Code: The Hidden Language of Computer Hardware and Software

An engaging and accessible exploration of how computers really work. The author breaks down complex concepts into simple, relatable explanations, making topics like binary, logic gates, and basic circuits far less intimidating. For newcomers, it’s a great way to build a foundational understanding of computer theory with just a touch of electrical engineering. As someone with a technical background, I still found it entertaining; the examples and analogies added fresh ways to frame ideas I already knew. It’s the kind of book that can bridge the gap between “I use computers” and “I understand what’s happening under the hood.” Highly recommended for anyone curious about what makes hardware and software tick, whether you’re starting from scratch or just want a new perspective.

I love how Charles wrote this book, I read it slowly throughout the year and was easily able to digest all the examples and illustrations provided and have got a better and broader understanding of Code, software, hardware, batteries, lightbulbs, history and much more!

Useful for readers who already have basic maths

Clear and entertaining

Disclaimer: I owned the first edition for years and read it a dozen times, mainly for pleasure since it’s not only informative but also just enjoyable to read. I’m a professional software architect and have dozens of textbooks on computer science and engineering so I’ve been around the block. This is the kind of book I would buy all for all my friends (if I had more than a couple) and family members (if they were even slightly into computers, which they aren’t sadly). Petzold does an exceptional job at describing digital logic and guides you through building a conceptual CPU from very first principles. I think his bottom up approach is the way to go and has helped me understand complex topics in an extremely simple way. When I’m not reading fiction, this is my go to bedtime reading. The second edition has about 100 more pages than the first and some content has been completely reworked and it’s great. If you ever had even a passing interest in knowing how computers work at a very fundamental level, get this book!

I never read the first edition of Code, but this seems to be an improvement. I'm only 100 pages in, but it is quite readable and I like the author's pace - though there's alot of material that's covered, the pace is relaxed and the reader usually won't feel overwhelmed. A minor flaw that I've noticed is that the physics underlying some of the engineering wasn't explained in detail, and that would've helped with regards to be being able to understand the circuits. On the whole, this book seems to be great, and I'd highly recommend it to programmers trying to understand the software-hardware interface.

I read the first edition of this book circa 2006. As a high school kid, I was already well versed in software but hardware and the way a CPU works felt like magic. I then read CODE and it forever changed my understanding of computers and how they worked at the lowest level. I consider it one of the most influential books I have ever read given at the time CS/EE wasn’t what it is today. Resources to learn this kind of stuff as an adolescent were scarce and or non-existent. I bought the second edition just to have it on my shelf.

If you want to learn computers, start here. Learning from a historical perspective removes complexity of trying to start with say GPUs - you learn just like computer engineers did, incrementally.

Im currently building my foundations in computers on a lower level one book at a time. I came into software engineering from a sales background. Over time, I’ve realised that while practical experience teaches you a lot, it can leave gaps in the deeper why behind how computers actually work and why software behaves the way it does. So I’ve been creating my own structured learning path to fill those gaps, starting from the ground up. The first book I chose is this one right here! It’s not a typical programming book. It starts with how humans first used codes to communicate through Morse code, telegraphs, and switches and slowly builds toward how those same ideas evolved into modern computers. What surprised me most is how much of computing is built on very simple logic. At its core, everything reduces to circuits making yes/no decisions and when you chain enough of those together, you get adders, memory, and eventually an entire processor. Reading it connected a lot of dots for me like how information becomes binary, how logic gates combine to perform arithmetic. It made computing feel less like magic and more like a long, logical sequence that starts with electricity and ends with the systems we work with every day. If you’re self taught, or you feel like you’ve jumped straight into frameworks and languages without really understanding what’s underneath, I’d highly recommend this book. It helped me see computers as one continuous chain of reasoning from Morse code to microprocessors.

Interessting, great book

One of the best, if not the best, books on computing… nice touch with the colored diagrams

Good concise write up on how hardware and software interact inside an Intel 8080 cpu.

Great book for a curious child or adult who wants to know how computers work. Less hands-on than Nisan and Schocken's book. Ideally, get both!