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Code: The Hidden Language of Computer Hardware and Software

4.40  ·  Rating details ·  7,382 ratings  ·  610 reviews
What do flashlights, the British invasion, black cats, and seesaws have to do with computers? In CODE, they show us the ingenious ways we manipulate language and invent new means of communicating with each other. And through CODE, we see how this ingenuity and our very human compulsion to communicate have driven the technological innovations of the past two centuries.

Kindle Edition, 400 pages
Published (first published September 29th 1999)
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Matthew Hayes This book pretty quickly gets into electricity and basic circuits.
As you get further into the book, it gets very technical, to the point where you are…more
This book pretty quickly gets into electricity and basic circuits.
As you get further into the book, it gets very technical, to the point where you are actually building a computer and programming it.

There isn't any math, but definitely electronics and computer science.

I would not recommend this if you "in general have no inclination towards the sciences".(less)
Dan Drake I read the Kindle version, and it's fine. A couple things don't quite work, though: there are a lot of large-ish tables and sometimes flipping the pag…moreI read the Kindle version, and it's fine. A couple things don't quite work, though: there are a lot of large-ish tables and sometimes flipping the page past them requires being careful about where you tap/swipe (I have a Paperwhite).

There's also a bit on fonts and typefaces, and the text in that section all appears identical even though it's clear that in the print version, it's different.

So, the Kindle version isn't a perfect version, but I'd say it's "comfortable" and perfectly readable. If you have a Kindle and want to read this book with it, go ahead. It's a good book.(less)

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Aug 14, 2011 rated it it was amazing  ·  review of another edition
I'll be honest. I only read this book because it was quoted as a must read by Joel Spolsky on a stackexchange answer about how to go about learning programming (and finding out if you want/should be a programmer).

I was a little hesitant due to the year of release. Being at least some 11 years old that's a lot of time in the tech world. Ultimately though that doesn't matter. I defy any developer/programmer/system builder to read this book and not blitz through it lapping it up. Yes if you've done
My opinion on this book is really divided : on the one hand I enjoy some chapters, on the other hand I hardly managed to restrain myself from flipping through other chapters. Basically, this book designs and builds a basic computer by introducing in each chapter a concept or a technology used inside computers. It was written from 1987 to 1999, consequently one shouldn't expect any description of newest technologies.

It starts really slowly with the first chapters, but then things get more and mor
Cardinal Biggles
Raise your hand if you think metaphors and analogies should be used sparingly. I'll raise my hand with you. This book is for us.

After reading this book, I can see behind the pixels on my computer screen. I know what I'm really looking at. So many layers of abstraction are removed by learning about how logic gates can be arranged as processors and RAM, how code is simply a representation of those microscopic switches being flipped, and how pixels are simply a graphical interpretation of the state
Yevgeniy Brikman
Every single person in tech should read this book. Or if you're just interested in tech. Or if you just want a basic appreciation of one of the most important technologies in human history—the computer.

This book contains the best, most accessible explanation I've seen of how computers work, from hardware to software. The author manages to cover a huge range of topics—electricity, circuits, relays, binary, logic, gates, microprocessors, code, and much more—while doing a remarkable job of gradual
Dec 03, 2009 rated it it was amazing  ·  review of another edition
Recommends it for: nerds, geeks, smarty pants
Shelves: development
Electricity is like nothing else in this universe, and we must confront it on it's own terms. That sentence, casually buried near the beginning of the book, exemplifies the engineer's muse: a striving to become aware of the inhuman, how it operates, and to find means of creating a socket for human enterprise, something to extend the fallible chassis of our flesh.

The first two-thirds or so of this book follows a double track. One track covers the ways in which meaning may be encoded into messages
Alex Palcuie
Apr 06, 2013 rated it it was amazing  ·  review of another edition
Shelves: favorites
If you work with computers and didn't read this book, you are lame. ...more
Igor Ljubuncic
Jun 28, 2018 rated it it was amazing  ·  review of another edition
Shelves: software
This is a great book. Surprisingly interesting.

While the subject matter is not a new thing to me - far from it - the way the author goes about telling the story of how modern computers came to life is exciting, engaging and fun. He starts with morse and braille, talks about the principles of mathematics and information, explains the critical concept of switches, and finally moves into the world of circuit boards and binary data, cultimating in ALU. After that, he discusses the idea of analytical
Feb 28, 2012 rated it really liked it  ·  review of another edition
I have been an IT professional for 20 years, but I never knew what the switches on the front panel of the Altar computer were for. I do now.

In fact, because of this book, I know many things about how a computer really works that I never did before. I think this book is great for anyone, except Electrical Engineers who would be bored. Having some background in computers probably makes this book easier to get through, but Petzold assumes nothing and starts from scratch. He does a good job of makin
Jan Martinek
Aug 08, 2016 rated it it was amazing  ·  review of another edition

What a ride! A book about computers “without pictures of trains carrying a cargo of zeroes and ones” — the absolute no-nonsense book on the internals of the computer. From circuits with a battery, switch and bulb to logic gates to a thorough description of the Intel 8080. Great way to fill blanks in my computer knowledge.

The book takes the approach of constructing the computer “on the paper and in our minds” — that's great when you're at least a little familiar with the topic, maybe not so when

Miranda Sikorsky
It is a great book, I demystified some thoughts I had about software architecture.
Alex Telfar
Mar 23, 2018 rated it it was amazing  ·  review of another edition
Shelves: not-at-library
Very close to my ideal book. Starts from understandable foundations and builds from there. Charles doesnt try to explain through high level metaphors (that do a poor job of capturing the truth -- I am frustrated after picking up another apparently interesting physics book only to find it contains no math), rather, he slowly builds on simple examples. And while it does get pretty complex, Charles doesnt avoid it. !!!

For a while I have been frustrated about my understanding of computers. I underst
Mar 05, 2009 rated it it was amazing  ·  review of another edition
I LOVE this book. I regard myself an innocent computer illiterate. And Petzold helps me to walk inside an electrical circuit, a telephone, a telegraph, an adding machine, a computer, and to understand the basics behind the design, of what is going on inside. I start getting the math, the logic behind all this technology that has become pretty much the center of my life today. And I should understand the logic behind the center of my life, right?

What is so good about this book: it is written in
Aug 01, 2010 rated it really liked it  ·  review of another edition
This book basicaly tries to take you from the very basics of how to encode information, such as how binary is used to represent complex information, to understanding how a computer uses information like this to perform intricate operations. The route between those two points is the interesting part, and there was some parts that I foudn really illuminating and important. For example, I didn't understand hexadecimal numbers (or indeed what base 4, base 8, etc) numbers meant before I read this boo ...more
Carlos Martinez
Mar 06, 2019 rated it it was amazing  ·  review of another edition
Shelves: science
Such a fun and interesting book. Petzold goes back to the very basics to explain how to build a computer (of sorts) from the ground up. First he explains binary (via morse code and Braille), then he introduces relays and switches, then gates and Boolean logic, and before you know it you're building an electronic counting machine. He continues with a potted history of transistors, microchips, RAM, ROM, character encoding and all sorts of other fun stuff.

I skipped over some pages, because I don't
Apr 04, 2017 rated it it was amazing  ·  review of another edition
Shelves: byte-me
Wow. I wish I had had this book back when I was taking my first Computer Architecture course in college! It carries you along from the very fundamentals of both codes (like braille) and electric circuits in the telegraph days all the way to the web in a way that even a layperson could understand, with plenty of verbal and diagrammatic explanation. It does at points get pretty deep into the weeds but I really appreciated the author's efforts to provide such an exhaustive dive into how computers w ...more
Laura Marelic
May 19, 2020 rated it it was amazing  ·  review of another edition
This book is the perfect depth for novices but also people who are “in tech” and don’t really understand how it all works (like me). I can now look around at all the electronics in my house and feel like I know what’s fundamentally going on. Knowledge is empowering! The last chapter of the book felt a bit rushed and ended abruptly, but maybe that’s just my wanting the book to go on longer/end at present day. Overall, I loved it and will surely be recommending it to anyone who asks how computers ...more
Rik Eberhardt
Jun 14, 2008 rated it really liked it  ·  review of another edition
In brief: be prepared to skim through at least 25% of this book! If I had this book in a seminar freshman year, I might have completed the Computer Science program. In a very fun manner, this book presents 3 years of introductory CS curricula: discrete structures, algorithms, logic gates, ... After reading this during two cross-country flights, I better understand (and remember) classes I took 10 years ago. Almost makes me want to try again (*almost*).
This book has really taught me a lot, despite the fact that many of the later chapters lost me somewhat; it felt like it became much more complicated and hard to follow after the earlier chapters, which were great, slowly paced and well explained. While Petzold does assume the reader is starting from scratch, I think it would be easier to follow later on if you had some background in computers/technology. As it was, I had to bombard my dad (an electronic engineer) with questions to even make it ...more
Martin Lumiste
Feb 24, 2021 rated it it was amazing  ·  review of another edition
What an absolute gem I found in some Stack Overflow comments! Deriving modern computers from first principles such as Morse code and electromagnets, it's a rare book that can connect with you regardless of prior technical expertise.

Would mostly recommended for software professionals looking to ground themselves in how it all started. This doesn't mean it's a history book: the insight into hardware and software components is as relevant today as it was in 2000.

Truly enjoyable read throughout.
Alisa Mansurova
Nov 25, 2019 rated it it was amazing  ·  review of another edition
Just finished reading my b-day gift, the 'Code' by Charles Petzold - probably the best engineering book I've ever read. By saying 'engineering', I mean it. Unlike other computer science books, the 'Code' teaches how computers work in a nutshell. It leads you from the very basics like morse & braille codes to boolean algebra and various numeric systems, from simple tiny electric circuits which bulb the lamp to primitive adding machine (built from relays, hehe), up to history of development and en ...more
Mark Seemann
Jun 28, 2018 rated it really liked it  ·  review of another edition
Shelves: software
Since I loved Charles Petzold's The Annotated Turing: A Guided Tour Through Alan Turing's Historic Paper on Computability and the Turing Machine, I wondered if he'd written other books about the foundations of computer science. Code seemed like an obvious candidate.

This book explains, in as much details as you could possibly hope, and then some, how a computer works.

Since I've been a professional software developer for about two decades, the title of the book, Code, gave me an impression that it
Michał Wilczyński
So I've reread this book once more because I felt it was great, yet I could not give it 5/5 before.
And I'll keep my 4/5, same as it was rated before.

Generally the content of this book is great and introduces fundamentals of why and how things work in computers.
But... I have a feeling that author tried to target two disjoint audiences: people who have little knowledge of computers at all and power users who will connect current knowledge about computers with new facts from this book, experiencin
Feb 16, 2017 rated it really liked it  ·  review of another edition
I really enjoyed most of this book. The slow unfolding of how computers are built actually work was extremely fascinating - from simple lightbulb circuits to logic gates to RAM to keyboards and monitors. Unfortunately, parts of this book seem quite dated (most anything discussing "contemporary" technology, i.e. 1990s computers) and the final chapter on the graphical revolution goes through way too much, way too fast to be of any use. A few chapters were tempting to skim For example, Petzold incl ...more
Trevan Hetzel
Jan 13, 2013 rated it it was amazing  ·  review of another edition
With a desire to learn how the high level code (HTML, CSS, JavaScript, etc.) I write on a daily basis actually makes its way through the magical land that is a computer and returns pleasantries to a human being behind the screen, I sat down with this "Code" book. The book is very intriguing from the start, beginning with the earliest forms of code (Morse, Braille, etc.). Petzold spends a long time laying down the basic blocks of electrical engineering before progressing to how bits flow through ...more
Feb 02, 2012 rated it it was amazing  ·  review of another edition
There's a long, long list of books where my common reaction to them is "I wish I'd read this in high school, it could've set me straight much earlier!" Unfortunately, this isn't one of them... because I graduated in 1998 and this was published in 1999.

At some point in your computer science career, you will take a courses and labs in digital systems. At Stevens, when I was your age, this was 381 (Switching Theory and Logical Design) and 383 (Computer Organization). This book combines both of thos
Ieva Gr
Dec 31, 2018 rated it really liked it
Shelves: technical
The book reminds me of the courses that students usually have during the first year of the University. It provides a general overview of how computers function. Starting from workings of an electrical circuit and building up to various logical elements with gradually increasing complexity. It also discusses some relevant historical moments as a typical professor in a typical lecture would do and ends with a broad overview of personal computers as they were in 1999.

The summary on the back of the
Jun 06, 2011 rated it really liked it  ·  review of another edition
This was a wonderful non-fiction read, especially the first 15 or so chapters. Chapter 17 ("Automation"), however, was where I began to feel a bit in over my head. While that chapter was fairly thorough, when I got to later chapters and realized I couldn't quite grok what was going on in these chips, it was hard for me to tell whether I was holding myself back by not fully understanding the concepts of Chapter 17, or if Petzold was simply glossing over some of the details that might have clued m ...more
This book is quite incredible. You start with braille and simple light switches, make your way to oscillators, flip-flops and multiplexer, and suddenly you understand how computer hardware works. And that's coming from someone who already thought they "sorta" understood how it worked. I didn't really. Now I do. Best bottom-up education ever. ...more
Travis Johnson
Sep 10, 2009 rated it it was amazing  ·  review of another edition
I really, really truly love this book. The beginning is slightly slow, but after the 1/3 mark or so, I couldn't put it down(literally. hello, 5am.)

I probably learned more about architecture from this book than the quarter in my Architecture & OS class at university.
Randall Hunt
Feb 22, 2011 rated it it was amazing  ·  review of another edition
Recommends it for: CS Majors, Everyone
Shelves: all-time-greats
Definitely one of the greats. If not already, it soon will be, a staple of computer science literature. It's both a narrative history of Computer Science and a brilliant introduction to systems and programming. This book should be a pre-requisite for introductory CS classes. ...more
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Charles Petzold has been writing about programming for Windows-based operating systems for 24 years. A Microsoft MVP for Client Application Development and a Windows Pioneer Award winner, Petzold is author of the classic Programming Windows, currently in its sixth edition and one of the best-known programming books of all time; the widely acclaimed Code: The Hidden Language of Computer Hardware an ...more

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124 likes · 46 comments
“Code is not like other how-computers-work books. It doesn't have big color illustrations of disk drives with arrows showing how the data sweeps into the computer. Code has no drawings of trains carrying a cargo of zeros and ones. Metaphors and similes are wonderful literary devices but they do nothing but obscure the beauty of technology.” 10 likes
“In 1948, while working for Bell Telephone Laboratories, he published a paper in the Bell System Technical Journal entitled "A Mathematical Theory of Communication" that not only introduced the word bit in print but established a field of study today known as information theory. Information theory is concerned with transmitting digital information in the presence of noise (which usually prevents all the information from getting through) and how to compensate for that. In 1949, he wrote the first article about programming a computer to play chess, and in 1952 he designed a mechanical mouse controlled by relays that could learn its way around a maze. Shannon was also well known at Bell Labs for riding a unicycle and juggling simultaneously.” 3 likes
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