Running MS DOS

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Running MS DOS, by Van Wolverton, pages 26-27

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When you test drive a car, you already know how to start it.  The

test drive is to help you become familiar with the controls, the

steering, the brakes, the overall "feel" of the car.  Now it's

time to take a test drive with DOS.  Your learned how to start

DOS in the last chapter.  It's time to begin learning how to

control DOS, how to "steer" it in the direction of one task of

another, and how to call a halt when you want or need to.

That's what this chapter is all about.  It introduces you to the

directory of files that DOS keeps on each disk, and shows you how

to use the specific keys on your keyboard.   You use these keys

to tell DOS to cancel lines or commands, freeze the display, and

restart DOS.

To try the examples given here, start up your computer, as you

did in the last chapter.  Enter the appropriate date and time, so

that DOS responds with the system prompt, A> (C> of you are using

a fixed disk).  Don't worry about leaving your computer on while

you read the text between examples; DOS is patient.

Note:  Part of this chapter deals with keys that have special

meaning for DOS.  If you are not using an IBM personal computer,

you may want to check your documentation for equivalent keys on

your system.

Recall from Chapter 1 that information stored on a disk is stored

as a file.  DOS automatically keeps and updates a list of every

file you save on every diskette you use.  This list is called

directory.  If you create and save a new file, DOS adds it to the

list.  If you revise and old file, DOS keeps track of that, too. 

The directory eliminates the need to keep a separate record of

everything you save on each diskette.  You can tell DOS you want

to see the directory whenever DOS is displaying the system

prompt.

The example on the next section serves the double purpose of

showing you a directory and showing you around the DOS system

disk itself.  As you use the system more, you will come to

recognize many of the DOS commands.  Before you look at a

directory, though, you should know a little about how DOS saves

your files.

Whenever you create a file, you give it a name, called the file

name, of up to eight characters.  Of you wish, you can add a

suffix, called the extension, of up to three more letters. 

(Chapter 4 and 5 present more on files).  

Whenever you ask DOS to show you the directory of a diskette, it

lists your files by name (and extension, if there is one).  It

also shows you the size of your file, in units called bytes, and

it gives you the date and the time file was either created or

last changed (that's why DOS prompts you for the date and time).

Note:  A byte is the amount of storage required to hold one

character in computer memory or on a disk.  Here are a few

familiar items and their sizes, in bytes: the letters abcd, 4

bytes (1 byte per letter); the words United States, 13 bytes

(blanks count); a double-spaced, typewritten page, 1500 bytes;

this book, 600,000 bytes (approximately).

Depending on which version of DOS you're using, and whether your

drives use one or both sides of a diskette, your diskettes hold

from 163,840 to 368,640 bytes.  For convenience, quantities the

large are usually given in kilobytes, or K.  One kilobyte equals

1024 bytes, so the capacity of your diskettes can range from 160K

360K.