Über die Autorin bzw. den Autor

PETER COOK and SCOTT MANNING are the Compududes(r), whose popular radio show is heard on National Public Radio. The 'Dudes have also written about computers for the Philadelphia Inquirer and Knight-Ridder Wire Services, and they have appeared on the Discovery Channel's Home Matters and Fox Network News.

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Why Doesn't my Floppy Disk Flop? And Other Kids' Computer Questions Answered by the Compududes.

For the best answers, coolest Web sites, and excellent cyber-activities, pick up Why Doesn't My Floppy Disk Flop? This lively, informative guide provides the answers to dozens of questions that you (and your parents!) really want to know. Combining their popular brand of humor with cartoon illustrations, sidebars, and tons of advice, the Compududes make all the learning seem like play. From the ins and outs of hardware and software to the best ways to take advantage of the Internet to the exciting future of computing, the answers and explanations in Why Doesn't My Floppy Disk Flop? are guaranteed to plug you in, log you on, and turn you into a computer whiz in no time!

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Why Doesn't My Floppy Disk Flop?

Jossey-Bass

Contents

Welcome to Our Book..............................................1Introduction: Highlights of Computer History.....................31. Hardware......................................................92. Software......................................................313. The Internet..................................................454. Good Computer Habits..........................................695. The Computer Future...........................................81Glossary.........................................................85Bibliography.....................................................88Index............................................................89

Chapter One

Everyone has a general idea of what a computer is, but not many really know what's going on inside that beige box on the desk. But don't worry, it's not as complicated as you may think.

From the largest computer that NASA uses to keep the space shuttle flying to the smallest computer chip inside your microwave oven, all computers do the same three basic things. First, they get information from the outside world. For the space shuttle, that information includes how fast it is going, how high it is, and so on. For the microwave oven, the information might relate to the kind of food you are putting in it. Next, computers do something with that information, like decide how much fuel to burn to move the shuttle, or how long to cook your popcorn. Once that is decided, they send out signals to make the engines burn or the microwaves bounce around in the oven.

The Basics

What are hardware and software?

* Hardware refers to all of the parts of the computer, from the computer box to the computer monitor to the printer. Software refers to all of the programs that go into your computer.

What are the basic parts of a computer?

* The monitor is the big screen that you look at. The computer box is what holds its guts-all the chips, circuit boards, and so on. The central processing unit (CPU), the chip that carries the basic instructions about how the computer works, is in this box, so people sometimes refer to the box as the CPU even though it contains much more than just the CPU. The box also includes one or more slots, or disk drives. The keyboard is what you use to type words and commands. The mouse is the little box with a rolling ball inside that you use to move the cursor around the screen.

What is a motherboard?

* If you look inside a computer, you will see a huge circuit board that fills one side of the case. Circuit boards, computer chips, and wires are all connected together on the motherboard, or the main circuit board, of the computer. The motherboard (there isn't a fatherboard) is where you find the basic circuits like the central processing unit and RAM memory chips. The parts like the sound card, the floppy disk drive, and the CD-ROM player are all connected and controlled by the motherboard.

What is a computer chip?

* A computer chip is a tiny group of millions of electronic components and circuits in your computer that make it work. These days computer chips are made of silicon and metals like tin, gold, and copper.

What's the point of making things in a computer so incredibly tiny?

* There are two reasons why circuits in computers are so tiny. First, if the parts were larger, and they could be, your desktop computer would be the size of your house and you couldn't have laptops or palmtops. The second reason is that the smaller you make computers, the faster they can go. By reducing the length of the wires and the distance between computer chips you actually speed up the computer.

Can you make a computer so small it can fit in your brain?

* Not yet, but in April 1998 two doctors from Emory University, Dr. Bakay and Dr. Kennedy, connected a human brain to an electronic device that amplifies brain signals. The signals are transmitted from an antenna connected to the device to a laptop computer. The patient, who is completely paralyzed, is able to move the computer cursor around a screen and communicate with the doctors.

What does "Intel Inside" mean?

* Intel is a company that makes computer chips for most of the computers sold in the last twenty years. The Pentium and the Pentium II are very powerful chips that contain your central processing unit or CPU.

Bits and Bytes

What's a computer bit?

* A computer bit is the smallest unit of data handled by a computer. It represents either 0 or 1. This is known as a binary number system. A computer actually works by using on and off switches. If a switch is off, it means 0; if it's on, it means 1. There are millions of microscopic switches within a computer's microchips.

How many bits does a computer use at once?

* Your computer works in 8-bit chunks called bytes. It also works with 16 bits at a time (called a word) or 32 bits at a time (called a long word). The number of bits that a computer works with depends on what you ask it to do. If you are working with letters, your computer is moving bytes at a time, because one byte can store one character (one letter, or space, or punctuation mark). If you are painting with an art program, your computer will usually work with long words, because 32 bits is enough data to record all of the colors that you can see.

Memory

What is memory?

* Memory in a computer is a lot like an address book that the computer uses to keep track of numbers and other information. For a program to run, the computer must load it into memory; then it starts following the instructions one at a time. If the program tells the computer to add two numbers and then multiply that answer by another number, the computer will first do the addition and then store the answer in memory and use it to multiply.

Computer memory is organized as a bunch of addresses, one per byte. The computer can read or write to any address in memory without going through every address before and after it. This is called random access.

What is the difference between RAM and ROM?

* The most important type of memory is usually called random access memory, or RAM. The name random access means that you can get to any storage location that you want in any order. Actually all computer memory is random access. The important thing about data stored in RAM is that it will hang around only while the power is on. If you turn the power off without saving your work somewhere else, you will lose any data that you have been working on.

The other type of memory that you will find in a computer is called read-only memory, or ROM. Like RAM, ROM is random access, but unlike RAM, anything stored in ROM is going to be stored in the computer chip forever. In addition, read-only means that you cannot change the data that is stored in ROM; you can only use it. The instructions that tell the computer how to start up and read the hard drive are stored in ROM.

How much memory do I really need?

* The amount of memory that you have in your computer is very important. When we talk about memory, we mean RAM, or random access memory. If you do not have enough, your computer may run very slowly, or it may not run some programs at all. Figuring out how much memory you need is not an exact science.

As of this writing, most computers have 32 megabytes of memory installed. Computers that people use to create professional three-dimensional graphics have 64 megabytes. The amount of memory that people need has been increasing constantly, and we can only say that sometime in the future you will probably need more RAM.

It's always a good idea to read the side of the box when you buy a new game or other software. All software boxes list how much RAM each program needs to run on a computer. Make sure your computer has enough memory left to run that program.

Disks, Drives, and Monitors

What are disks?

* Since RAM forgets everything that is stored when the power goes away, you need somewhere to put your data when you want to turn the computer off. The place where data is stored is called a disk. Disks can be floppy disks, hard drive disks, recordable CDs, or backup storage disks like Iomega Zip disks or Imation Super Disks. A floppy disk can hold 1.44 megabytes of information. Storage disks can hold 100 megabytes or more; recordable CDs can hold as much as 650 megabytes; and the disks in hard drives have several gigabytes of storage space.

Floppy disks, recordable CDs, and Iomega Zip disks are all portable. They can be inserted into a disk drive in your computer or attached to your computer to collect information, then given to someone to use on another computer. The hard drive uses a hard disk that stays inside your computer.

Floppy disks are the least expensive, but they are not good for permanently storing data. The thin, floppy plastic can wear out and lose data over many years.

Why doesn't my floppy disk flop?

* The 3 1/2-inch-wide "floppy" disk you have is covered by a hard plastic case. Inside the protective hard case is a thin piece of plastic that is actually floppy, or flexible. The first portable disks, in the early 1980s, were larger and were enclosed in floppy plastic cases. They could easily be damaged if they were accidentally bent. After people switched to hard plastic cases, the name "floppy" just stuck.

Is there any difference between a hard drive and a floppy drive?

* There is one big difference: speed. In a floppy drive the recording head actually touches the disk, but in a hard drive the head flies over the disk. So saving to your hard drive is faster than saving to a floppy disk. To give you a good idea of the speed of your hard drive and how fast the head flies over the hard drive disk, imagine a jet airplane flying along at about 600 miles per hour only 10 inches above the ground. The head of a hard drive flies over the hard drive platter that quickly.

Why does my computer make funny noises when I turn it on?

* When you turn your computer on, the hard drive has to start up. The first thing that it does is start spinning the platters inside. This is what makes the whining sound that you hear at first. The next thing that happens is a clicking sound as the hard drive moves the read/write heads back to the outer parts of the platter. These sounds are normal, and you should hear them the same way every time you start up your computer. If these sounds change, you may need to have a service person check things out to make sure that your hard drive is okay and not getting ready to break. You can't see any of this because the hard drive is sealed inside a case. The sealed case keeps out dirt and dust and protects the hard drive platters.

My hard drive is full. What can I do?

* There are three things you can do. First, start cleaning up. Get rid of all those old programs that you never use, clean up temporary files (files that programs use while they run, and are supposed to clean up afterwards, but don't always), and move things like old schoolwork to floppy disks and delete them from the hard drive. Just make sure you know what you are deleting from the hard drive and that you have your parents' permission. You don't want to end up deleting any important instructions to the system or your dad's manuscript!

Second, if you have Windows you can adjust the size of the Recycle Bin, which is located on your computer desktop. The Recycle Bin is where you toss files you want to delete from the computer's hard drive. Place your mouse cursor over the Recycle Bin, and click the right mouse button once. In the little window that appears, click on "Properties," and another window will pop up called "Recycle Bin Properties." In the middle of the window is a slider that selects the percentage size of your hard drive that is reserved for the Recycle Bin. When you buy a new PC, the slider is always set at 10%. This means that if you have a 6.4-gigabyte hard drive, 640 megabytes are set aside for the Recycle Bin. Reset the slider to 1%. You will free up a lot of megabytes this way. You can always change it back if you have to get rid of a huge file.

The third way to get more space is to buy a bigger hard drive. You can replace your small hard drive or even add a second hard drive to most computers. However, a new hard drive costs at least $200, and you would have to pay someone to install it.

What is my computer doing when I first turn it on?

* As the computer powers up, you will see information displayed on your monitor. On a PC, numbers and words will fly by. On a Mac, you will not see the numbers during the startup of the computer-you see words that say "Welcome to MacOS," referring to the Macintosh operating system. The computer will check the RAM as well as information about drives and whatever other things are in, or attached to, your computer. A memory chip in your computer called the BIOS (Basic Input/ Output System) chip stores all of this information. Once your computer has checked to make sure everything is working, it will display your desktop screen.

This process of starting up is called "booting up," and it comes from the old expression "pulling yourself up by your bootstraps."

Your computer has a lot of work to do before it is ready to do what you want it to. Once the computer is sure that all systems are going, it will look for instructions about what to do next. These instructions are usually part of the operating system, a software program that tells your computer how to organize information. The more advanced your operating system is, the longer it will take to start.

How does my monitor work?

* Your monitor's screen, like most TV screens, is actually a really big vacuum tube. A vacuum tube is a sealed glass container that has all of the air removed from it. In the back of the tube, which is also called a cathode ray tube, or CRT, is a device called an electron gun. This gun fires a stream of electrons at the inside of the front of the CRT. The inside of the glass is coated with special chemicals called phosphors, which glow when the electrons hit them. If you have anything that glows in the dark, it has phosphors in it.

But how does the computer control what the electron gun draws on the screen? It's done with magnets. One magnet moves the electron beam stream left and right, and a second magnet moves it up and down, sort of like an Etch-A-Sketch toy drawing screen. When the electrons hit a spot on the screen, the spot glows. That small spot is called a pixel. The computer screen can have as many as 1,024 pixels across and 768 pixels up and down. That's a total of 786,432 pixels covering the entire screen.

In a color monitor, instead of a single coating of phosphors, the inside of the screen is printed in a pattern of three phosphors, one each for red, green, and blue. Instead of one electron gun, there are three guns, one for each color. Using different combinations of these three primary colors, your monitor can display up to sixteen million colors.

What is a modem?

* A modem is a device that allows your computer to communicate with other computers through a telephone line. An internal modem fits into a special slot inside your computer. An external modem plugs into a socket on the back of your computer. A telephone wire is attached from the modem to a telephone jack. The modem changes your data into sounds to send it through the telephone wires, and then another modem on the other end changes the sounds back into data.

Accessories

How do I get to hear sound on my computer?

* Your computer may already have speakers and a sound card (hardware that sends sounds to the speakers), or you can have them added. The sound card connects to the motherboard inside your computer. The speakers connect to the sound card through a cable in the back of the computer.

I have three speakers attached to my computer-why?

* If you have three speakers and one of them looks like a big box, you have a great sound system. The big box is called a sub woofer-no, it doesn't bark like a dog. The sub woofer is designed to play the deep bass sounds of explosions, booms, and deep bass voices. The other two speakers send out the high- and middle-range sounds. When you set them up, put the sub woofer on the floor under your computer desk, and place the other two speakers to the left and right of the desk.

What is a CD-ROM drive?

* CD-ROM stands for compact disc-read-only memory. The computer CD drive works the same way as the compact disc player attached to your family stereo. Information in the form of sound, graphics, words, and video is stored on the disc-up to 650 megabytes!

The information is read off the disc in a unique way. If you looked at the bottom of the disc (the side without pictures or words) with a very powerful microscope, you would see little pits and scratches in the compact disc. Those pits are information. When the disc spins in the CD-ROM drive, a laser beam flashes on the pits and the computer reads the information off the disc. Be careful not to scratch the bottom of the disc, because that will make the laser beam skip over information.

(Continues...)

Excerpted from Why Doesn't My Floppy Disk Flop?by Peter Cook Scott Manning Copyright © 1999 by Peter Cook. Excerpted by permission.
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