far only
`a handful of wireless models have been built.
`
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`the first of these requirements will eas-
`ily be met. Flat-panel displays contain-
`ing 640x 480 black-and—white pixels
`are now common. This is the standard
`size for PCs and is also about right
`for television. As long as laptop, palms
`top and notebook computers continue
`to grow in popularity, display prices
`will fall, and resolution and quality
`will rise. By the end of the decade, a
`1,000 X 800—pixel high—contrast display
`will be a fraction of a centimeter thick
`and weigh perhaps 100 grams. A small
`battery will provide several days of con—
`tinuous use.
`Larger displays are a somewhat dif-
`ferent issue. If an interactive comput—
`er screen is to match a white board in
`usefulness, it must be viewable from
`arm’s length as well as from across a
`room. For close viewing, the density of
`picture elements should be no worse
`than on a standard computer screen,
`about 80 per inch. Maintaining a densi-
`ty of 80 pixels per inch over an area
`several feet on a side implies display-
`ing tens of millions of pixels. The big-
`gest computer screen made today has
`only about one fourth that capacity.
`Such large displays will probably be ex;
`pensive, but they should certainly be
`available.
`
`The large display will require ad-
`vanced microprocessors to feed it. Cen-
`tral-processing—unit speeds reached a
`million instructions per second in 1986
`and continue to double each year. Some
`industry observers believe that this ex-
`ponential growth in raw chip speed may
`begin to level off about 1994- but that
`other measures of performance, includ-
`ing power consumption and auxiliary
`functions, will still improve. The 100—
`gram flat-panel display, then, might be
`driven by a microprocessor that exe-
`cutes a billion operations per second
`and contains 16 megabytes of on-board
`memory along with sound, video and
`network interfaces. Such a processor
`would draw, on average, a few percent
`of the power required by the display.
`Auxiliary storage devices will aug-
`ment main memory capacity: conserva-
`tive extrapolation of current technol-
`ogy suggests that removable hard disks
`(or nonvolatile memory chips) the size
`of a matchbook will store about 60
`megabytes each. Larger disks contain-
`ing several gigabytes of information
`will be standard, and terabyte storagei
`roughly the data content of the Library
`of Congress—will be common. Such
`enormous stores will not necessarily
`be filled to capacity with usable infor-
`mation. Abundant space will, however,
`allow radically different strategies of
`information management. A terabyte
`of disk storage will make deleting old
`
`files virtually unnecessary, for example.
`Although processors and displays
`should be capable of offering ubiquie
`tous computing by the end of the dec-
`ade, trends in software and network
`technology are more problematic. Cur—
`rent implementations of “distributed
`computing" 'simply make networked
`file servers, printers or other devic-
`es appear as if they were connected
`directly to each user's computer. This
`approach, however, does nothing to ex—
`ploit the unique capabilities of physi-
`cally dispersed computers and the in-
`formation embodied in knowing where
`a particular device is located.
`
`omputer operating systems and
`windowebased display software
`will have to change substantial-
`ly. The design of current operating sys-
`tems, such as DOS and Unix, is based
`on the assumption that a computer’s
`hardware and software configuration
`will not change substantially while it is
`running. This assumption is reasonable
`for conventional mainframes and per-
`sonal computers, but it makes no sense
`in terms of ubiquitous computing.
`Pads, tabs and even boards may come
`and go at any time in any room, and
`it will certainly be impossible to shut
`down all the computers in a room to
`install new software in any one of
`them. (Indeed, it may be impossible to
`find all the computers in a room.)
`One solution may be “micro-ker-
`nel” operating systems such as those
`developed by Rick Rashid of Game
`gie Mellon University and A. S. Tanen—
`baum of Vrije University in Amster-
`dam. These experimental systems con-
`tain only the barest scaffolding of fixed
`computer code; software modules to
`perform specific functions can be read-
`ily added or removed. Future operat-
`ing systems based on this principle
`could shrink and grow automatically to
`fit the changing needs of ubiquitous
`computation.
`Current window display systems also
`are not ready to cope with ubiqui-
`tous computing. They typically assume
`that a particular computer will display
`all the information for a single appli-
`cation. Although the X Window Sys-
`tem and Windows 3.0, for example, can
`cope with multiple screens,
`they do
`not do well with applications that start
`out on one screen and move to anoth—
`er, much less those that peregrinate
`from computer to computer or room
`to room.
`
`Solutions to this problem are in their
`infancy. Certainly no existing display
`system can perform well while working
`with the full diversity of input and out-
`put forms required by embodied virtual-
`
`
`
`RADIO TRANSCEIVER links pads and
`other movable computer devices to the
`wired network. This unit, intended to
`be mounted on the ceiling, contains an-
`tennas in its crossed arms and two light-
`emitting diodes to signal its status.
`
`ity. Making pads, tabs and boards work
`together seamlessly will require chang—
`es in the kinds of protocols by which
`applications programs and their dis“
`played windows communicate.
`The network that will connect ubiq—
`uitous hardware and software poses
`further challenges. Data transmission
`rates for both wired and wireless net-
`works are increasing rapidly. Access to
`gigabit—per-second wired nets is already
`possible, although expensive, and will
`become progressively cheaper. (Giga-
`bit networks will seldom devote all
`of their bandwidth to a single data
`stream; instead they will allow enor-
`mous numbers of lower-speed trans-
`missions to proceed simultaneously.)
`Small wireless networks, based on dig—
`ital cellular telephone principles, cur
`rently offer data rates between two and
`10 megabits per second over a range
`of a few hundred meters. Lowwpow-
`er wireless networks capable of trans-
`mitting 250,000 hits per second to
`each station will eventually be available
`commercially.
`transparently
`Yet
`the problem of
`linking wired and wireless networks
`resists solution. Although some stop-
`gap methods have been developed, en-
`gineers must develop new communi—
`cations protocols that explicitly rec-
`ognize the concept of machines that
`move in physical space. Furthermore,
`the number of channels envisioned in
`most wireless network schemes is still
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`KEY COMPONENTS OF UBIQUITOUS COMPUTING are the pads and tabs under de-
`velopment at the Xerox Palo Alto Research Center. The pagevsize pad (top, exterior
`and interior views) contains two microprocessors, four million bytes of random-ac-
`cess memory, a high-speed radio link, a high-resolution pen interface and a black-
`and-white display that is 1,024 by 768 pixels. Because it uses standard window
`system software, the pad can communicate with most workstations. The much
`smaller tab (at left), 2 3/4 by 3 1/4 inches, has three control buttons, a pen interface,
`audio and an infrared link for communicating throughout a room. The author be-
`lieves future homes and offices will contain hundreds of these tiny computers.
`
`very small, and the range large (50
`to 100 meters), so that the total num-
`ber of mobile devices is severely lim-
`ited. The ability of such a system to
`support hundreds of machines in ev-
`ery room is out of the question. Sin-
`gle~room networks based on infrared
`or newer electromagnetic technologies
`have enough channel capacity for ubiq—
`uitous computers, but they can work
`only indoors.
`Present technologies would require a
`mobile device to have three different
`network connections: tiny-range wire—
`less, long-range wireless and very high
`speed wired. A single kind of network
`connection that can somehow serve all
`three functions has yet to he invented.
`
`P I either an explicationofthe prin-
`
`ciples of ubiquitous compute
`ing nor a list of the technolo-
`gies involved really gives a sense of
`what it would be like to live in a world
`full of invisible widgets. Extrapolating
`from today’s rudimentary fragments
`of embodied virtuality is like trying to
`predict the publication of Finnegans
`Woke shortly after having inscribed the
`first clay tablets. Nevertheless, the ef-
`fort is probably worthwhile:
`
`Sal awakens; she smells coffee. A few
`
`minutes ago her alarm clock, alerted
`by her restless rolling before waking,
`had quietly asked, “Coffee?” and she
`had mumbled, ”Yes.” “Yes” and “no”
`are the only words it knows.
`Sal looks out her windows at her
`neighborhood. Sunlight and a fence are
`visible through one, and through oth»
`ers she sees electronic trails that have
`been kept for her of neighbors coming
`and going during the early morning.
`Privacy conventions and practical data
`rates prevent displaying Video footage,
`but time markers and electronic tracks
`on the neighborhood map let Sal feel
`cozy in her street.
`Glancing at the Windows to her kids'
`rooms, she can see that they got up 15
`and 20 minutes ago and are already in
`the kitchen. Noticing that she is up,
`they start making more noise.
`At breakfast Sal reads the news. She
`still prefers the paper form, as do most
`people. She spots an interesting quote
`from a columnist in the business sec-
`tion. She wipes her pen over the news—
`paper’s name, date, section and page
`number and then circles the quote. The
`pen sends a message to the paper,
`which transmits the quote to her office.
`Electronic mail arrives from the come
`pany that made her garage door open-
`er. She had lost the instruction manu-
`al and asked them for help. They have
`sent her a new manual and also some—
`thing unexpected~a way to find the
`old one. According to the note, she can
`press a code into the opener and the
`
`missing manual Will find itself. In the
`garage, she tracks a beeping noise to
`where the oil-stained manual had fallen
`behind some boxes. Sure enough, there
`is the tiny tab the manufacturer had
`affixed in the cover to try to avoid E-
`mail requests like her own.
`On the way to work Sal glances in
`the foreview mirror to check the traf-
`fic. She spots a slowdown ahead and
`also notices on a side street the telltale
`green in the foreview of a food shop,
`and a new one at that. She decides to
`take the next exit and get a cup of cof-
`fee while avoiding the jam.
`Once Sal arrives at work, the fore-
`view helps her find a parking spot
`quickly. As she walks into the building,
`the machines in her office prepare to
`log her in but do not complete the se-
`quence until she actually enters her of-
`fice. On her way, she stops by the of-
`fices of four or five colleagues to ex
`change greetings and news.
`Sal glances out her windows: a gray
`day in Silicon Valley, 75 percent humidi-
`ty and 40 percent chance of afternoon
`showers; meanwhile it has been a quiet
`morning at the East Coast office. Usually
`the activity indicator shows at least one
`spontaneous, urgent meeting by now.
`She chooses not to shift the window on
`the home office back three hoursitoo
`much chance of being caught by sur-
`prise. But she knows others who do,
`usually people who never get a call from
`the East but just want to feel involved.
`The telltale by the door that Sal pro-
`
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`grammed her first day on the job is
`blinking: fresh coffee. She heads for
`the coffee machine.
`
`Coming back to her office, Sal picks
`up a tab and “waves” it to her friend
`Joe in the design group, with whom
`she has a joint assignment. They are
`sharing a virtual office for a few weeks.
`The sharing can take many forms—in
`this case, the two have given each other
`access to their location detectors and
`to each other’s screen contents and lo-
`cation. Sal chooses to keep miniature
`versions of all Joe’s tabs and pads in
`view and three-dimensionally correct in
`a little suite of tabs in the back corner
`of her desk. She can't see what any—
`thing says, but she feels more in touch
`with his work when noticing the dis-
`plays change out of the corner of her
`eye, and she can easily enlarge any-
`thing if necessary.
`A blank tab on Sal’s desk beeps and
`displays the word “Joe" on it. She picks
`it up and gestures with it toward her
`live board. Joe wants to discuss a docu»
`ment with her, and now it shows up on
`the wall as she hears Joe's voice:
`“I‘ve been wrestling with this third
`paragraph all morning, and it still has
`the wrong tone. Would you mind read-
`ing it? ”
`
`Sitting back and reading the para-
`graph, Sal wants to point to a word. She
`gestures again with the “joe” tab onto a
`nearby pad and then uses the stylus to
`circle the word she wants:
`“I think it’s this term ‘ubiquitous.’ It’s
`just not in common enough use and
`makes the whole passage sound a little
`formal. Can we rephrase the sentence
`to get rid of it?"
`
`“I'll try that. Say, by the way, Sal, did
`you ever hear from Mary Hausdorf ? “
`“No. Who's that?”
`“You remember. She was at the meet-
`ing last week. She told me she was go
`ing to get in touch with you."
`Sal doesn't remember Mary, but she
`does vaguely remember the meeting.
`She quickly starts a search for meet-
`ings held during the past two weeks
`with