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?
To appreciate the role MS-DOS plays, take a quick look at the pieces of your computer system and what they do.
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.
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.
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 anotherBeethoven's Fifth Symphony is put aside and replaced by Haydn's Surprise Symphony, for examplethe 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 anotherfor example, an accounting program is put aside and replaced with a word processorthe 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.
A hard disk holds much more information than a floppy diskfrom 15 to 100 times as much, or even moreand 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.
A disk fileusually called a fileis 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.
If your computer has a hard disk, MS-DOS is probably already on itplaced 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.
When a new version of MS-DOS appears, a change in the number following the decimal point6.0 to 6.2, or even 6.22, for examplemarks 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 onlyfor 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.
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 managera program that lets you search a file for specific informationusing 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.
The next chapter starts you off at the keyboard.