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How Computers Really Work: A Hands-On Guide to the Inner Workings of the Machine

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From Amps to Apps: How Computers Work is an approachable, hands-on guide to understanding how computers work, from low-level circuits to modern software.

From Amps to Apps: How Computers Work takes an informal approach to topics often reserved for textbooks. Each chapter covers one foundational aspect of computing. Exercises and hands-on activities throughout are designed to help the reader learn. Exercises mostly involve mental problem solving, while hands-on activities require the reader to actually try various aspects of computing: building a circuit, writing software, and so forth.

Readers will learn about electrical circuits, learn how to read a circuit diagram, and build a working circuit. They'll learn how computer hardware like processors, memory, and input/output work and fit together; how low-level machine code runs on a processor, and how to examine the machine code of software running on a computer. They'll gain an understanding of the differences between programming languages like C and Python; examine operating systems; use tools to explore their local network and the Internet, and build a simple web page. The book's primary goal is to give the reader a broad understanding of how computers work; to offer a big picture view of computing and the foundational information needed to dig deeper into topics that interest them.

393 pages, Kindle Edition

Published December 29, 2020

161 people are currently reading
487 people want to read

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Matthew Justice

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Displaying 1 - 18 of 18 reviews
Profile Image for David.
Author 1 book121 followers
April 12, 2022
I enjoyed the evergreen material in the first half of this book, which takes us from transistor logic to high-level programming. As for the second half, I can't really disagree with the choice of the "cloud" and "app" material since that's what people probably think of in terms of modern computing...but it felt insubstantial and fad-ish compared to the earlier material. (Because it IS insubstantial and fad-ish!)

The really stand-out feature are the activities. This book covers a vast scope of material and being able to put ALL of it into hands-on practical experience is a brilliant move.

I bought this book to read to my kiddos (and that's exactly what I did - it came after the regular bedtime story). I think it's an amazing resource for young audiences. I would have given my right arm for this breadth of coverage when I was at the right age for it. But really, this would be incredible for anyone with a curiosity about computers.

I'm still a huge, huge fan of "The Pattern on the Stone" by Hillis, which packs an incredible amount of lucid explanation in a tiny package. But now I also have a book to recommend with practical exercises. I also think the use of the Raspberry Pi is right on the mark - I love the idea that we have a cheap, common teaching instrument that is a REAL computer that is itself available for less than the price of a book. It's a perfect combo.
Profile Image for Mahshid Parchami.
95 reviews24 followers
April 8, 2022
یه کتاب عالی برای درک عملکرد کامپیوترها؛ از صفر و یک تا ترانزیستور، مدار منطقی، زبان ماشین و مباحث زیاد دیگه
حدود یک سوم کتاب پروژه های عملیه که من انجام ندادم. الان تا حدی میفهمم که کامپیوتر چطور صفر و یک رو میخونه و دستورات رو میفهمه و انجام میده :) البته تقریبا
Profile Image for jhenu.
2 reviews
January 27, 2022
I’m an Engineer, this book is the missing link between theories learned in your curriculum and work.
Profile Image for Renato Pires.
28 reviews1 follower
February 9, 2023
I loved this book! I learnet a lot about computers behind the screen!
Author 18 books2 followers
August 28, 2022
Well written and with a lot of good exercises to do, but I felt it skipped over the part of how computers really work that's most mysterious -- how do you actually make them programmable? The description of the basic logic gates and how they can be implemented with transistors is very clear, but it then jumps straight to "the CPU pulls an instruction from memory and implements it" -- how does it do that? We go straight from something that's 100% hardware to something that seems disconnected from it. This isn't a flaw unique to this book, of course, but it promises to go from amps to apps and that's a big hole in enabling the reader to fully understand how computers actually work.

(Also, the discussion of voltage drops and high-low measurements raises a question the text doesn't answer. Say 5v is high and 0v is low and you have a circuit with three gates in it. Then for all three gates to indicate high you need a total of 15v in the circuit. But if only one is high, and the voltage drop across that gate is 5v, where do the other 10v go that were present if the other two gates were high? Do we need a "mirror circuit" of some sort that manages the voltage that isn't being used to represent information in the main circuit? This isn't a topic I really know anything about but it would have been good for the question to be addressed).
Profile Image for Antoni Heba.
11 reviews
July 18, 2025
This book is gold. Ideal for someone interested in computers, without formal computer science education, and willing to make a deep dive. I fit the description and I enjoyed every page of it.

The subtitle say it all: 'a hands-on guide to the inner workings of the machine'. It's a guide because it starts from the basics like binary and logic, then goes to electronics, building on every chapter till it closes with modern computing. The style is simple, clear, and concise.

It's hands on because almost every chapter ends with projects to put knowledge to work and get hands dirty. It was with great pleasure that I build elecritcal circuits, adders, couters, and then moved to coding basics: assembly language, C, Python, HTML, CSS, Javascript. It also made me discover Raspberry Pi.

Rarely do I sumble upon the book I was just looking for. It reignited my interest in the machine.
Highly recommended.
2 reviews
November 17, 2024
How Computers Really Work is a well-structured and informative book that provides an accessible introduction to the inner workings of computers. It breaks down complex concepts into digestible explanations, making it a valuable resource for beginners or those looking to refresh their knowledge.

However, the writing style occasionally detracts from the experience. The author frequently uses phrases like “if you look at,” which can feel repetitive and, at times, disrupt the flow of the text. While these phrases aim to guide the reader, their overuse might make the explanations seem more drawn-out than necessary.
47 reviews
October 8, 2023
tl;dr It's the Noam nand2tetris book, but uses Python instead.

I can't get through this book. It's the logic chapters in the beginning. There a bunch of these nand2tetris type books.

This book is if you wanted to use Python instead of Java in the Noam book, which I also couldn't get through the logic chapters.
3 reviews
November 22, 2023
An excellent text that achieves the goal set out by it: to be an easy entry into some big topics around computers. I especially enjoyed the exercises in this text. I would say the exercises don't pose much of a challenge, except for when an additional challenge is tacked on and left to the reader; the exercises are more of a "follow along" kind of ride.
Profile Image for Ben.
2,734 reviews228 followers
May 7, 2022
Deep down, from my years of schooling, I knew all of this book's details.
But, it is put together so well! It was a fun refresher and an interesting book.

Would recommend to learn about the innerworkings of a computer!

4.8/5
Profile Image for Tomi J. Astala.
1 review
January 29, 2023
This book provides introductions to a wide variety of topics: electronics-, logic-, machine language and assembly-, programming-, and networking of computers.

This is a good read if you want to know simple basics and what topic(s) to learn more about.
Profile Image for Sinan.
3 reviews
March 2, 2025
Grokked this thing over the weekend.

Very clear, concise and informative! Although we’re left asking for more depth at times, the author has covered a great breadth of fundamental computer science/engineering topics.

New edition with machine learning/AI coverage could be interesting!
18 reviews
June 5, 2024
Very good read for beginners. The way in which the author explains every topic is superb. A must read for those who are interested in computer science
Profile Image for Adam.
65 reviews
December 7, 2024
It's easier than ever to find and use computers, but few people today really understand how computers work.
Profile Image for Anna Xu.
54 reviews
December 17, 2024
the last computer science book i will read in a while, hopefully.
Profile Image for byte.
27 reviews
May 12, 2025
I wanted to find a beginner book for a starter newbie friend of mine. Judging by the cover I thought it would be a very basic surface level read. But I was wrong completely and I'm so glad. Everything was written simply, concisely, to the point. Also there are some questions, projects, ideas and exercises accompanying the chapters. I wish we started it all with books like this. We scraped the shitty web, old books, no mentors and unhelpful professors in order to get here.
Displaying 1 - 18 of 18 reviews

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