Rating: 
Summary: Wow. What a Book.
Review: Have you ever opened up the case of your PC, only to find that there are seemingly millions of lego-esque pieces stuck together? Have you ever wondered how computing went from the abacus to the Palm IV? Have you ever asked how the engineers are able to do the things they do?Well, ask no more. Instead, read this book. Charles Petzold is able to describe the workings of a simple computer, starting from the ground floor. He begins with descriptions of a simple circuit, and slowly works his way to more and more complex structures. You learn about flashlights, Morse code, and the early computers, and how each has impacted modern computing. Will this book teach you how to program? No. But if you were not a computer science major or electrical engineer in college, this book will lay some of the foundations for understanding this technology. The technical aspects get a little dense at times, but this did not detract from the impact of this book. If you have been curious about what goes on in that beige box, now is your time to investigate. This is the place to start.
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Summary: Excellent Book To Understand Computers at the Basic Level
Review: I am a computer programmer by trade and sincerely wish I had this book 7 years back when I started formal education. During my 4+ years in the higher education system, and even after, I and my classmates (later colleagues) were taught how to program computers (in various languages) and many of the higher level ideas in programming (Data Structures, Algorithms, Program Structure, Etcetera, Etcetera, Etcetera) but we never really learned how the computers worked inside. Even to many trained programmers, or at least me:), these beige boxes can be something of a magical black box which we don't really understand at a fundamental beyond the point of it processing the instructions we give it in our chosen programming language. In school I recieved perhaps one single semester course that attempted to teach how these things worked inside, yet that course still skimmed on the inner workings, the teacher instead spent his time on how monitors drew pixels on the screen and how laser printers worked.....
Looking back on it, I would blame the ignorance of the inner workings of computers that some programmers have on the decline of having to learn Assembly language (starting in the early nineties?), the lowest level programming language sans actual Machine Code, where one would be forced to deal with the raw inner workings of a computer naturally. I myself hope to learn it one day after reading this book :D Instead, I was taught the C programming language and what we learned in school became only more abstract in regards to the actual hardware...
This is where this wonderful book came into play. Since I recieved it half-a-year ago, it must have been read/devoured by me a dozen times or more - it goes from teaching the make-up of various codes (morse, braille, etcetera) to showing how some simple to understand concepts can be combined until a working computer, calculator, etcetera, can be built....... it gives one a great foundation for learning what Computer Science is all about or gives a newer-generation Programmer, like me, much needed knowledge on how that beige box basically works, on a hardware level!
The best thing is that those computer analogies can be finally thrown out the window - we all heard them before - like how "ram is like a table, or workspace. The bigger it is, the more things you can have ready and available at one time. The hard drive is like your drawers and cabinets. You can store more stuff there, but to use it, you have to take it out first and put it either on the table (RAM) or hold it in your hand (cache)." Petzold also uses analogies when he introdues topics but quickly moves beyond them, giving his audiences real understanding of the subject - which is very welcoming since analogies tend to explain function well but break down quickly when one is determined to learn more about a topic.
It is probably one of the few computer books on my shelf that can't get outdated and that's good, because it still will be there in 20 years.
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Summary: One of its kind...
Review: I am a general reader with 'some' interest in computer programming. I also have 'some' knowledge and interest about almost anything in this world. I found this book when I was looking for a programming related book in our local bookstore. I picked it up since it interested me initially due to its reference to morse code etc. I used to be intrigued by morse code (which I had found in one of my dad's telegraphy books) and used to even use it with a friend while keeping our language a secret. I must say that I found the book really amazing which is why I am writing the review. I also feel that it should be classified in more of general interest books (the bookstore had it under the software books as I mentioned earlier). I believe there might be other readers with general non-fiction interest who might miss this excellent opportunity just because they were not looking for some software book. Finally, I want to put a note of appreciation here for whoever designed the cover (I tried looking on the inside jacket). It is amazing while being strikingly simple. That is actually the first thing that caught my attention. Seems like a summary of all the design theories you ever read about. Highest degree of simplicity achieved by conscious thought and effort. Very intellectually provoking.
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Summary: WARNING: For hardcore geeks only!!!
Review: I am the manager of a computer store and a graphic/web designer and as such I use and troubleshoot computers every day and know rather a lot about them.
This book looked interesting because on the jacket it uses phrases like, "illuminating narrative" and "eminently comprehensible" and "no matter what your level of technical savvy".
In reality though after the 1st few chapters the book falls into an absolute quagmire of circuit diagrams and boolean logic tables and RAM address schemes and loses all sense of narrative or comprehensibility.
Unless you are really into math and/or are a programmer I would highly recommend AVOIDING THIS BOOK.
I am not a stupid person nor unfamiliar with computers but this was wayyyy beyond where I wanted to go with this. And my guess is that it's way beyond for most other folks as well.
If you are interested in learning how computers work I would highly suggest the series titled "How Computers Work" by Ron White.
(...)
'How Computers Work' contains very clear diagrams and explanations that while technical aren't at the picky and obtuse levels reached in the book 'Code'.
(...)
Rating:
Summary: Good
Review: I like this book very much.
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Summary: Best Book I've Read This Year
Review: I think that this is the best book that I have read all year. In some sense this is the book that I have been looking for for twenty-five years--the book that will enable me to understand how a computer does what it does. And--given the centrality of computers in our age--it has been a long wait. But now it is over. Charles Petzold (1999), Code: The Hidden Language of Computer Hardware and Software does a much better job than anything else I have ever seen in explaining computers--what they really are, and how they really work. Have you ever wondered just how your computers really work? I mean, really, really work. Not as in "an electrical signal from memory tells the processor the number to be added," but what the electrical signal is, and how it accomplishes the magic of switching on the circuits that add while switching off the other circuits that would do other things with the number. I have. I have wondered this a lot over the past decades. Yet somehow over the past several decades my hunger for an explanation has never been properly met. I have listened to people explain how two switches wired in series are an "AND"--only if both switches are closed will the lightbulb light. I have listened to people explain how IP is a packet-based communications protocol and TCP is a connection-based protocol yet the connection-based protocal can ride on top of the packet-based protocol. Somehow these explanations did not satisfy. One seemed like answering "how does a car work?" by telling how in the presence of oxygen carbon-hydrogen bonds are broken and carbon dioxide and water are created. The other seemed like anwering "how does a car work" by telling how if you step on the accelerator the car moves forward. Charles Petzold is different. He has hit the sweet spot exactly. Enough detail to satisfy anyone. Yet the detail is quickly built up as he ascends to higher and higher levels of explanation. It remains satisfying, but it also hangs together in a big picture. In fact, my only complaint is that the book isn't long enough. It is mostly a hardware book (unless you want to count Morse Code and the interpretation of flashing light bulbs as "software." By my count there are twenty chapters on hardware, and five on software. In my view only five chapters on software--one on ASCII, one on operating systems, one on floating-point arithmetic, one on high-level languages, and one on GUIs--is about ten too few. (Moreover, at one key place in his explanation (but only one) he waves his hands. He argues that it is possible to use the operation codes stored in memory to control which circuits in the processor are active. But he doesn't show how it is done.) Charles Petzold's explanatory strategy is to start with the telegraph: with how opening and closing a switch can send an electrical signal down a wire. And he wants to build up, step by step, from that point to end with our modern computers. At the end he hopes that the reader can look back--from the graphical user interface to the high-level language software constructions that generate it, from the high-level language software constructions to the machine-language code that underlies it, from the machine-language code to the electrical signals that load, store, and add bits into the computer's processor and into the computer's memory. But it doesn't stop there. It goes further down into how to construct an accumulator or a memory bank from logic gates. And then it goes down to how to build logic gates--either out of transistors or telegraph relays. And then deeper down, into how the electrons actually move through a transistor or through a relay and a wire. And at the end I could look back and say, yes, I understand how this machine works in a way that I didn't understand it before. Before I understood electricity and maybe an AND gate, and I understood high level languages. But the whole vast intermediate realm was fuzzy. Now it is much clearer. I can go from the loop back to the conditional jump back to the way that what is stored in memory is fed into the processor back to the circuits that set the program counter back to the logic gates, and finally back to the doped silicon that makes up the circuit. So I recommend this book to everyone. It is a true joy to read. And I at least could feel my mind expanding as I read it.
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Summary: If you are a geek you will love this book!
Review: If you are a geek you will love this book! As a programmer I found this book to be very interesting. I've read other reviews complaining that this book is for novice computer users, I completely disagree! Most developers work in a world of high level languages that completely abstract the inner workings of the computer's CPU and memory. This book manages to teach the reader the most basic elements of how a computer works starting with an intriging look at the basic physics of electricty and building up all the way to Assembly language. This book should be mandatory reading for all CS majors.
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Summary: Want to know exactly what a computer does?
Review: It's not often I willingly give money to Microsoft, but I bought this book in hardcover. I don't care if Petzold is a hardcore Windows guy or not; this book is as deserving of immortality as the Lions book or "Godel, Escher, Bach". Why? Because it lays it all out. Though it goes a bit light on the actual electronics, preferring to focus on the telegraph relay as its main way of understanding what's going on, this book takes the reader from square one -- sending messages to a friend with a flashlight -- to the structure of a modern microprocessor. It's an incredibly detailed yet easily accessible look at the internals of a computer system. Flaws? A couple -- no index, and as I said it gives short shrift to what may be the single biggest invention of the 20th century, the transistor. But by and large Petzold has written the ultimate book to explain the mysteries of the computer to the layperson. This book is a must-buy.
Rating: 
Summary: Information in easy to digest chunks
Review: It's not often that you come across a book that deals with complex topics in language that the layman can understand. The organisation is excellent - Petzold explores one topic at a time, giving you the chance to absorb one concept before moving on to the next. And each chapter builds on what you have read before. If you are just curious about what goes on inside your PC, or if you are involved in IT but lack an understanding of the actual box that does all the work, then this book is for you.
Rating:
Summary: well duh!
Review: ones and zeros the answer is !42
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