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Running MS-DOS® 20th Anniversary Edition
Author Van Wolverton
Pages 640
Disk N/A
Level All Levels
Published 07/17/2002
ISBN 9780735618121
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Chapter 1: What Is MS-DOS?

1   What Is MS-DOS?

You've got your computer, and you've probably got one or two programs, such as a word processor or a spreadsheet, to use with it. But what is this thing called MS-DOS? Why do you hear so much about it, and why have hundreds of pages of instructions been written for it?

MS-DOS Is a Program

MS-DOS is a program, but it's not just any program. Chances are none of your other programs would work without it because MS-DOS controls every part of the computer system. MS-DOS not only makes it possible for your other programs to work, it also gives you complete control over what your computer does, and how MS-DOS is the link between you and your computer.

To appreciate the role MS-DOS plays, take a quick look at the pieces of your computer system and what they do.

Hardware Makes It Possible

Your computer equipment, called hardware, probably includes a keyboard, display, printer, and one or more disk drives. The purposes of the first three are straightforward: You type instructions at the keyboard, and the system responds by displaying or printing messages and results.

The purpose of a disk drive isn't quite so obvious, but it quickly becomes apparent as you use the system: A disk drive records and plays back information, much as a tape deck records and plays back music. The computer's information is recorded in files on disks; you'll find that disk files are as central to your computer work as paper files are to more traditional office work.

Software Makes It Happen

No matter how powerful the hardware, a computer can't do anything without programs, called software. Computers use two major types of software: system programs, which control the operation of the computer system, and application programs, which perform more obviously useful tasks, such as word processing.

Each program uses the hardware. It must be able to receive instructions from the keyboard, display and print results, read and write files from and to a disk, send and receive data through the computer's communications connections, change the colors on a color display, and so on, through all the capabilities of the hardware.

So that each program doesn't have to perform all these functions for itself, a system program called the operating system manages the hardware. The operating system allows an application program to concentrate on what it does best, whether it's moving paragraphs about, tracking accounts receivable, or calculating stress in a bridge beam. MS-DOS is an operating system.

MS-DOS Is a Disk Operating System

The most frequently used operating system for IBM and IBM-compatible computers is the Microsoft Disk Operating System—MS-DOS. MS-DOS is called a disk operating system because much of its work involves managing disks and disk files.

What Does an Operating System Do?

An operating system plays a role something like a symphony conductor's. When the score calls for the violins to play, the conductor cues the violins; when the score says the cellos should play more softly, the tympani should stop, or the entire orchestra should pick up the tempo, the conductor so instructs the musicians.

The players in the orchestra and their instruments represent the hardware. The experience and skill of the conductor represent the operating system. The score represents an application program.

When one score is replaced by another—Beethoven's Fifth Symphony is put aside and replaced by Haydn's Surprise Symphony, for example—the same musicians use the same instruments, and the same conductor uses the same experience and skills. A different sound, a different mood, perhaps, but the elements are the same.

When one application program is replaced by another—for example, an accounting program is put aside and replaced with a word processor—the same hardware carries out the instructions of the same operating system. A different program, a different purpose, perhaps, but the elements are the same.

MS-DOS coordinates the computer system, just as the conductor coordinates the orchestra. Your application programs run in concert with MS-DOS, trusting it to keep the system humming.

Much of what MS-DOS does, such as how it stores a file on a disk or prints on the printer, is invisible to you. But MS-DOS lets you control the things you care about, such as which program to run, what document to print, or what files to erase. These functions share an important characteristic: They need disks and disk drives.

Disk Drives

Personal computers use two main types of disk: a flexible disk in a protective plastic jacket, called a floppy disk, which you can remove from the drive, and a permanently mounted unit called a hard disk. There are two types of floppy disks: 5.25 inches square in a flexible plastic jacket, and 3.5 inches square in a rigid plastic shell.

A hard disk holds much more information than a floppy disk—from 15 to 100 times as much, or even more—and is much faster. Most personal computers have one hard disk and one or two floppy disk drives. Machines without a hard disk usually have two floppy disk drives.

To distinguish among the types of disks, this book uses floppy disk to mean either type of flexible disk, hard disk to mean only a permanently mounted disk, and disk to refer to both.

Disk Files

Just as you organize and store your written records in paper files, you organize and store computer information in disk files.

A disk file—usually called a file—is a collection of related information stored on a disk. It could be a letter, an income tax return, or a list of customers. It could also be a program, because the programs you use are stored in files.

Virtually all your computer work revolves around files. Because one of the major functions of MS-DOS is to take care of files, much of this book is devoted to showing you how to create, print, copy, organize, and otherwise manage files.

Where Is MS-DOS?

When your computer is turned off, MS-DOS is stored on disk. Although it's a special type of program, MS-DOS is still a program, and that means it's stored on disk in a set of files like any other collection of computer information.

If your computer has a hard disk, MS-DOS is probably already on it—placed there, perhaps, by your computer dealer, or by someone else who set up your system. If your computer does not have a hard disk, it must use MS-DOS from floppy disks, so it should have come with a copy of MS-DOS on two or more floppy disks.

Different Versions of MS-DOS

MS-DOS has been revised a number of times since its release in 1981; the first version was numbered 1.00. MS-DOS is revised to add more capability, to take advantage of more sophisticated hardware, and to correct errors. When you start up your system, MS-DOS may display the version number you are using.

When a new version of MS-DOS appears, a change in the number following the decimal point—6.0 to 6.2, or even 6.22, for example—marks a minor change that leaves the new version of MS-DOS substantially the same as the previous version. A change in the number preceding the decimal point marks a major change. Version 6.0, for example, adds several new features that weren't available in version 5.0.

Even though newer versions of MS-DOS can do a lot more than earlier versions of MS-DOS, they remain compatible with the earlier versions. Thus, if you start with version 2.1, you can still use all your knowledge and experience, plus your files and disks, when you move to a newer version of MS-DOS.

For simplicity, this book usually refers to MS-DOS by major version number only—for example, version 5 or version 4, rather than version 5.0 or version 4.01. It also omits references to versions of MS-DOS earlier than version 3, but much of the information applies to these versions too. Remember, version 2 is just as much a part of MS-DOS as version 5. It's simply older and, although it includes many of the features described here, it doesn't provide them all.

What Is Compatibility?

You've no doubt seen the term IBM-compatible in an article or an advertisement. What does compatibility actually mean? Compatibility essentially refers to the ability of one computer to use programs and data created for or stored on another computer. In everyday use, the most meaningful measure of compatibility is the extent to which you can use the same programs, data, and floppy disks in computers of different makes or different models:

  • If two systems are totally compatible, they can freely use the same programs and floppy disks. This is the type of compatibility exhibited among different models of IBM Personal Computers and the IBM-compatible machines made by manufacturers other than IBM. On these machines, such full compatibility is made possible in part by MS-DOS: Any computer that can run MS-DOS can run programs designed for MS-DOS, and that computer can (given the proper application programs) freely use floppy disks from any other MS-DOS computer.
  • Incompatible systems might use different versions of the same program, but they can't use either programs or floppy disks intended for the other computer. This is typically the situation between IBM and Macintosh computers. An IBM machine can, for example, use the IBM version of Microsoft Word, and the Macintosh can use the Macintosh version of Microsoft Word, but neither computer can use the version intended for the other.

What Can You Do with MS-DOS?

MS-DOS coordinates the operation of the computer for your application programs. That's valuable—essential, really—but MS-DOS has much more to offer. You can use MS-DOS itself, controlling it with instructions called commands, to manage your files, control the work flow, and perform useful tasks that might otherwise require additional software.

For example, MS-DOS includes a program that lets you create and revise files of text. Although it's not a word processor, the MS-DOS Editor is fine for short memos and lists. Using it, you can write short documents in less time than it might take using your word processing program.

You can tailor MS-DOS to your specific needs by creating powerful commands made up of other MS-DOS commands, and you can even create your own small applications. For example, this book shows you how to create a simple file manager—a program that lets you search a file for specific information—using nothing but MS-DOS commands.

MS-DOS versions 4 through 6 also include a separate program, called the Shell, that lets you choose commands and files from on-screen lists called menus. If you want, you can use the Shell for routine work, dispense with it and work directly with MS-DOS, or move freely between MS-DOS and the Shell as your work requires. Your knowledge of MS-DOS can range from just enough to use a single application program to mastery of the full range of capabilities in the latest version. But no matter how far you go, you needn't learn to program. It's all MS-DOS, and it's all in this book.

Chapter Summary

This quick tour of MS-DOS may have introduced several new terms and concepts. Here are the key points to remember:

  • A working computer system needs both hardware (equipment) and software (programs).
  • MS-DOS (the Microsoft Disk Operating System) coordinates the operation of all parts of the computer system.
  • A file is a collection of related information stored on a disk. Most of your computer work will involve files.
  • Besides running your application programs, MS-DOS is valuable in its own right.

The next chapter starts you off at the keyboard.

Last Updated: August 7, 2002
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