Almost a year ago, Cary Lu, noted technologist and Macintosh author, died after a nine-month bout with cancer. In "Cary Lu Remembered" (TidBITS-399), I tried to convey who Cary was and a feeling for the memories he’d left for many of us.
In that article, however, I didn’t mention one final gift Cary left behind – a partially completed book about bandwidth that he was writing for Microsoft Press. He had completed much of it before his cancer was diagnosed, and although the radiation treatment and chemotherapy sapped his strength, Cary clung to the idea of finishing. His energy level visibly increased when he discussed the book, but despite valiant attempts, even Cary couldn’t finish a book while battling cancer.
Toward the end, I and Cary’s friend Steve Manes, then writing for the New York Times and now for Forbes, volunteered to finish the book. Although we harbored no illusions of being as qualified as Cary, we figured that between us we could tie together the final pieces. Steve spent hours talking with Cary and going over the notes for the chapter about Internet bandwidth, and Cary explained some of the finer points of audio and video bandwidth to me. In the end, though, we were on our own with a manuscript that might have been 80 percent done for Cary and his original schedule, but which was closer to 60 percent done for us, coming in as we did over a year after Cary had set down some of the chapters.
But Steve and I persevered, and digging deep within the Internet, we ferreted out details surrounding the history of bandwidth, satellite radio, and the many standards for television around the world. We merged and moved, edited and extended, and eventually we turned a manuscript into a book – The Race for Bandwidth ($19.99, Microsoft Press, ISBN 1-57231-513-X). Our editors at Microsoft Press came up with illustrations and summaries. And Cary’s wife Ellen W. Chu provided a humorous and touching foreword along with acknowledgments for all those who had helped not only with the book, but also with keeping Cary company during his illness.
About Bandwidth — The book itself contains eight chapters, the first four of which are essentially devoted to background information. It starts by describing what bandwidth is and why it’s crucial to our information age, then steps back to trace the history of bandwidth. The "Thinking about Bandwidth" chapter then looks at common misconceptions surrounding bandwidth, such as the fact that a slow boat has a higher raw bandwidth than a fast wire. That’s because bandwidth is the measure of the amount of information that flows from one place to another in a given amount of time, and sending a cargo ship with CD-ROMs from New York to London provides far greater bandwidth than the best Internet connection, even though the ship may take more than a week to make the crossing. The fourth of these background chapters delves into analog and digital bandwidth, looking at the advantages and disadvantages of each. In today’s increasingly digital world, many people think that digital is "better," whereas in fact, it’s difficult even to compare the two. For example, it’s easy to say that an audio CD sounds better than an analog cassette tape, but that comparison looks not at digital and analog but instead at examples of high and low bandwidth methods of carrying audio information.
Broadcast bandwidth, both audio and video, occupies the next two chapters, and coming at this from an Internet background, I found researching, editing, and updating these chapters to be fascinating. Cary covered existing types of broadcast bandwidth, as well as those that we’re likely to see in the future. For instance, digital satellite radio will start supplanting standard analog AM and FM radio in the next few years. In the United States, the FCC foresees perhaps 4 percent of the population being able to receive digital satellite radio broadcasts in the S band (2310-2360 MHz) by the year 2005. Just north of the U.S. border, however, Canada also plans to move to digital satellite radio but in the L band (1452-1492 MHz), with all existing analog AM and FM stations moving to digital satellite radio by the year 2010. Interestingly, Canada uses the S band for aeronautical telemetry applications, whereas the United States uses the L band for that purpose. It remains to be seen how this conflict will play out, but future radios may not work across the border.
Those interested in the Internet may find the final two chapters the most compelling. First, Cary looks at point-to-point bandwidth – standard telephone lines, dedicated Internet connections, cellular telephones, pagers, and faxes. Perhaps the most important lesson in this chapter is the difference between circuit-switched and packet-switched communications. In circuit-switched communications, such as a standard telephone call, you "own" the virtual circuit the telephone company creates for you: the full bandwidth of the call is devoted to your call. That ownership is important, because with voice communications, silence in the form of, say, a pregnant pause, has meaning. But when you’re transmitting and receiving digital data, the communications are inherently bursty: you receive a Web page, spend some time reading it, and then move on to the next one. In this situation, silence has no meaning, so it makes much more sense to share the bandwidth to even out the usage patterns. Such equality is achieved by breaking all communications into packets and sending each packet separately. The problem comes when you attempt to piggyback a packet-switched network like the Internet onto a circuit-switched network like the public telephone network.
Having described the background of how the wires work, Cary looks at how bandwidth works on the Internet itself. In many ways, this chapter is the linchpin of the entire book, since it seems that everyone wants to know more about how the Internet works. That said, I suspect that many Internet aficionados among the TidBITS audience may already know most of the good points Cary makes in this chapter, such as the numerous places in a standard Internet communication transaction that can act as bottlenecks.
Legacies — Steve and I volunteered to finish Cary’s book not just because of our friendship with him but also because we both felt strongly that the information in the book was too valuable to fade away into a dusty legal estate. My suspicion is that everyone will come to the book with some small amount of expertise – perhaps thanks to an interest in shortwave radio or the Internet. My hope is that everyone will leave the book having acquired at least a deeper appreciation for the issues surrounding information transfer in today’s world. I know I did: at times while researching some topic I’d stumble into Tonya’s office and quote a classic Far Side cartoon: "Mrs. Johnson, may I be excused? My brain is full."
Finally, as a gift for Cary’s children – Nathaniel Chu and Meredith Lu – some of us set up a Web site last year so that those whose lives had been touched by Cary could contribute their thoughts and remembrances. Our plan is to print the collection on acid-free paper for the kids. After a year, the time has come to work on the final output, but we want to give everyone a last chance to contribute before we commit to paper. The database itself will remain accessible as long as we can reasonably serve it and as long as Ellen desires, since, along with The Race for Bandwidth, his other books, editorial work, short films, and research, it has become yet another addition to Cary’s legacy.