Customer Reviews

Code (DV-MPS General)

5 star:		(81)
4 star:		(14)
3 star:		(3)
2 star:		(1)
1 star:		(2)

 

 

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.

The average person who uses a computer to surf the web or type letters has so little knowledge of the underlying technology he or she is using that it may as well be magic. Even programmers, who typically spend their days solving problems with the high-end abstractedness of object-orientation, may be more than a little unclear about what's actually going on inside the box when their compiled code is running.

Petzold attempts, and largely succeeds at, writing a book that leaves the reasonably intelligent layperson with a thorough comprehension of each layer that comprises a modern electronic computer (binary coding -> electronic representation -> transistors -> logic gates -> integrated circuits -> microprocessors -> opcodes -> assembly language -> high-level language -> applications). At times, the reader must follow along carefully, but Petzold tries to avoid needless complication.

Code is a well written and very entertaining explanation of the digital electronic technology that has become an integral part of our daily lives. Short of getting a degree in electrical engineering, this book is your best bet to understand how it works.

Charles Petzold a does an outstanding job of explaining the basic workings of a computer. His story begins with a description of various ways of coding information including Braille, Morse code, and binary code. He then describes the development of hardware beginning with a description of the development of telegraph and relays. This leads into the development of transistors and logic gates and switches. Boolean logic is described and numerous electrical circuits are diagramed showing the electrical implementation of Boolean logic. The book describes circuits to add and subtract binary numbers. The development of hexadecimal code is described. Memory circuits are assembled by stringing logic gates together. Two basic microprocessors are described - the Intel 8080 and the Motorola 6800. Machine language, assembly language, and some higher level software languages are covered. There is a chapter on operating systems. This book provides a very nice historical perspective on the development of computers. It is entertaining and only rarely bogs down in technical detail.

The book starts out very solid, describing all the building blocks of a computer. The beginning is the best book I've seen so far describings everything from the binary system to electrical circuits, to gates to simple calculators, to memory, to a complete machine with a "control panel". But after that, the book started getting a LOT more broad (not necessarily a bad thing). It seems almost as if Petzold wanted to tell you everything about the world of computers, but couldn't fit it in a book such as this; so he dabbed a little here and there of a few terms, history, etc... (allowing you the option to look up anything you wanted if you had the interest).

My oppinion is that the book is _great_ up to about the middle of the book, after which he just condenced all the rest of the information which would otherwise takes thousands of pages to describe in as much details as he described how to build a physical logic machine... I think that if someone isn't a "techie" or isn't in the computer field, they may have some hard time understanding a few minor points... but overall, this is a GREAT book.. one of a kind.

Greatly recommended for everyone's library... I can honestly say, I always told people "a computer is nothing more than zero's and one's"... but until I read this book, I couldn't BUILD one... now I can (given time! :).

P.S. This book is perfect for those who didn't necessarily go to college and learned everything on their own... it covers some CS, CE, and EE. Those who went to college with either of those majors probably learned the greatest part of this book... but it's a great 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.

This book cleared up some fuzzy areas that I have always been interested in but never really had the time to pursue. I have been developing software since 1980, and got this book because of the sample chapter that I read from the MS website. Now that I have read the book, I am able to better understand the electrical system on my plane (a surprise side effect of reading the book, I expected it to be more high level)

I would recommend this book to all software developers, and also anyone that has any technical hobbies. It has much technical information, but is also very easy to read.

Steve

Yes, that's right! CODE is the greatest book on the face of the earth!
Why? Here's my story, and go judge for yourself.
I'm using computers for around four years. My question was always "How is this thing doing it's stuff?". Although I have no idea how other electronic stuff work, the computer did bothered me more then anything else because the computer seems to do some kind of THINKING, that's why it triggered my THINKING. This question kept on staying in my head until two weeks ago. It really bothered me. All along this four years I was looking for an answer to my question. I bought books, went to the library a thousand times, but nothing helped me. I learned a few programming languages along my journey, but it did not clarify how it really works. So I decided to learn Assembly Language because I taught that that's where I'm going to find the answer to my question. I must admit that it did helped me out quite a bit, but not to the extent I expected. I used a great book called "Assembly Language Step-by-Step" by Jeff Duntemann, which is a great book, but since the subject of the book is not to teach you how computers work, it didn't helped me enough to satisfy my desire for the answer to my question. I contacted Jeff Duntemann, the author of the book and I told him my problem. He referred me to this book CODE. So I rushed and bought this book. The rest of the story is self-understood, the book made my day and my life. And that's why I'm restating "This is the greatest book on the face of the earth".

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.

This is a fascinating book on many levels. Extremely well written. For anybody who uses computers in their work and always wondered what goes on under the covers, this book touches on just about every area and goes into great detail in some areas.

On the other hand, don't buy this book if you want practical information about how to be a better programmer or whatever. This book is definetely suited to an enthusiast who is honestly interested in learning arcane details. It isn't going to help anyone get a higher salary or a promotion.

That's what I really liked about this book. It was truly different from any other book you will ever buy from Microsoft Press or like publishers.

My only real critiscism is that it seems to run out of steam at the end. Chapter after chapter is devoted to the inner workings of logic gates, memory, and so on, but almost nothing is said about operating systems.

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.