Preface to the Second Edition
The first edition of this book was published in September 1999. With much delight I realized that I had finally written a book that would never need revising! This was in stark contrast to my first book, which was about programming applications for Microsoft Windows. That one had already gone through five editions in just ten years. My second book on the OS/2 Presentation Manager (the what?) became obsolete much more quickly. But Code, I was certain, would last forever.
My original idea with Code was to start with very simple concepts but slowly build to a very deep understanding of the workings of digital computers. Through this steady progression up the hill of knowledge, I would employ a minimum of metaphors, analogies, and silly illustrations, and instead use the language and symbols of the actual engineers who design and build computers. I also had a very clever trick up my sleeve: I would use ancient technologies to demonstrate universal principles under the assumption that these ancient technologies were already quite old and would never get older. It was as if I were writing a book about the internal combustion engine but based on the Ford Model T.
I still think that my approach was sound, but I was wrong in some of the details. As the years went by, the book started to show its age. Some of the cultural references became stale. Phones and fingers supplemented keyboards and mice. The internet certainly existed in 1999, but it was nothing like what it eventually became. Unicode—the text encoding that allows a uniform representation of all the world’s languages as well as emojis—got less than a page in the first edition. And JavaScript, the programming language that has become pervasive on the web, wasn’t mentioned at all.
Those problems would probably have been easy to fix, but there existed another aspect of the first edition that continued to bother me. I wanted to show the workings of an actual CPU—the central processing unit that forms the brain, heart, and soul of a computer—but the first edition didn’t quite make it. I felt that I had gotten close to this crucial breakthrough but then I had given up. Readers didn’t seem to complain, but to me it was a glaring flaw.
That deficiency has been corrected in this second edition. That’s why it’s some 70 pages longer. Yes, it’s a longer journey, but if you come along with me through the pages of this second edition, we shall dive much deeper into the internals of the CPU. Whether this will be a more pleasurable experience for you or not, I do not know. If you feel like you’re going to drown, please come up for air. But if you make it through Chapter 24, you should feel quite proud, and you’ll be pleased to know that the remainder of the book is a breeze.
The Companion Website
The first edition of Code used the color red in circuit diagrams to indicate the flow of electricity. The second edition does that as well, but the workings of these circuits are now also illustrated in a more graphically interactive way on a new website called CodeHiddenLanguage.com.
You’ll be reminded of this website occasionally throughout the pages of this book, but we’re also using a special icon, which you’ll see in the margin of this paragraph. Hereafter, whenever you see that icon—usually accompanying a circuit diagram—you can explore the workings of the circuit on the website. (For those who crave the technical background, I programmed these web graphics in JavaScript using the HTML5 canvas element.)
The CodeHiddenLanguage.com website is entirely free to use. There is no paywall, and the only advertisement you’ll see is for the book itself. In a few of the examples, the website uses cookies, but only to allow you to store some information on your computer. The website doesn’t track you or do anything evil.
I will also be using the website for clarifications or corrections of material in the book.
The People Responsible
The name of one of the people responsible for this book is on the cover; some others are no less indispensable but appear on the colophon page at the very end of this book.
In particular, I want to call out Executive Editor Haze Humbert, who approached me about the possibility of a second edition uncannily at precisely the right moment that I was ready to do it. I commenced work in January 2021, and she skillfully guided us through the ordeal, even as the book went several months past its deadline and when I needed some reassurance that I hadn’t completely jumped the shark.
The project editor for the first edition was Kathleen Atkins, who also understood what I was trying to do and provided many pleasant hours of collaboration. My agent at that time was Claudette Moore, who also saw the value of such a book and convinced Microsoft Press to publish it.
The technical editor for the first edition was Jim Fuchs, who I remember catching a lot of embarrassing errors. For the second edition, technical reviewers Mark Seemann and Larry O’Brien also caught a few flubs and helped me make these pages better than they would have been otherwise.
I thought that I had figured out the difference between “compose” and “comprise” decades ago, but apparently I have not. Correcting errors like that was the invaluable contribution of copy editor Scout Festa. I have always relied on the kindness of copyeditors, who too often remain anonymous strangers but who battle indefatigably against imprecision and abuse of language.
Any errors that remain in this book are solely my responsibility.
I want to again thank my beta readers of the first edition: Sheryl Canter, Jan Eastlund, the late Peter Goldeman, Lynn Magalska, and Deirdre Sinnott (who later became my wife).
The numerous illustrations in the first edition were the work of the late Joel Panchot, who I understand was deservedly proud of his work on this book. Many of his illustrations remain, but the need for additional circuit diagrams inclined me to redo all the circuits for the sake of consistency. (More technical background: These illustrations were generated by a program I wrote in C# using the SkiaSharp graphics library to generate Scalable Vector Graphics files. Under the direction of Senior Content Producer Tracey Croom, the SVG files were converted into Encapsulated PostScript for setting up the pages using Adobe InDesign.)
And Finally
I want to dedicate this book to the two most important women in my life.
My mother battled adversities that would have destroyed a lesser person. She provided a strong direction to my life without ever holding me back. We celebrated her 95th (and final) birthday during the writing of this book.
My wife, Deirdre Sinnott, has been essential and continues to make me proud of her achievements, her support, and her love.
And to the readers of the first edition, whose kind feedback has been extraordinarily gratifying.
Charles Petzold
May 9, 2022