Understanding the Digital World: What You Need to Know about Computers, the Internet, Privacy, and Security - Hardcover

Kernighan, Brian W.

Hardcover

ISBN 10: 069117654X ISBN 13: 9780691176543

Verlag: Princeton Univers. Press, 2017

Inhaltsangabe

Understanding the Digital World explains how computer hardware, software, networks, and systems work. Topics include how computers are built and how they compute; what programming is and why it is difficult; how the Internet and the web operate; and how all of these affect our security, privacy, property, and other important social, political, and economic issues. This book also touches on fundamental ideas from computer science and some of the inherent limitations of computers. It includes numerous color illustrations, notes on sources for further exploration, and a glossary to explain technical terms and buzzwords. Understanding the Digital World is a must-read for all who want to know more about computers and communications. It explains, precisely and carefully, not only how they operate but also how they influence our daily lives, in terms anyone can understand, no matter what their experience and knowledge of technology

Über diesen Titel

Über die Autorin bzw. den Autor

Brian W. Kernighan is a professor in the Department of Computer Science at Princeton University. He is the coauthor of ten other books, including the computing classic The C Programming Language (Prentice Hall). He lives in Princeton, New Jersey.

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"This is the clearest and simplest explanation of the world we now all depend on--how it works and why it does what it does—from one of our best-known inventors. Everyone on Earth needs to read it."—Eric Schmidt, executive chairman of Alphabet Inc. and Google

"This book takes the mystery out of computers and the Internet, and everyone can learn from it. With a friendly and accessible style, Kernighan connects what is happening inside machines to the news of the day and developments about the digital world."--Harry Lewis, coauthor of Blown to Bits: Your Life, Liberty, and Happiness after the Digital Explosion

"Kernighan tells us exactly what we need to know about computers and computer science, focusing on ideas that are useful and interesting for everyday computer users. He covers a fascinating range of topics, including fundamentals such as computer hardware, programming, algorithms, and networks, as well as politically charged issues related to government surveillance, privacy, and Internet neutrality."--John MacCormick, Dickinson College

"Understanding the Digital World provides a broad overview of computers and electronic communications for a general audience. The book flows smoothly from topic to topic, and readers from diverse backgrounds will find it accessible."--Bryan Respass, Bergen County Academies

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Understanding the Digital World

What You Need to Know about Computers, the Internet, Privacy, and Security

By Brian W. Kernighan

PRINCETON UNIVERSITY PRESS

Copyright © 2017 Princeton University Press
All rights reserved.

ISBN: 978-0-691-17654-3

Contents

Preface, xi, 
Introduction, 1, 
Part I: Hardware, 7, 
1. What's in a Computer?, 11, 
2. Bits, Bytes, and Representation of Information, 23, 
3. Inside the CPU, 37, 
Wrapup on Hardware, 51, 
Part II: Software, 53, 
4. Algorithms, 55, 
5. Programming and Programming Languages, 67, 
6. Software Systems, 87, 
7. Learning to Program, 105, 
Wrapup on Software, 117, 
Part III: Communications, 119, 
8. Networks, 125, 
9. The Internet, 141, 
10. The World Wide Web, 163, 
11. Data and Information, 183, 
12. Privacy and Security, 203, 
13. Wrapping Up, 217, 
Notes, 221, 
Glossary, 227, 
Index, 233, 

CHAPTER 1

What's in a Computer?

"Inasmuch as the completed device will be a general-purpose computing machine it should contain certain main organs relating to arithmetic, memorystorage, control and connection with the human operator."

Arthur W. Burks, Herman H. Goldstine, John von Neumann, "Preliminary discussion of the logical design of an electronic computing instrument," 1946.

Let's begin our discussion of hardware with an overview of what's inside a computer. We can look at a computer from at least two viewpoints: the logical or functional organization — what the pieces are, what they do and how they are connected — and the physical structure — what the pieces look like and how they are built. The goal of this chapter is to see what's inside, learn roughly what each part does, and get some sense of what the myriad acronyms and numbers mean.

Think about your own computing devices. Many readers will have some kind of "PC," that is, a laptop or desktop computer descended from the Personal Computer that IBM first sold in 1981, running some version of the Windows operating system from Microsoft. Others will have an Apple Macintosh that runs a version of the Mac OS X operating system. Still others might have a Chromebook or similar laptop that relies on the Internet for storage and computation. More specialized devices like smartphones, tablets and ebook readers are also powerful computers. These all look different and when you use them they feel different as well, but underneath the skin, they are fundamentally the same. We'll talk about why.

There's a loose analogy to cars. Functionally, cars have been the same for over a hundred years. A car has an engine that uses some kind of fuel to make the engine run and the car move. It has a steering wheel that the driver uses to control the car. There are places to store the fuel and places to store the passengers and their goods. Physically, however, cars have changed greatly over a century: they are made of different materials, and they are faster, safer, and much more reliable and comfortable. There's a world of difference between my first car, a well-used 1959 Volkswagen Beetle, and a Ferrari, but either one will carry me and my groceries home from the store or across the country, and in that sense they are functionally the same. (For the record, I have never even sat in a Ferrari, let alone owned one, so I'm speculating about whether there's room for the groceries.)

The same is true of computers. Logically, today's computers are very similar to those of the 1950s, but the physical differences go far beyond the kinds of changes that have occurred with the automobile. Today's computers are much smaller, cheaper, faster and more reliable than those of 50 years ago, literally a million times better in some properties. Such improvements are the fundamental reason why computers are so pervasive.

The distinction between the functional behavior of something and its physical properties — the difference between what it does and how it's built or works inside — is an important idea. For computers, the "how it's built" part changes at an amazing rate, as does how fast it runs, but the "how it does what it does" part is quite stable. This distinction between an abstract description and a concrete implementation will come up repeatedly in what follows.

I sometimes do a survey in my class in the first lecture. How many have a PC? How many have a Mac? The ratio was fairly constant at 10 to 1 in favor of PCs in the first half of the 2000s, but changed rapidly over a few years, to the point where Macs now account for well over three quarters of the computers. This is not typical of the world at large, however, where PCs dominate by a wide margin.

Is the ratio unbalanced because one is superior to the other? If so, what changed so dramatically in such a short time? I ask my students which kind is better, and for objective criteria on which to base that opinion. What led you to your choice when you bought your computer?

Naturally, price is one answer. PCs tend to be cheaper, the result of fierce competition in a marketplace with many suppliers. A wider range of hardware add-ons, more software, and more expertise are all readily available. This is an example of what economists call a network effect: the more other people use something, the more useful it will be for you, roughly in proportion to how many others there are.

On the Mac side are perceived reliability, quality, esthetics, and a sense that "things just work," for which many consumers are willing to pay a premium.

The debate goes on, with neither side convincing the other, but it raises some good questions and helps to get people thinking about what is different between different kinds of computing devices and what is really the same.

There's an analogous debate about phones. Almost everyone has a "smart phone" that can run programs ("apps") downloaded from Apple's App Store or Google's Play Store. The phone serves as a browser, a mail system, a watch, a camera, a music and video player, a comparison shopping tool, and even occasionally a device for conversation. Typically about three quarters of the students have an iPhone from Apple; almost all the rest have an Android phone from one of many suppliers. A tiny fraction might have a Windows phone, and (rarely) someone admits to having only a "feature phone," which is defined as a phone that has no features beyond the ability to make phone calls. My sample is for the US and a comparatively affluent environment; in other parts of the world, Android phones would be much more common.

Again, people have good reasons — functional, economic, esthetic — for choosing one kind of phone over others but underneath, just as for PCs versus Macs, the hardware that does the computing is very similar. Let's look at why.

1.1 Logical Construction

If we were to draw an abstract picture of what's in a simple generic computer — its logical or functional architecture — it would look like the diagram in Figure 1.1 for both Mac and PC: a processor (the CPU), some primary memory (RAM), some secondary storage (a disk) and a variety of other components, all connected by a set of wires called a bus that transmits information between them.

If instead we drew this picture for a phone or tablet, it would be similar, though mouse, keyboard and display are combined into one component, the screen. There's certainly no CD or DVD, but there are hidden components like a compass, an accelerometer, and a GPS receiver...

Details zur Ausgabe

• Verlag: Princeton Univers. Press
• Erscheinungsdatum: 2017
• Sprache: Englisch
• ISBN 10: 069117654X
• ISBN 13: 9780691176543
• Einband: Gebundene Ausgabe
• Anzahl der Seiten: 256
• Kontakt zum Hersteller: Princeton University Press; https://press.princeton.edu/books; ; 7th Floor, New South Building; PRINCETON; NJ; 8544; USA
• Verantwortliche Person: Nicht verfügbar