How a computer works book

How Computers Work: The Evolution of Technology

Название: How Computers Work: The Evolution of Technology
Автор: White R., Downs T.
Издательство: Que Publishing
Год: 2015
Страниц: 383
Формат: pdf
Размер: 183 mb
Качество: отличное
Язык: английский

How Computers Work is the definitive illustrated guide to the world of PCs and technology. In this new edition, you’ll find detailed information not just about PCs, but about how changes in technology have evolved the giant, expensive computer dinosaurs of last century into the smaller but more powerful smartphones, tablets, and wearable computing of today. Whether your interest is in business, gaming, digital photography, entertainment, communications, or security, you’ll learn how computing is evolving the way you live.
A full-color, illustrated adventure into the wonders of Technoloogy.

This full-color, fully illustrated guide to the world of technology assumes nothing and explains everything. Only the accomplished and award-winning team of writer Ron White and artist Tim Downs has the unique ability to meld descriptive text with one-of-a-kind visuals to fully explain how the electronic gear we depend on every day is made possible. In addition to all the content you’ve come to expect from prior editions, this newly revised edition includes all-new coverage of topics such as:
-How smartphones and tablet PCs put the power of a desktop computer in your hands–literally
-How computing technology is linking our homes, work place, entertainment, and daily communications
-How advances such as Facebook, Twitter, Google, eBay, and smartphones are expanding our universe of friends, knowledge, and opportunity
-How increased miniaturization leads to new products, such as smartphone, smartwatches, and Google Glass
-How computing technology takes advantages of quantum physics and innovations no one even imagined a few years ago
For two decades, How Computers Work has helped newbies understand new technology, while hackers and IT pros have treasured it for the depth of knowledge it contains. This is the perfect book about computing to capture your imagination, delight your eyes, and expand your mind, no matter what your technical level!
Beautifully detailed illustrations and jargon-free explanations walk you through the technology that is shaping our lives. See the hidden workings inside computers, smartphones, tablets, Google Glass, and the latest tech inventions.

How Computers Work

Processor and Main Memory

Roger Young

Copyright 2001, 2002, 2009 by Roger Young.
All rights reserved.

This is a tutorial web book. All 152 pages of the large paperback book with 96 diagrams are on 38 web pages here.

Even if you know nothing about electronics, you have come to the right place.

If you are wondering how microprocessors work, you have come to the right place. A microprocessor is a small processor.

If you already know something about electronics, don’t be put off by the fact that the book starts out very simple and uses relays instead of transistors. You will get through the first chapter quickly. See web page 24, below, for just how complex it gets.

If you have a very fast connection (DSL or cable modem), then you can click the following link to see an easier to read (PDF) version of the book. It is 783 kilobytes, so it will take a while.

With a regular (56K) modem, it will take about 3 or 4 minutes to be displayed.

The pdf does not include the addendum on the ‘registers on bus’ computer architecture.

If you print this book (‘How Computers Work: Processor and Main Memory’) out, it will be easier to follow when it gets to large, relatively-complex diagrams.

Please email questions or comments to me (Roger Young) at:

thinkorrr@gmail.com

This book has been used as a supplementary text in 300 level computer science courses.

Last updated: January 2, 2018

This page can be reached indirectly by going to the easy-to-remember URL howcomputers.com in case you want to tell anyone about it.

Introduction

Computers are the most complex machines that have ever been created. Very few people really know how they work. This book will tell you how they work and no technical knowledge is required. It explains the operation of a simple, but fully functional, computer in complete detail. The simple computer described consists mainly of a processor and main memory. Relays, which are explained, are used in the circuitry instead of transistors for simplicity. This book does not cover peripherals like modems, mice, disk drives, or monitors.

Did you ever wonder what a bit, a pixel, a latch, a word (of memory), a data bus, an address bus, a memory, a register, a processor, a timing diagram, a clock (of a processor), an instruction, or machine code is? Though most explanations of how computers work are a lot of analogies or require a background in electrical engineering, this book will tell you precisely what each of them is and how each of them works without requiring any previous knowledge of computers or electronics. However, this book starts out very easy and gets harder as it goes along. You must read the book starting at the first page and not skip around because later topics depend on understanding earlier topics. How far you can get may depend on your background. A junior high school science background should be enough. There is no mathematics required other than simple addition and multiplication. This is a short book, but it must be studied carefully. This means that you will have to read some parts more than once to understand them. Get as far as you can. You will be much more knowledgeable about how computers work when you are done than when you started, even if you are not able to get through the whole text. This is a technical book though it is aimed at a non-technical audience. Though this book takes considerable effort to understand, it is very easy for what it explains. After you have studied this book, if you go back and read it, it will seem simple. Good Luck!

Computers

I t was probably the worst prediction in history. Back in the 1940s, Thomas Watson, boss of the giant IBM Corporation, reputedly forecast that the world would need no more than «about five computers.» Six decades later and the global population of computers has now risen to something like one billion machines!

To be fair to Watson, computers have changed enormously in that time. In the 1940s, they were giant scientific and military behemoths commissioned by the government at a cost of millions of dollars apiece; today, most computers are not even recognizable as such: they are embedded in everything from microwave ovens to cellphones and digital radios. What makes computers flexible enough to work in all these different appliances? How come they are so phenomenally useful? And how exactly do they work? Let’s take a closer look!

Photo: NASA runs some of the world’s most powerful computers—but they’re just super-scaled up versions of the one you’re using right now. Photo by Tom Tschida courtesy of NASA.

Contents

What is a computer?

Photo: Computers that used to take up a huge room now fit comfortably on your finger!.

Imagine if a computer were a person. Suppose you have a friend who’s really good at math. She is so good that everyone she knows posts their math problems to her. Each morning, she goes to her letterbox and finds a pile of new math problems waiting for her attention. She piles them up on her desk until she gets around to looking at them. Each afternoon, she takes a letter off the top of the pile, studies the problem, works out the solution, and scribbles the answer on the back. She puts this in an envelope addressed to the person who sent her the original problem and sticks it in her out tray, ready to post. Then she moves to the next letter in the pile. You can see that your friend is working just like a computer. Her letterbox is her input; the pile on her desk is her memory; her brain is the processor that works out the solutions to the problems; and the out tray on her desk is her output.

Once you understand that computers are about input, memory, processing, and output, all the junk on your desk makes a lot more sense:

Artwork: A computer works by combining input, storage, processing, and output. All the main parts of a computer system are involved in one of these four processes.

What is a computer program?

As you can read in our long article on computer history, the first computers were gigantic calculating machines and all they ever really did was «crunch numbers»: solve lengthy, difficult, or tedious mathematical problems. Today, computers work on a much wider variety of problems—but they are all still, essentially, calculations. Everything a computer does, from helping you to edit a photograph you’ve taken with a digital camera to displaying a web page, involves manipulating numbers in one way or another.

Photo: Calculators and computers are very similar, because both work by processing numbers. However, a calculator simply figures out the results of calculations; and that’s all it ever does. A computer stores complex sets of instructions called programs and uses them to do much more interesting things.

Suppose you’re looking at a digital photo you just taken in a paint or photo-editing program and you decide you want a mirror image of it (in other words, flip it from left to right). You probably know that the photo is made up of millions of individual pixels (colored squares) arranged in a grid pattern. The computer stores each pixel as a number, so taking a digital photo is really like an instant, orderly exercise in painting by numbers! To flip a digital photo, the computer simply reverses the sequence of numbers so they run from right to left instead of left to right. Or suppose you want to make the photograph brighter. All you have to do is slide the little «brightness» icon. The computer then works through all the pixels, increasing the brightness value for each one by, say, 10 percent to make the entire image brighter. So, once again, the problem boils down to numbers and calculations.

What makes a computer different from a calculator is that it can work all by itself. You just give it your instructions (called a program ) and off it goes, performing a long and complex series of operations all by itself. Back in the 1970s and 1980s, if you wanted a home computer to do almost anything at all, you had to write your own little program to do it. For example, before you could write a letter on a computer, you had to write a program that would read the letters you typed on the keyboard, store them in the memory, and display them on the screen. Writing the program usually took more time than doing whatever it was that you had originally wanted to do (writing the letter). Pretty soon, people started selling programs like word processors to save you the need to write programs yourself.

Today, most computer users rely on prewritten programs like Microsoft Word and Excel or download apps for their tablets and smartphones without caring much how they got there. (Apps, if you ever wondered, are just very neatly packaged computer programs.) Hardly anyone writes programs any more, which is a shame, because it’s great fun and a really useful skill. Most people see their computers as tools that help them do jobs, rather than complex electronic machines they have to pre-program. Some would say that’s just as well, because most of us have better things to do than computer programming. Then again, if we all rely on computer programs and apps, someone has to write them, and those skills need to survive. Thankfully, there’s been a recent resurgence of interest in computer programming. «Coding» (an informal name for programming, since programs are sometimes referred to as «code») is being taught in schools again with the help of easy-to-use programming languages like Scratch. There’s a growing hobbyist movement, linked to build-it yourself gadgets like the Raspberry Pi and Arduino. And Code Clubs, where volunteers teach kids programming, are springing up all over the world.

Photo: Is this a computer. or not? Chess-playing machines like this were popular in the 1970s. They worked exactly like computers using stored programs. But you couldn’t change the program in any way or get these machines do anything other than play chess, so they weren’t really examples of the kind of reprogrammable, general problem-solving machines that we mean when we’re talking about «computers.» By contrast, you can turn more or less any off-the-shelf modern computer (or smartphone) into a chess-playing computer just by loading a chess program or app. Photo by Marion S. Trikosko, US News & World Report Magazine Collection, courtesy of US Library of Congress.

What’s the difference between hardware and software?

What is an operating system?

Suppose you’re back in the late 1970s, before off-the-shelf computer programs have really been invented. You want to program your computer to work as a word processor so you can bash out your first novel—which is relatively easy but will take you a few days of work. A few weeks later, you tire of writing things and decide to reprogram your machine so it’ll play chess. Later still, you decide to program it to store your photo collection. Every one of these programs does different things, but they also do quite a lot of similar things too. For example, they all need to be able to read the keys pressed down on the keyboard, store things in memory and retrieve them, and display characters (or pictures) on the screen. If you were writing lots of different programs, you’d find yourself writing the same bits of programming to do these same basic operations every time. That’s a bit of a programming chore, so why not simply collect together all the bits of program that do these basic functions and reuse them each time?

Photo: Typical computer architecture: You can think of a computer as a series of layers, with the hardware at the bottom, the BIOS connecting the hardware to the operating system, and the applications you actually use (such as word processors, Web browsers, and so on) running on top of that. Each of these layers is relatively independent so, for example, the same Windows operating system might run on laptops running a different BIOS, while a computer running Windows (or another operating system) can run any number of different applications.

Operating systems have another big benefit. Back in the 1970s (and early 1980s), virtually all computers were maddeningly different. They all ran in their own, idiosyncratic ways with fairly unique hardware (different processor chips, memory addresses, screen sizes and all the rest). Programs written for one machine (such as an Apple) usually wouldn’t run on any other machine (such as an IBM) without quite extensive conversion. That was a big problem for programmers because it meant they had to rewrite all their programs each time they wanted to run them on different machines. How did operating systems help? If you have a standard operating system and you tweak it so it will work on any machine, all you have to do is write applications that work on the operating system. Then any application will work on any machine. The operating system that definitively made this breakthrough was, of course, Microsoft Windows, spawned by Bill Gates. (It’s important to note that there were earlier operating systems too. You can read more of that story in our article on the history of computers.)

What’s inside your PC?

Warning! Don’t open up your PC unless you really know what you’re doing. There are dangerous voltages inside, especially near the power supply unit, and some components can remain live for quite a time after the power has been turned off.

Photo: Inside the case of a typical PC showing four key areas of components, described below. Photo by ArmadniGeneral courtesy of Wikimedia Commons, published under a Creative Commons License.

It all looks pretty scary and confusing inside a typical PC: circuit boards like little «cities» with the chips for buildings, rainbow tangles of wires running between them, and goodness knows what else. But work through the components slowly and logically and it all starts to make sense. Most of what you can see divides into four broad areas, which I’ve outlined in green, blue, red, and orange on this photo.

Power supply (green)

Based on a transformer, this converts your domestic or office power voltage (say 230/120 volts AC) into the much lower DC voltage that electronic components need (a typical hard drive might need just 5–12V). There’s usually a large cooling fan on the outside of the computer case near the power socket (or a much smaller fan on a laptop, usually on one side). In this machine, there are two external fans (colored green and blue) just to the left, cooling both the power supply and the mainboard.

Mainboard (blue)

As its name suggests, this is the brain of a computer—where the real work gets done. The main processor (central processing unit) is easy to spot because there’s typically a large fan sitting right on top of it to cool it down. In this photo, the processor is directly underneath the black fan with the red central spindle. Exactly what’s on the mainboard varies from machine to machine. As well as the processor, there’s the BIOS, memory chips, expansion slots for extra memory, flexible ribbon connections to the other circuit boards, IDE (Integrated Drive Electronics) connections to the hard drives and CD/DVD drives, and serial or parallel connections to things like the USB ports, and other ports on the computer case (often soldered onto the mainboard, especially in a laptop).

Other circuit boards (red)

Although the mainboard can (theoretically) contain all the chips a computer needs, it’s quite common for PCs to have three other separate circuit boards: one to manage networking, one to process graphics, and one to deal with sound.

Drives (orange)

PCs typically have one, two, or three hard drives plus a CD/DVD reader/writer. Although some machines have only one hard drive and a single combined CD/DVD drive, most have a couple of empty expansion slots for extra drives.

PC makers tend to design and build their own motherboards, but most of the components they use are off-the-shelf and modular. So, for example, your Lenovo PC or Asus laptop might have a Toshiba hard drive, an Nvidia graphics card, a Realtek sound card, and so on. Even on the motherboard, the components may be modular and plug-and-play: «Intel Inside» means you’ve got an Intel processor sitting under the fan. All this means it’s very easy to replace or upgrade the parts of a PC either when they wear out or grow obsolete; you don’t have to throw the whole machine out. If you’re interested in tinkering, there are a couple of good books listed in the «How computers work» section below that will walk you through the process.

External connectors («ports»)

Photo: USB ports on computers are very robust, but they do break from time to time, especially after years of use. If you have a laptop with a PCMCIA slot, you can simply slide in a USB adapter card like this to create two brand new USB ports (or to add two more ports if you’re running short).

Apart from making it easy to swap data, USB also provides power to things like external hard drives. The two outer pins of a USB plug are +5 volt and ground power connectors, while the inner pins carry the data. When you plug your phone into a USB port on a bus or a train, you’re just using the outer pins to charge the battery.

USB gives you much more connectivity than old-fashioned serial computer ports. It’s designed so you can connect it in many different ways, either with one peripheral plugged into each of your USB sockets or using USB hubs (where one USB plug gives you access to a whole series of USB sockets, which can themselves have more hubs and sockets plugged into them). In theory, you can have 127 different USB devices attached to one computer.

How Computers Work

Computers are marvels of engineering, yet very few actually know how they work (this holds true among a lot of software developers). This will help augment [How the Computer Works][andrea-laue] by Andrea Laueu.

Transistors

You may remember in Elementry School building a transistor radio, or if you’re an audiophile, you may use transistors in a special sound system. A transistor is a semiconductor device with magical (well, it can seem that way) properties. They are capable fo amplifiying and switching electronic signals as well as amplifiying electronic power. These properties were discovered in the late 1940s, and today are the basis for every electronic device.

What is a transistor?

Semiconductor devices allow us to amplify and switch electronic signals. Different materials with unique physical properties that make this possible. For example, your car stereo, headsets, TV sets, etc., all use amplification transitors to reproduce sound. With computers, we use transistors that “switch” (on and off) to “do stuff” very quickly. Since a transitor doesn’t have mechanical movement (no magents, springs, etc), you can pack transistors together very tightly.

While the first transistors were quite large, they quickly shrank in size. In fact, the current generation of computer processors contain around 1.4 billion transistors.High-end servers can have up to 5.4 billion transistors per chip. This image of an the chip that runs an iPhone (the A7 ARM chip) contains about 1 billion transistors that are each about 22 nm large.

Processors

The “brain” of a computer is what is called the Central Processing Unit (CPU). This is where all the transistors are contained that can turn on-and-off, and controls your computer.

What Does a Computer Do?

A computer only does four things:

Logical Operations

This is the most basic thing a computer can do:

In electrical engineering, these are referred to as logic gates which allow one or more inputs to produce a single logical output (true or false). By connecting a series of transistor states (on/off) through relays, we can represent these logical operations.

Propogation Delay

Logical operations don’t happen instantly.

A value is called ‘stable’ when its the final, correct value (there’s aleays output, but not always stable) Each transistor has a delay where it responds to its inputs, which is relative to the physical characteristics of the transistor (size, materials, voltage, etc.) Overall delay is the delay of the longest-path (the longest chain of transistors) An output is stable after the inputs have been stable for at leat the gate delay.

How computers do math

How a computer works book

This book starts out very simple and gets more complex as it goes along, but everything is explained. The processor and memory are mainly covered. It explains in great detail the operation of a simple but functional computer.

This book presents a visual expert system for diagnosing component failure and identifying conflicts. The seventeen diagnostic flowcharts at the core of this book are intended for the intermediate to advanced hobbyist, or the beginning technician.

This guide is written in easy language and contains a lot of illustrations. The author would like to give you enough insight into and confidence about your PC’s workings that you would dare to upgrade your PC, or build your next PC yourself.

The purpose of the book is to take a basic computer system and show you how every part works. It is taught from a technicians point of view, not an engineer’s. It covers electronic components, logic circuits, CPU, computer system, assembly language, etc.

The book is designed for using the computer arithmetic of geometrical figures in their own research and development in the field of specialized processors. It covers both the affine transformations and the figures coding theory

Using everyday objects and familiar language systems such as Braille and Morse code, the author weaves an illuminating narrative for anyone who’s ever wondered about the secret inner life of computers and other smart machines.

Building a computer can be a very rewarding experience. Since you’re reading this, you’re probably thinking about building your next computer instead of buying one pre-built. Beginning from picking the parts, structuring, and so on to turn into an ideal PC.

This book is for people who would like to understand how computers work, without having to learn a lot of technical details. Only the most important things about computers are covered. There is no math except some simple arithmetic.

The purpose of this book is to give the reader a better understanding of how computers really work at a lower level than in programming languages like Pascal. It has extensive coverage of interfacing assembly and C code.

If you are interested in computers, their function and operation, but are discouraged by their complexity, you should read this book. It deals as simply as possible with the principles, and the combination of carefully written text and instructive illustrations should give older students a good basic knowledge of what computers are all about.

This book is the only book that is written for both novice and more experienced computer users. It provides easy to follow computer speedup and maintenance instructions written in plain English.

This desktop encyclopedia contains more than 10,000 terms, which are explained accurately and lucidly. There 800 illustrations that are used to show devices and clarify concepts.

Measure the world, record the data and display it graphically. The book is written to help those who want to get started interfacing computers with the physical world and turning recorded information into visual data.

This book is primarily oriented toward system programmers and computer security experts. In addition, electronic engineers, pc technicians and computer enthusiasts can also benefit a lot from this book.

It’s the one book that covers everything today’s beginners and near-beginners need to know: not just about Windows, but also about software, hardware, and the Internet.

Complete with helpful hints on how to avoid beginner mistakes, a list of extras and accessories you may want for your PC, and insider tips from a PC guru. Every programmer needs to understand the hardware they’re programming and how PC hardware and software interact.

This book will help you troubleshoot your laptop problem and take the most cost effective approach to repairing it, getting it repaired, or replacing it. It includes twelve full page troubleshooting flowcharts for laptop hardware troubleshooting and explanatory text for every decision point.

This practical guide to designing electronic circuits using small computers and programmable calculators makes it easy to implement both classical and sophisticated design techniques.

This part will break the computer down into its different components focusing on the Chassis, Power Supply and Motherboard. It will describe each component and function, explain the different specifications to look out for and provide a bit of history, too.

This part will break the computer down into its different components focusing on the CPU, RAM, Storage, Video Card and Expansions.

This book is a proven, step by step, illustrated manual, that will show how to easily and quickly speed up a computer and improve performance and reliability.

This book offers a realistic picture of making it on your own. Bestselling author, Morris Rosenthal, has 15 years of experience in the computer business, building and repairing thousands of PCs and helping hundreds of customers.

This book will take you through all of the steps to create a powerful computer system. It contains over 120 photographs to guide you through the process.

This book tells the history of the origins of Artificial Intelligence (AI). As the field that seeks to do things that would be considered intelligent if a human being did them, AI is a constant of human thought.

This book tells the story of the development, during the 1960s and 1970s, of AI, the field that sought to get computers to do things that would be considered intelligent if a person did them. Watching advances of the 1960s and 1970s by the efforts of AI founders.

This document discusses operating systems that Apple has created in the past, and many that it tried to create. Through this discussion, we will come across several technologies the confluence of which eventually led to Mac OS X.

With the complete amateur in mind who has no tech knowledge whatsoever, this guide will show you how to build your own PC! It is so easy to follow, even your technophobe grandmother could do it.

This handbook is designed to help you find ways to maintain your Windows PC and ensure it remains clean and speedy throughout its life.

The guide covers three major categories: (1) Upgrading your system, (2) Tuning up/speeding up your PC, (3) Emergency troubleshooting

Defensive Computing Techniques to Help You Avoid Malware and Data Loss. This handbook is designed to help you find ways to protect your Windows XP/Vista/7 PC and ensure your data is safe.

This book describes RAND1s contributions to the evolution of computer science, particularly during the first decades following World War II, etc..

This book is one of the most hardcore computer programming books out there. Starting with the fundamentals, it describes the most advanced features of the most advanced language: Common Lisp.

This book explains what HPC is and shows how it can help you or others within your company.

This guide will focus specifically on home networking. Setting up a network that will be used by a small number of computers and other devices, all of which are owned by people living in a single home.

In this guide you’ll find everything you need to know about the Raspberry Pi computer, its background, purpose, system specs, the software it runs and the amazing things it is capable of.

This book has been designed as a complete self-contained text for learning programming, using the Z80. It aims at providing a true level of competence to the person who wishes to program using this microprocessor.