The Computer for the 21st Century PDF

Mark Weiser Palo Alto Research Center, Xerox, CA, USA Specialized elements of hardware and software, connected by wires, radio waves and infrared, will be so ubiquitous that no one will notice their presence. The...

Mark Weiser Palo Alto Research Center, Xerox, CA, USA Specialized elements of hardware and software, connected by wires, radio waves and infrared, will be so ubiquitous that no one will notice their presence. The most profound technologies are those that disappear. them on new goals. 无缝的 集成的 They weave themselves 难以区分的 into the fabric of everyday life un- The idea of integrating computers seamlessly into the world 反对于 til they are indistinguishable from it. Consider writing, per- at large runs counter to a number of present-day trends. "Ubiq- haps the first information 象征性的 technology. The ability to represent uitous computing" in this context does丛林not mean just comput- 解放 机场 海边 spoken language symbolically for longterm storage freed in- ers that can be carried to the beach, jungle or airport. Even formation from 无处不在的the limits of individual memory. Today this the most powerful notebook computer, with access to a world- technology is ubiquitous in industrialized 转送 countries. Not only wide information 类比于 network, still focuses attention on a single do books, magazines and newspapers convey written informa- box. By analogy with writing, carrying a super-lap-top is like tion, 墙上涂鸦 but so do street signs, billboards, shop signs and even owning just one very important book. Customizing this book, graffiti. Candy wrappers are covered in writing. The constant even writing millions of other books, does not begin to capture background presence of these products of "literacy technol- the real power of literacy. ogy" 传送does not require active attention, but the information to Furthermore, although ubiquitous computers may use sound be transmitted is ready for use at a glance. It is difficult to and video in addition to text and graphics, that does not make imagine modern life otherwise. them "multimedia computers." Today's multimedia machine 硅基 Silicon-based inlbrmation technology, in contrast, is far makes the computer screen into a demanding focus of attention from having become part of the environment. More than 50 rather than allowing it to fade into the background. 直接地 million personal computers have been sold, and the computer Perhaps most diametrically opposed to our vision is the no- nonetheless 可亲近的 remains largely in a world 术语 of its own. It is ap- tion of virtual reality, 带上which attempts to make a world inside 护目镜 proachable only through complex jargon that has nothing to the computer. Users don special goggles that project an artifi- do with the tasks for 相似的 which people use computers. The state cial scene onto their eyes; they wear gloves or even bodysuits 书记 手势 of the art is perhaps analogous to the period when scribes had 制作纸的白泥 that sense their motions and gestures so that they can move to know as much about making 光环 ink or baking clay as they did about and manipulate virtual objects. Although it may have its 晦涩难解的 领域 about writing. The arcane aura that surrounds personal com- purpose in allowing people to explore realms otherwise inac- 不可及的 遥远的 puters is not just a "user interface" problem. My colleagues cessible - - the insides of cells, the surfaces of distant planets, and I at the Xerox Palo Alto Research Center think that the the information web of data bases - - virtual reality is only a 领土/版图 idea of a "personal" computerlaptop itself is misplaced and that the map, not a territory. It excludes desks, offices, other people not vision of laptop machines, 过度期的 dynabooks and "knowledge nav- wearing goggles and bodysuits, weather, trees, walks, chance igators" is only a transitional step toward achieving the real encounters and, in general, the infinite richness of the universe. 巨大的 装置 potential of information technology. 必需的 Such machines cannot Virtual reality focuses an enormous apparatus on simulating truly make computing an integral, invisible part of people's the world rather than on invisibly enhancing the world that al- lives. We are therefore trying to conceive a new way of think- ready exists. 概念/打算 ing about computers, one that takes into account the human Indeed, the opposition between the notion of virtual reality world and allows the computers themselves to vanish 消失 into the and ubiquitous, invisible computing is so strong that some of background. us use the term "embodied virtuality" to refer to the process Such a disappearance is a fundamental consequence not of of drawing computers out of their electronic shells. The "vir- 心理 technology but of human psychology. 缓和/减轻 Whenever people learn tuality" of computer-readable data - - all the different ways 足够 something sufficiently well, they cease to be aware of it. When in which they can be altered, processed and analyzed - - is you look at a street sign, for example, you absorb its infor- brought into the physical world. 有意识地 mation without conseiously performing the act of reading. How do technologies马达disappear into the background? The 有益的 Computer scientist, economist and Nobelist Herbert A. Si- vanishing of electric motors may serve as an instructive ex- 典型的 mon calls this phenomenon 不言自喻的 "compiling"; philosopher Michael ample. At the turn of the century, a typical workshop or fac- Polanyi calls it the 不变量 "tacit dimension"; psychologist J. J. Gibson tory contained a single engine that drove dozens or hundreds 轴 滑轮 calls it "visual invariants"; philosophers地平线/眼界 ttans Georg Gadamer of different machines through a system of shafts and pulleys. and Martin Heidegger call it the "horizon" and 边缘 the "ready-to- Cheap, small, efficient electric motors made it possible first to 动力 hand"; 本质上来说 John Seely Brown of PARe calls it the "periphery." All give each tool its own source of motive force, then to put many say, in essence, that only when things disappear in this way are motors into a single machine. 汽车 we freed 释放的/解放 to use them without thinking and so to focus beyond A glance through the shop manual of a typical automobile, 显示 螺线管 for example, reveals 22 motors and 25 solenoids. They start *Reprinted with permission. Copyright(c) 1991 by Scientific American, 挡风玻璃 Inc. All rightsreserved. This article firstappearedin ScientificAmerican,Vol. the engine, clean the windshield, lock and unlock the doors, 265, No. 3 (September199l), pp. 94-104 and so on. By paying careful attention, the driver might be Mobile Computing and Communications Review, Volume 3, Number 3 Figure 1: UBIQUITOUS C O M P U T I N G 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. Build- ing boards and integrating them with other tools has helped researchers understand better the eventual shape of ubiquitous computing. In conjunction with active badges, live boards can customize the information they display. Mobile Computing and Communications Review, Volume 3, Number 3  认识 able to discern whe~ever tie or she activated a motor, but there would be no point to it. Most computers that participate in embodied virtuality will 隐喻 be invisible in fact as welt 温控器 as in metaphor. Already comput- 立体声系统 ers in light switches, thermostats, stereos and ovens help to activate the world. 无处不在的 These machines and more will be inter- connected in a ubiquitous network. As computer scientists, however, 传播 my colleagues and I have focused on devices that transmit and display information more directly. We have found 重要的;决断性的 比例 two issues of crucial importance: 观念;看法 location and scale. 并置;并列 Little is more basic to human perception than physical juxtaposition, and so ubiquitous computers m u s t know where they are. (To- day's computers, in contrast, have no 仅仅 idea of their location and surroundings.) 调整 tf a computer knows merely what room it is in, it can adapt its behavior 人工智能 in significant ways without requiring even a hint of artificial intelligence. Ubiquitous computers will also come in diffcrent sizes, each suited to a particular task. My colleagues and I have built what we call tabs, pads and boards: inch-scale machines that 便利贴 approximate active Post-it notes, foot-scale ones that behave something like a sheet of paper (or a book or a magazine) and yard-scale 公布/公告 displays that are the equivalent of a blackboard or bulletin board. How many tabs, pads and board-size writing and display surfaces are there in a typical room? Look around you: at 脊梁 the inch scale, include wall notes, titles on book spines, labels on controls, 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 deploying the hardware of embodied Figure 3: The Active Badge - This harbinger of inch-scale virtuality: hundreds of computers per room. 恐怖 computers contains a small microprocessor and an infrared Hundreds of computers in a room could seem intimidating transmitter. The badge broadcasts the identity of its wearer and 伏特 追赶/过程 at first, just as hundreds of volts coursing through wires in the so can trigger automatic doors, automatic telephone forward- walls once did. But like the wires in the walls, these hundreds ing and computer displays customized to each person reading of computers will come to be invisible to common 实现 awareness. them. The active badge and other networked tiny computers People will simply use them unconsciously to accomplish ev- are called tabs. eryday tasks. Tabs are the smallest components of embodied virtuality. 实用性 Because they are interconnected, tabs will expand on the use- No revolution in artificial intelligence is needed, merely com- fulness of existing inch-scale computers, such as the pocket puters embedded in the everyday world. 包含 记事本 calculator and the pocket organizer. Tabs will also take on My colleague Roy Want has designed a tab incorporating a functions that no computer performs today. For example, small display that can serve simultaneously as an active badge, computer scientists at PARC and other research laboratories 徽章 calendar and diary. It will 收缩also act as an extension to com- around the world have be gun working with active badges puter screens: instead of shrinking a program window down 夹性 - -clip-on computers roughly the size of an employee I.D. to a small icon on the screen, for example, a user will be able card, first developed by the Olivetti Cambridge research lab- to shrink the window onto a tab display. This will leave the oratory. These badges can identify themselves to receivers screen free for information and also let people arrange their placed throughout a building, thus making it possible to keep computer-based projects in the area around their terminals, 堆 track of the people or objects to which they are attached. much as they now arrange paper-based projects in piles on In our experimental embodied virtuality, doors open only to desks and tables. Carrying a project to a different office for 接待 the right badge wearer, rooms greet people by name, telephone discussion is as simple as gathering up its tabs; the associated calls can be接待员automatically forwarded to wherever the recipient programs and files can be called up on any terminal. may be, receptionists actually know where people are, com- The next step up in size is the pad, something 掌上型 of a cross puter terminals retrieve the preferences of whoever is sitting between a sheet of paper and current laptop and palmtop com- 记事本 at them, and appointment diaries write themselves. The auto- puters. Robert Krivacic of PARC has built a prototype pad matic diary shows how such a simple 红利 task as knowing where that 多按钮 uses two铁针microprocessors, a workstation-size display, a 变成 people are can yield complex dividends: meetings, for exam- multibutton 带宽 stylus and a radio network with enough communi- ple, consist of several people spending time in the same room, cations bandwidth to support hundreds of devices per person and the subject of a meeting is most probably the files called per room. 习惯的 便于携带的 up on that room's display screen while the people are there. Pads differ from conventional portable computers in one Mobile Computing and Communications Review, Volume 3, Number Figure 2: W I R E D AND W I R E L E S S N E T W O R K S link computers and allow their users to share programs and data. The computers pictured here include conventional terminals and file servers, pocket-size machines known as tabs and page-size ones known as pads. Future networks must be capable of supporting hundreds of devices in a single room and must also cope with devices ranging from tabs to laser printers or large-screen displays - - that move from one place to another. crucial way. Whereas portable computers go everywhere with remains one of the many attractions of paper. Similar objec- their owners, the pad that must be carried废旧电脑 from place to place 类似于 tions apply to using a board as a desktop; people will have to 习惯于 is a failure. 废纸Pads are intended to be "scrap computers" (anal- become accustomed to having pads and tabs on a desk as an 附属 ogous to scrap paper) that can be grabbed and used anywhere; adjunct to computer screens before taking embodied virtuality they have no individualized identity or importance. 对抗手段 any further. One way to think of pads is as an antidote to windows. Win- Prototype boards, built by Richard Bruce and Scott Elrod dows were invented at PARC and popularized by Apple in the of PARC, are in use at several Xerox research laboratories. Macintosh as a way of fitting several different activities onto They measure about 40 by 60 inches and display 1,024 by 768 the small space of a computer screen at the same time. In black-and-white pixels. To manipulate the display, users pick 粉笔 20 years computer screens have not grown much larger. Com- up a piece of wireless electronic "chalk" that can work either in puter 隐喻 window systems are often said to be based on the desktop contact with the surface or from a distance.豚鼠(实验对象这里) Some researchers, metaphor - - but who would ever use a desk only nine inches using themselves调解and their colleagues as guinea pigs, can hold high by 11 inches wide? electronically mediated meetings or engage in other forms of 铺开 Pads, in contrast, use a real desk. Spread many electronic collaboration around a live board. Others use the boards as pads around on the desk, just as you spread out papers. Have testbeds for improved display hardware, new "chalk" and in- many tasks in front of you, and use the pads as reminders. Go teractive software. 微妙的 beyond the desk to drawers, shelves, coffee tables. Spread the For both obvious and subtle reasons, the software that ani- many parts of the many tasks of the day out in front of you mates a large shared display and its electronic chalk is not the to fit both the task and the reach of your arms and eyes rather same as that for a workstation. Switching back and forth be- than to fit the limitations of glassblowing. Someday pads may tween chalk and keyboard 质量上 may involve walking several steps, even be as small and light as actual paper, but meanwhile they and so the act is qualitatively different from using a keyboard 满足 can fulfill many more of paper's functions than can computer and mouse. In addition, body size is an issue. Not everyone screens. can reach the top of the board, so a Macintosh-style menu bar Yard-size displays (boards) serve a number of purposes: in might have to run across the bottom of the screen instead. 允许 the home, video screens and bulletin boards; in the office, bul- 翻页式展示图 We have built enough live boards to permit casual use: they 普通的 letin boards, white boards书柜 or flip charts. A board might also have been placed in ordinary conference rooms and open ar- serve as an electronic bookcase from which one might down- eas, and no one need sign up or give advance notice before load texts to a pad or tab. For the time being, however, the 膝盖 using them. By building and using these boards, researchers ability to pull out a book and place it comfortably on one's lap start to experience and so understand a world in which corn- Mobile Computing and Communications Review, Volume 3, Number 3  purer interaction in%finally enhances every room. Live boards can usefully be shared 使发生 across rooms as well as within them. In experiments instigated by Paul Dourish of EuroPARC 分开的 and Sara Bly and Frank Halasz of PARC, groups at widely sepa- rated sites gathered 共同地 around boards - - each displaying the same image - - and jointly composed pictures and 大西洋 drawings. They have even shared two boards across the Atlantic. Live boards can also be used as bulletin boards. 领会 There is already too much text for people to read and comprehend all of it, and so Marvin Theimer and David Nichols of PARC have 使协调; 使合拍 built a prototype system that attunes its public 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 computing. The real power of the concept comes 出现 not from any one of these devices - - it emerges from the inter- action of all of them. The hundreds of processors and displays are not a "user interface" like a mouse and windows, just a pleasant and effective "place" to get things done. What will be most pleasant and effective is that tabs can 迟钝的,无自动力的 animate objects previously inert. They can beep to help lo- Figure 5: R A D I O T R A N S C E I V E R links pads and other 遗失的 cate mislaid papers, books or other items. File drawers can movable computer devices to the wired network. This unit, open and show the desired folder - - no searching. Tabs in li- intended to be mounted on the ceiling, contains antennas in its brary catalogues can make active maps to any book and guide crossed arms and two light-emitting diodes to signal its status. searchers to it, even if it is off the shelf, left on a table by the last reader. 头顶上 In presentations, the size of text on overhead slides, 周围的 the vol- 放大的 ume of the amplified voice, even the amount of ambient light, structions per second in 1986 and continue to double each year. can be determined not by guesswork but by the desires of the Some industry observers believe that 趋平 this exponential growth 计算 listeners in the room at that moment. Software tools for tally- in raw chip speed may begin to level off about 1994 but that ing votes instantly and consensus checking are already avail- other measures 辅助的 of performance, including power consump- able in electronic meeting rooms of some large corporations; tion and auxiliary functions, will still improve. The 100-gram 嵌板 tabs can make them widespread. flat-panel display, then, might be driven by a microprocessor The technology required for ubiquitous computing comes in that executes a billion operations per second and contains 16 three parts: cheap, low-power computers that include equally megabytes of on-board memory along with sound, video and 消耗 convenient displays, software for ubiquitous applications and network interfaces. Such a processor would draw, on average, a few percent of the power required by the display. a network that ties them all together. Current trends suggest 增加 that the first of these requirements will easily be met. Flat- Auxiliary storage devices will augment main memory ca- 保守的 推断 panel displays containing 640 x 480 black-and-white pixels pacity: conservative extrapolation of current technology sug- 不挥发的 are now common. This is the standard size for PCs and is gests that removable 纸板火柴 hard disks (or nonvolatile memory chips) also about right for television. As long as laptop, palmtop and the size of a matchbook will store about 60 megabytes each. notebook computers continue to grow in popularity, display Larger disks containing several gigabytes of information will prices wilt fall, and resolution and quality will rise. By the be standard, and terabyte storage - - roughly the data content end of the decade, a 1,000 x 800-pixel high-contrast display of the Library of Congress - - will be common. Such enor- will be a fraction of a centimeter thick and weigh perhaps 100 mous stores will not 充足的 necessarily be filled to capacity with us- 彻底地 grams. A small battery will provide several days of continuous able information. Abundant space will, however, allow radi- use. cally different strategies of information management. 事实上 A ter- Larger displays are a somewhat different issue. If an inter- abyte of disk storage will make deleting old files virtually un- active computer screen is to match a white board in usefulness, necessary, for example. it must be viewable from arm's length as well as from across Although processors and displays should be capable of of- 密度 a room. For close viewing, the density of picture elements fering ubiquitous computing by the end of the有问题的decade, trends in should be no worse than on a standard computer screen, about software and network technology 分散的 are more problematic. Cur- 80 per inch. Maintaining a density of 80 pixels per inch over rent implementations of "distributed computing" simply看起来 make 像是 an area several feet on a side implies displaying tens of mil- networked file servers, printers or other devices appear as if lions of pixels. The biggest computer screen made today has they were connected directly to each user's computer. This only about one fourth that capacity. Such large displays will approach, however, does nothing to exploit the unique capa- 散步的 probably be expensive, but they should certainly be available. bilities 体现 of physically dispersed computers and the information The large display will require advanced microprocessors to embodied in knowing where a particular device is located. feed it. Central-processing-unit speeds reached a million in- Computer operating systems and window-based display Mobile Computing and Communications Review, Volume 3, Number 3 Figure 4: C O M P U T E R SCRATCHPADS augment the conventional screen in this office at the Xerox Palo Alto Research Center. Prototype pads are wired to conventional computers; thus far only a handful of wireless models have been built. 实质上 旅行 software will have to change substantially. The design of cur- to another, much less those that peregrinate from computer to rent operating systems, such as DOS and Unix, is based on computer or room to room. 幼年期 the assumption that a computer's hardware and software con- Solutions to this problem are in their infancy. Certainly figuration will not change substantially 老一套的 while it is主机 running. no existing display system can perform well while working This assumption is reasonable for conventional mainframes with the full diversity of input and output forms required by and personal computers, but it makes no sense in terms of embodied virtuality. Making pads, tabs and boards work to- 无缝地 协议 ubiquitous computing. Pads, tabs and even boards may come gether seamlessly will require changes in the kinds of proto- and go at any time in any room, and it will certainly be impos- cols by which applications programs and their displayed win- sible to shut down all the computers in a room to install new dows communicate. software in any one of them. (Indeed, it may be impossible to find all the computers in a room.) The引起 network that will connect ubiquitous hardware and soft- 核心;内核 ware poses further challenges. Data transmission rates for both One solution may be "micro-kernel" operating systems such wired and wireless networks are increasing rapidly. Access as those developed by Rick Rashid of Carnegie Mellon Univer- to gigabit-per-second wired nets is already possible, although sity and A. S. Tanenbaum of Vrije University 裸露的(before in Amsterdam. 最基本的) 框架 expensive, and will become progressively cheaper. (Gigabit 很少 把...奉献 These experimental systems contain only the barest scaffold- networks will seldom devote all of their bandwidth to a sin- ing of fixed computer code; software modules to perform spe- gle data stream ; instead they will allow enormous numbers of cific functions can be readily added or removed. Future op- lower-speed transmissions to proceed simultaneously.) Small 细胞的;多孔的;移动电话 erating systems based on this principle could shrink and grow wireless networks, based on digital cellular telephone princi- automatically to fit the changing needs of ubiquitous compu- ples, currently offer data rates between two and 10 megabits tation. per second over a range of a few hundred meters. Low-power 处理 Current window display systems also are not ready to cope wireless networks capable of transmitting 250,000 bits per sec- with ubiquitous computing. They typically assume that a par- ond to each station will eventually be available commercially. 商业上的 明亮地;显然地 ticular computer will display all the information for a single Yet the problem of transparently linking wired and wireless 抵制 application. Although the X Window System and Windows networks resists solution. Although some stop-gap methods 3.0, for example, can cope with multiple screens, they do not have been developed, engineers must develop new communi- do well with applications that start out on one screen and move cations protocols that explicitly recognize the concept of ma- 8 Mobile Computing and Communications Review, Volume 3, Number 3 chines that move 展现 in physical space. Furthermore, the number greetings and news. of channels envisioned in most wireless network schemes is Sal glances out her windows: a gray day in Silicon Val- 湿度 still very small, and the range large (50 to 100 meters), so ley,洗澡(这里是降雨) 75 percent humidity and 40 percent chance of afternoon that the total number of mobile devices is severely limited. showers; meanwhile it has been a quiet morning at the East The ability of such a system to support hundreds of machines Coast office. Usually the activity indicator shows at least 推one 自发的, 无意识的 in every room 红外线 is out of the question. 电磁的 Single-room networks spontaneous, urgent meeting by now. She chooses not to shift based on infrared or newer electromagnetic technologies have the window on the home office back three hours - - too much enough channel capacity for ubiquitous computers, but they chance of being caught by surprise. But she knows others who can work only indoors. do, usually people who never get a call from the East but just Present technologies would require a mobile device to have want to feel指示灯 involved. three different network connections: tiny-range wireless, long- The telltale by the door that Sal programmed her first day range wireless and very high speed wired. A single kind of on the job is blinking: fresh coffee. She heads for the coffee network connection that can somehow serve all three functions machine. Coming back to her office, Sal picks up a tab and has yet to be invented. "waves" it to 共同的 her friend Joe in the design group, with whom 说明 Neither an explication of the principles of ubiquitous com- she has a joint assignment. They are sharing a virtual office puting nor a list of the technologies involved really gives a for a few weeks. The sharing can take many forms - - in this sense of what it would be like to live in初步a world full片段of invisible case, the two have given each other access to their location 小工具 推断 探测仪 widgets. Extrapolating from today's rudimentary fragments of detectors and to each other's screen contents and location. Sal 预知 embodied virtuality is like trying to predict the publication of chooses to keep miniature versions of all Joe's tabs and pads 题写 维度 Finnegans Wake shortly after having inscribed the first clay in view and three-dimensionally correct in a little suite of tabs 有价值的 tablets. Nevertheless, the effort is probably worthwhile: in the back corner of her desk. She can't see what anything Sal awakens; she smells 焦躁不安的 coffee. A few minutes ago her says, but she feels more in touch with his work when noticing alarm clock, alerted by her restless rolling before waking, had the displays change out of the corner of her eye, and she can 放大 quietly asked, "Coffee ?" and she had mumbled, "Yes." "Yes" easily enlarge anything if necessary. and "no" are the only words it knows. Sal looks out her win- A blank tab on Sal's desk 指向 beeps and displays the word "Joe" 栅栏 dows at her neighborhood. Sunlight and a fence are visible on it. She picks it up and gestures with it toward her live board. through one, and through others she sees electronic trails that Joe wants to discuss a document with her, and now it shows up have been kept for her of neighbors coming and going during on the wall as she hears Joe's voice: 摔跤(这里指思考) 习俗;协议 the early morning. Privacy conventions and practical data rates "I've been wrestling with this third paragraph all morning, 连续镜头;英尺长度;片段 prevent displaying video footage, but time markers and elec- and it still has the wrong tone. Would you mind reading it?" 舒适的 tronic tracks on the neighborhood map let Sal feel cozy in her Sitting back and reading the paragraph, Sal wants to point street. to a word. She gestures again with the "Joe" tab onto a nearby Glancing at the windows to her kids' rooms, she can see pad and then uses the stylus to circle the word she wants: that they got up 15 and 20 minutes ago and are already in the "I think it's this term 'ubiquitous.' It's just not in common kitchen. Noticing that she is up, they start making more noise. enough use and makes the whole passage sound a little formal. At breakfast Sal reads the news. She still prefers the paper Can we rephrase the sentence to get rid of it?" form, as do most people. She spots an interesting 擦去 quote from a "I'll try that. Say, by the way, Sal, did you ever hear from 专栏作家 columnist in tile business section. She wipes her pen over the Mary Hausdorf?" newspaper's name, date, section and page number and then "No. Who's that?" circles the quote. The pen sends a message to the paper, which "You remember. She was at the meeting last week. She told transmits the quote to her office. me she was going to get in touch with you." 含糊的 车库 Electronic mail arrives from the company that made her Sal doesn't remember Mary, but she does vaguely remem- garage door opener. She had lost the instruction manual and ber the meeting. She quickly starts a search for meetings held asked them for help. They have sent her a new manual and also during the past two weeks with more than six people not pre- something unexpected - - a way to find the old one. According viously in meetings with her and finds the one. The attendees' to the note, she can press a code into the opener and the miss- names pop up, and she sees Mary. 生平的 ing manual will find itself. In the garage, she tracks a beeping As is common in meetings, Mary made some biographical 沾满油污的 noise to where the oil-stained manual had fallen behind some information about herself available to the other attendees, and boxes. 粘贴;署名 Sure enough, there is the tiny tab the manufacturer had Sal sees some common background. She'll just send Mary a affixed in the cover to try to avoid Email requests like her own. note and see what's up. Sal is glad Mary did not make the 展望 传记 On the way to work Sal glances in the foreview mirror to biography available only during the time of the meeting, as check the traffic. She spots a slowdown ahead and also notices many people do.... 说明问题的;泄露信息的 on a side street the telltale green in the foreview of a food shop, In addition to showing some of the ways that computers can and a new one at that. She decides to take the next exit and get enter invisibly into people's lives, this scenario points up some 具体表现;包含;体现 造成;引起 拥挤 a cup of coffee while avoiding the jam. of the social issues that embodied virtuality will engender. Per- 前部的 Once Sal arrives at work, the fore view helps her find a haps key among them is privacy: hundreds of computers in ev- parking spot quickly. As she walks into the building, the ma- ery room, all capable of sensing people near them and极权主义 linked chines in her office prepare to log her in but do not complete by high-speed networks, have 完全 the potential 无政府状态 to make totalitari- the sequence until she actually enters her office. On her way, anism up to now seem like sheerest anarchy. Just as a worksta- she stops by the offices of four or five colleagues to exchange tion on a local-area network can be programmed to intercept Mobile Computing and Communications Review, Volume 3, Number 3 9  \ Figure 6: KEY C O M P O N E N T S OF U B I Q U I T O U S C O M P U T I N G are the pads and tabs under development at the Xerox Palo Alto Research Center. The page-size pad (top, exterior and interior views) contains two microprocessors, four million bytes of random-access 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 (bottom), 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 believes future homes and offices will contain hundreds of these tiny computers. 游手好闲的 定居 messages meant for others, a single rogue tab in a room could computers, in contrast, reside in the human world and pose 透明的 potentially record everything that happened there. no barrier to personal interactions. If any thing, the transpar- Even today the active badges and selfwriting appointment ent connections that they offer between different locations and diaries that offer all kinds of convenience could be a source of times may tend to bring communities closer together. 公司 上层 real harm in the wrong hands. Not only corporate superiors My colleagues and I at PARC believe that what we call ubiq- 下属 过分热心的 显出 or underlings but also overzealous government officials and uitous computing will gradually emerge as the dominant mode even marketing firms could make unpleasant use of the same of computer access over the next 20 years. Like the personal information that makes invisible computers so convenient. computer, ubiquitous computing will produce nothing funda- 关于暗号的 Fortunately, cryptographic techniques already exist to se- mentally new, 张力;负担 but by making everything faster and easier 体操;体育 改变 to cure messages from one ubiquitous computer to another and do, with less strain and fewer mental gymnastics, it will trans- to safeguard private information stored开始;开端 in networked systems. form what is ap patently possible. Desktop publishing, for ex- 排字;排版 故意;有计划 If designed into systems from the outset, these techniques ample, is定日期 essentially no different from computer typesetting, can ensure that private data do not become public. A well- which dates back to the mid-1960s. But ease of use makes an implemented version of ubiquitous computing could even at- enormous difference. ford better privacy protection than exists today. When almost every object either contains a computer or can 琐碎的 By pushing computers into the background, embodied vir- have a tab attached to it, obtaining information will be trivial: tuality will make individuals more aware of the people on the "Who made that dress? Are there any more in the store? What other ends of their computer links. This development may re- was the name of the designer of that suit I liked last week? " 向心的 verse the unhealthy centripetal forces that conventional per- The computing environment knows the suit you looked at for 引见;介入 sonal computers have introduced into life and the workplace. a long time last week because it knows both of your locations, 躲藏 追溯地 Even today, people holed up in windowless offices before and it can retroactively find the designer's name even though 感兴趣 glowing computer screens may not see their fellows for the that information 社会学上地 did not in terest you at the time. better part of each day. And in virtual reality, the outside world Sociologically, ubiquitous computing may mean the decline and all its inhabitants eft~ctively cease to exist. Ubiquitous of the computer addict. In the 1910s and 1920s many people 有瘾的人;使上瘾; 居民 停止;终止 成瘾者  adj.恼火的 v.劈砍. 这里代表破解 矿石收音机 "hacked" on crystal sets to take advantage of the new high-tech world of radio. Now crystal-and-cat's-whisker receivers are rare because high-quality radios are ubiquitous. In总裁;主席addition, embodied virtuality will bring computers to the presidents of industries and countries for nearly the first time. Computer 穿过 access will penetrate all groups in society. Most important, ubiquitous使超载;使过载 computers will help overcome the problem of information overload. There is more informa- tion available at our fingertips during a walk in the woods than in any computer system, yet people find a walk among trees 令人沮丧的 relaxing and computers frustrating. Machines that fit the hu- man environment instead of forcing humans to enter theirs will make using a computer as refreshing as taking a walk in the 耳目一新 woods. FurCher Reading The Tacit Dimension, Michael Polanyi, Doubleday and Company, 1966. "Toward Portable Ideas," Mark Stefik and John Seely Brown, Technological Support.for Work Group Collab- oration, Edited by Margrethe H. Olson, Lawrence Erl- baum Associates, 1989. "Recent Developments in Operating Systems," Special issue oflEEE Computer, Vol. 23, No. 5, May 1990. "Activity-Based Information Retrieval: Technology in Support of Humanmemory," Mik Lamming and William Newman, Available as Rank Xerox EuroPARC Technical Report 91-03, February 1991. "LCDs and Beyond," Nick Baran, Byte, Vol. t 6, No. 2, pages 229-236, February 1991. "A Talk with Intel," Kenneth M. Sheldon, Byte, Vol. 16, No. 4, pages 131 140, April 1991. Mobile Computing and Communications Review, Volume 3, Number 3 11