From Pbooks to Ebooks


Larry Press

Communications of the ACM, May 2000, Volume 43 Issue 5.



The dream of electronic books (Ebooks) has been with us at least since Vannevar Bush published his famous article As We May Think, in which he speculated on a desk-sized machine which would hold ones personal writing and library [1].  Alan Kay named his prototype of the modern personal computer the Dynabook, and related research has been done at prestigious centers including Xerox PARC, MIT, Bell Labs, and Brown University.  I have speculated about Ebooks and portable devices earlier, e. g. [6, 7], but am still reading paper books (Pbooks) because content is abundant and user interaction is simple and subconscious.  The idea of an Ebook is appealing – a single device with an entire library of interlinked documents, dictionary lookup, unlimited, sharable annotation, search capability, and so forth, but the technology to date has not been good enough to displace the Pbook.  Is it now?


For a first pass at answering that question, I looked at two new Ebook devices, the Rocket Ebook (REB) from NuvoMedia,, and the Softbook (SB) from Softbook Press,  These are PC pads with flash RAM storage and backlit, touch-sensitive monochrome screens.  The REB is 5x7.5 inches and weighs 22 ounces and the SB is 8.75 x 8.5 inches and weighs 2.9 pounds.  Both are designed solely for reading and annotating documents, and they have simple user interfaces.  The REB has three buttons:  on/off, page forward and page backward, and the SB four buttons:  a neat rocker switch for next/previous page plus menu, top-of-document, and device-contents buttons. 


If I were an early gadget adopter or traveled a lot, I would get one of these devices.  I prefer them to a standard laptop PC for reading.  They balance well, have reasonable battery life, are small and light, turn pages fairly thoughtlessly, boot quickly and never display Windows’ “blue screen of death.”  However, I am not ready to purchase one today because new technology and business models are being developed, and which will lead to improved devices and the availability of more content.  Let’s examine some of the technology and the business considerations.




CPU speed is steadily improving, and more horsepower will be helpful.  Boot time for both the REB and SB is under 5 seconds, but the time to open a document by loading it from storage to RAM is noticeable.  The REB is slowest, taking about 25 seconds to load the Random House Dictionary.  More subtle, but more important, is the time it takes to “turn” a page.  The REB takes what seems to be about a second, and the SB is faster, but the time to paint a new page is still noticeable.  If one is to become lost or absorbed in reading, the device must become transparent, disappearing from consciousness.  Page-turn times should be imperceptible, and the page-turn gesture thoughtless.  Ebooks have an advantage over Pbooks here -- the page toggle bar on the SB is superior to the buttons on the REB, and both beat a Pbook.


CPU power consumption has also improved steadily during the last decade with new chip processes, shrinking feature sizes, and lower voltage levels.  Operating systems have also become more efficient, slowing or stopping processors to save power when full speed was not needed.  Transmeta,, may realize further power savings with their newly announced x86-compatible CPUs targeted for handheld and notebook devices.  Transmeta’s voltage and clock rates can be changed on the fly, and their benchmarks show substantial power saving over x86 processors at comparable application speeds.  Of course systems use power for displays, storage and other components as well as the CPU.  The REB claims 20-40 hours between charges, depending upon settings and usage, and the SB claims 5 hours.  These are respectable figures using today’s technology, and we can look forward to improvement.


Storage is another key element.  The speed, capacity and cost of flash storage have improved steadily over time, and it has been used in many portable devices, including today’s Ebooks which come with between 2-32 MB.  To calibrate that, I loaded 5 newspapers and magazines and four books totaling 1,238 pages in an 8 MB SB.  This is sufficient for reading on a plane or a weekend vacation, but it is not the lifetime library Vannevar Bush dreamt of.  The capacity of rotating devices like IBM’s 340 MB, 1-inch micro disk,, is greater today, but in the long run, electronic storage would seem more robust and power efficient.  Matchbook-size compact flash capacities are around 200 MB, flash PC-cards hold 1.2 GB, and price falls by around 50% and capacity doubles every year or so.


Screen technology has not improved as quickly as electronics or storage.  We have not seen “Moore’s Law” improvements in pixel density, contrast, power consumption, and so forth, but costs are falling.  The reading area on the REB screen is about 3 x 4.5 inches and the SB 5.9 x 7.5.[1]  If after 500 years we have not converged on a standard page size for Pbooks, there probably is no optimal screen size for Ebooks; however, subjectively, the REB is too small for extended general reading.  On the other hand, it is fine for more limited reading, and the small screen saves power, allows a slower processor than the SB, and results in a smaller, lighter device.  In the long run, new technology may eliminate such tradeoffs.  For example, the LCD display may give way to products based on electronic paper,, from Xerox or electronic ink,, spun off from the MIT Media Lab [8].  These hope to deliver high contrast, low power, thin, light, rugged, displays that can be read without backlighting and in daylight, but it is too soon to say whether they will succeed. 


New software will also improve the legibility of today’s LCD displays.  Microsoft ClearType,,  essentially increases screen resolution by addressing the red, green and blue sub-pixels of an LCD display, producing dramatically sharper text than full-pixel anti-aliasing.[2]  Microsoft has many years experience in screen readability, having commissioned the Georgia and Verdana fonts expressly for the screen and having developed TrueType outlines and hints.  ClearType researcher Bill Hill believes we subconsciously recognize word shapes when reading Pbooks.  The technology to facilitate this has been developed over hundreds of years of subtle changes in typography and page design, and it involves roughly 20 factors like kerning, leading, and serifs.  The higher resolution of a ClearType display makes these possible on today’s LCD screens.  ClearType is now available in some pocket-sized machines, and they will soon ship Reader, a ClearType-based program for reading on notebook computers.  Microsoft is committed to including ClearType in Windows 2000 when product release cycles permit, though it will become less critical as LCD densities increase.  (LCD densities are expected to double in the next year or two).


Network connectivity is also integral to Ebooks, and both the REB and SB download their content.  The SB has a built-in modem, and a single click dials a server where one orders and downloads books and periodicals.  An Ethernet interface is also available.  The REB comes with a cradle that plugs into the serial port of a PC which is used to download content from a Web site.  The SB scheme is simpler for the user, and, since the content is never on a PC, it is more secure for the publisher.  With future products, one might download reading (or listening or viewing) material to a PC, save it on PCcard or other media, and plug that into an Ebook.  Given sufficient bandwidth, we might download entire works to Ebooks or read them directly over a wireless network connection.  Third generation cellular standards at rates up to 2 Mb/s are now being defined, and, with the International Telecommunications Union and the European Community taking the lead, rollout is expected to be underway in 3 years.[3]  At 2 Mb/s, one could download books and articles on demand, clicking on any interesting reference when it occurs.  Wireless LAN standards are already at 11 mb/s.  If one’s home, business or school had a high-speed connection to the Internet and a wireless LAN, reading material could be retrieved on demand today.


Bundling and form factor options are also improving.  The REB and EB are single function devices, used only for reading.  But, could we not package more in the same or a slightly modified device?  If you check a student’s backpack, you might find a PDA, CD or MP3 music player, cell phone, books, note books, and so forth.  In a few years, these applications will all fit in a package the size of the SB with a microphone and speaker or a wireless headset for telephony, music, video, voice annotation, note taking, and control.[4]  A conventional laptop with a keyboard may also be adaptable to comfortable reading with clever mechanical design.  Since I consider reading a “killer app,” I would start with a device that was optimally designed for reading, and add only those functions which did not detract from that.


The first Pbooks were large Bibles, chained to tables in monasteries.  It took about 50 years to evolve the form factor of the portable Pbook and much longer to settle on typography, punctuation, and so forth.[5]  There are many possible application bundles for Ebooks, and the winner will evolve as a function of engineering and efficiency, consumer taste, standards, and business considerations. 


Business Considerations


The manufacturers of EB, REB and others are beginning to offer electronic versions of commercial Pbooks, and their business model seems to be “sell them the razor then sell them the blades.”  The devices cost $200 (REB) or $600 (SB), and electronic titles cost about the same as the print versions -- there is no major  savings from the elimination of printing, retail facilities, shipping, or inventory costs.  If there are truly savings in production and distribution, competition and market forces will ensure that some are passed on to consumers in the future.


While commercial books and periodicals are important, most of what we read is non commercial, and SB and REB have software that allows users to create their own documents.  I tried the program which quickly converted some ASCII and HTML documents to the .reb format.  While this is a step in the right direction, it is only a step.  Material prepared for one medium can seldom be automatically moved to another.  The small REB screen left HTML tables unreadable and, of course, links did not work.


The .reb format will not become a standard.  Today, nearly all electronic documents are personal writing or relatively specialized reports and business documents in word processing, HTML or the Adobe Portable Document Format (PDF)  Adobe plans to revise their Acrobat PDF reader for Ebooks.[6]  The new version will include CoolType, their own sub-pixel font rendering technology, the ability to re-flow text to fit varying screen sizes (while retaining the underlying page structure for printing), and encryption.  Adobe also has their Merchant server which works in conjunction with an enhanced version of Acrobat to provide secure payment for Ebooks, and they will support EBX,, a proposed rights management standard.


Microsoft will soon release Reader,, a reading program for laptop and PDA computers.  Reader will incorporate ClearType and support the Open Ebook format.  Open Ebook is a file and format standard based on HTML and XML.  It was defined by the Open Book Initiative,, of the National Institute of Standards and Technology (NIST) with the participation of many prominent companies, including Adobe and Microsoft.  Users will be able to create Open Ebook  documents using Microsoft Word,[7] and, like Acrobat, Reader will be freely downloadable.  The user interface will be designed for effortless page turning, riffling through pages, annotation, and so forth, and the promise of this software on millions of portables has led major publishers to commit to electronic versions of many Pbook titles.[8] 


We are in for an Adobe/Microsoft contest.  The proof of the pudding will be seeing and evaluating Reader and the new Acrobat side by side, but there will also be business considerations.  Adobe starts with a huge installed base, and Microsoft may be looking over their shoulders at the Government, but the financial muscle of Microsoft and the imprimatur of NIST are not to be taken lightly.[9]


We will also see new publishing models.  Authors are invited to self-publish at Fatbrain,  Document prices start at $2, and the author receives a 50% royalty.  Documents may be in a number of popular formats, there is no charge for posting them, and they may be edited by the author at any time (creating a version control problem for readers).  One finds both well known authors like Arthur C. Clark and unknowns at Fatbrain.  The emergence and acceptance of methods for micro-payments like Compaq’s Millicent,, will enable more twists on this business model because the overhead of a credit card transaction will be eliminated.


NetLibrary,, sells collections of Ebooks to libraries.  For example, the University of Texas has 6,000 books which students may browse through for 15 minutes while deciding whether or not to check them out.  The business model uses the physical library metaphor in that if an Ebook is checked out, it is unavailable to another library patron.  As with paper books, the library can purchase multiple copies of popular titles. 


Textbooks (which can cost $100 or more) and teaching materials would seem to be a ripe Ebook market.  There is also an excellent fit with efforts to develop devices to facilitate note taking and automate the capture of the dialog that takes place in a classroom.  For an example of this research, see the Classroom 2000 project at Georgia Tech,, with its “Zen Book” reader/note taker.


Of course, most publishing is non-commercial.  Ebooks will be used for the countless business and personal documents we and our organizations create daily, and there are also non-commercial public forums.  Project Gutenberg,, is the granddaddy of all digital book libraries.  It has been growing since 1971, and has nearly 3,000 books.  Universities also have important electronic publishing efforts, for example, Brown University,, and the University of Virginia,, have pioneered in Ebook and library technology and in collection building. 


Scholarly publication has been on weak financial grounds for years since journals contain specialized articles intended for small audiences.  Steven Harnad, a pioneer in electronic peer-reviewed journals, expects researchers to become their own e-publishers [3], and, indeed this is happening.  For example, the Los Alamos Physics Archive,, contains over 100,000 self-archived papers.  Also see the Open Archives Initiative,  (One can imagine a variation of the Napster music serving protocol,, for books and other material).


The Ebook has been long promised and slow to deliver, but it may be ready to emerge now.  That will depend upon evolving technology and the quality of design and engineering -- the technology will have to enable a transparent device and user interface.  As always, human and organizational issues will also constrain what we end up with and when we get it.  Adoption will be slower than Ebook proponents expect, because there are powerful, conservative social and organizational forces holding back change and the adoption of standards.  Yet, in the long run, the impact of the Ebook may be greater than they envision.  The Ebook will be more than a substitute Pbook.  What will be the social and psychological impacts on the generations of kids who first meet Spot and Sam on Ebooks in kindergarten?




1.    Bush, Vannevar, As We May Think, The Atlantic Monthly, July 1945,

2.    Betrisey, Claude, Blinn, James F., Bodin, Dresevic, Hill, Bill, Hitchcock, Greg, Keely, Bert, Mitchell, Don P., Platt, John C., and Whitted, Turner, “Displaced Filtering for Patterned Displays,” to appear, Proceedings SID 2000 Symposium,

3.    Harnad, Steven, Free at Last:  The Future of Peer-Reviewed Journals, D-Lib Magazine. December 1999,

4.    Illich, Ivan, In the Vineyard of the Text: a Commentary to Hugh's Didascalicon, University of Chicago Press, Chicago, 1993.


5.    Platt, John C., “Optimal Filtering for Patterned Displays,” Microsoft
Research Technical Report MSR-TR-2000-10,

6.    Press, Larry, "Portable Computers, Past, Present, and Future," Communications of the ACM, March, 1992.


7.    Press, Larry, "Emerging Dynabase Tools," Communications of the ACM, March, 1994.


8.    Quan, Margaret, Mutant bacteria, electronic ink and paper under development -- Offbeat technologies may hold key to displays, EE Times, August 24, 1998,

[1] For comparison, National Geographic Magazine is about 5.5 x 8.75 inches, the hardcover book I am reading 4.5 x 8.5, a small paperback 4.5 x 6, and an (old) Palm Pilot PDA 2.25 x 2.25.

[2] The signal processing algorithms that compute RGB intensities are derived from a model of human visual physiology and apply to any font and background colors or to an arbitrary image [2, 5]. 

[3] ITU, World Telecommunication Development Report, International Telecommunications Union, Geneva, 1999,

[4] A headset may be necessary for high quality speech, noise cancellation, voice recognition, and so forth.  That may not seem too stylish today, but styles change.  People with ear plugs and portable music players were once a novelty, but they are now taken for granted.

[5] See Illich [4] for an accounting of this evolution.

[6] Glassbook,, has a well-designed reader for the current, fixed page PDF format.

[7] When a document is saved as .lit, it will be marked up as an Open Ebook documented, then encrypted and compressed for security and storage efficiency.

[8] The potential is illustrated by Dataquest’s estimate that there are 19.2 million mobile PCs, 4.8 million palm-sized and 2.9 million pad format machines today.  They expect these figures to reach 33.8, 12.1 and 9.4 million in 2003.

[9] Adobe states they have shipped over 100 million copies of their Acrobat PDF reader.

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