ProfitPress Mega CDROM2 …eeware (MSDOS)(1992)(Eng)/ProfitPress-MegaCDROM2.B6I/MAGAZINE/MISC/MNJAN91.ZIP/DOS01

Text File | 1990-11-02 | 10.3 KB | 238 lines

Copyright (c) ZEAK and Associates, 1990

This is the first of a two part article attempting to de-mystify DOS.




                               WHAT IS DOS?


You're the proud owner of a new computer and you've picked up one or two
programs like a word processor or a spreadsheet to use. But...what is this
thing called DOS?

Why do you hear so much about it, why have books been written about it, and
why have hundreds of pages of instructions been written for it?


                        DOS IS A PROGRAM (SOFTWARE)

DOS is a special sort of software.  Odds are that none of your other
software (programs) would work without it, because DOS controls every part
of your new computer system.

DOS not only makes it possible for your other programs to work, it also
gives you complete control over what your computer does.  DOS is the link,
the interface, between you and your computer.  To appreciate the role DOS
plays, let's take a quick look at the various pieces of your computer
system and what they do.


                        HARDWARE MAKES IT POSSIBLE

The computer equipment is called hardware.  It probably includes a
keyboard, display (monitor), printer, and one or more disk drives.

The purposes of the first three are pretty obvious:

    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 initially obvious, but it's
purpose becomes clear as you use the system:

    A disk drive records and plays back information.

Some types of IBM (and compatible) computers are listed a the end of this
article.

The computer's information is recorded in files on disks and you'll find
that disk files are as important to your computer work as paper files are
to the work you do in an office.


                 SOFTWARE - THE STUFF THAT MAKES IT HAPPEN

It doesn't matter if you have a basic system or the latest, high powered
80486-based computer on the market, it can't do anything without software.

There are two main kinds of software (programs):

    1.        System programs, which control the operation of the computer
              system.

    2.        Application programs, which perform more obviously useful
              tasks, such as word processing.

Each program 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 connection, change
the colors on a color display, and so on through all the capabilities of
the hardware.

All application programs have the same needs.  So 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 (word processor), tracking accounts receivable
(spreadsheet), or calculating stress in a bridge beam (scientific problem
solver).  DOS is an operating system.  The initials stand for Disk
Operating System.

                      DOS IS A DISK OPERATING SYSTEM

The operating system for many computers, including IBM personal computers
(and look-a-likes named clones), is the Disk Operating System. It is called
a disk operating system because much of its work involves managing disks
and disk files.

There are two popular versions of DOS marketed.  They are PC-DOS published
by IBM, Inc. and MS-DOS published by Microsoft, Inc.  They are the same in
most ways, but do vary in the features are made available and how they
operate.  Generally speaking, it's best to use PC-DOS on true IBM equipment
and MS-DOS on compata=ibles (clones).  Other companies publish versions of
DOS to be used specifically on their brands of equipment, but IBM and
Microsoft are the most well known.

An operating system plays a role something like a symphony conductor.  When
the score calls for the French horns to play, the conductor cues them.
When the score says the drums should play more softly the conductor
instructs the drummer.

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...Moon River is put aside to be replaced by Handel's Messiah, the
same musicians use the same instruments at the same conductor's directions.
The elements are all the same, but the outcome is different.

When an accounting program (score) is put aside and replaced with a data
base program (score), the same hardware (instuments) carries out the
instructions of the same operating system (conductor).  A different
program, different results.  DOS coordinates the computer system, just as
the conductor coordinates the orchestra.

Your application programs run while DOS keeps the system humming.  Much of
what DOS does, such as how files are stored on a disk or characters are
printed on the printer, is invisible to you.  You control the things you
care about, such as which program to run, what report to print, or what
files to erase.




                                DISK DRIVES

Personal computers use two types of disks.

    1.        A flexible disk in a protective plastic jacket, called a
              diskette, which you can remove from the drive, and

    2.        A permanently mounted platter called a hard disk.

There are two types of diskettes.  One is 5.25 inches square in a flexible
plastic jacket.  The other measures 3.5 inches square in a rigid plastic
shell.

A hard disk holds from 15 to 100 times as much as a floppy diskette (even
more) and it writes and retrieves information a lot faster than a floppy.
Most personal computers have either one hard disk and one diskette drive,
or two diskette drives.




                        DISK FILES...DATA CABINETS

Just as paper files organize and store most written office records,
computer information is organized and stored in disk files.  A disk file
(usually just called a file) is a collection of related information stored
on a disk.

A file could be a letter, an income tax return, or a list of customers.  It
could also be a program, because the programs (software) you use are stored
in files.  Files are involved with almost all computer work.


                    BUT WHY DIFFERENT VERSIONS OF DOS?

DOS has been revised a number of times since its initial release.  The
first version was numbered 1.00.  Each revision of DOS is capable of doing
more things than the one before it, or newer versions are released to fix
problems in the previous one.  Ways are found to take advantage of more
sophisticated hardware.  Each time you start up your system, DOS displays
the version number that you are using.  If you want to know what version of
DOS is installed on your machine, type "VER" on the command lind and press
the enter key.  DOS will display the version number.


When a new version of DOS appears, a change in the number following the
decimal point (3.20 to 3.30, for example) marks a minor change that leaves
DOS substantially the same as the previous version.  A change in the number
preceding the decimal point marks a major change.  Version 2.00, for
example, offered almost three times as many commands as version 1.10.

Even though newer versions may have much more capability, they remain
compatible with earlier versions.  This means that if you start with
version 2.1, you can still use all your knowledge and experience, plus all
your files and diskettes, when you move to a newer version.  All you'll
have to learn are the commands and features the new version has added.


          COMPATIBILITY - WHAT DOES IT MEAN, WHY DOES IT MATTER?

You may have seen the terms "DOS-compatible" or "IBM compatible" used in an
article or advertisement.  Just what does compatible mean?  Although some
technical issues are involved, the most meaningful measure of compatibility
is the extent to which you can use the diskettes from one system with
another.  If two systems are totally (100%) compatible, you can freely
exchange diskettes.  This situation is common among IBM-compatible
computers now, but was a severe problem in times past.

If two systems are incompatible, you cannot exchange diskettes because
neither system can read files stored by the other.  That's why you can't
use a diskette from an IBM Personal Computer in an Apple computer.  If two
systems are partially compatible, you can interchange some diskettes,
particularly those that contain files of information (data).  This last
level of partial compatibility is what is usually meant by the terms
"MS-DOS compatible" and is one of the advantages of using an operating
system that runs on so many different machines.


                        YOU CAN DO A LOT WITH DOS!

DOS coordinates the operation of the computer for your application
programs.  That's valuable, but DOS has much more to offer.  You can use
DOS, 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, DOS includes a program called Edlin that lets you create and
revise files of text.  Although it's not a word processor, Edlin is fine
for short memos and lists.  Using Edlin, you can write short documents in
less time than it might take to start your word-processing program and
store the file.








You can tailor DOS to your specific needs by creating powerful commands in
batch files made up of other DOS commands, and you can even create your own
small applications.  For example, you could create a simple file manager (a
program that lets you search a file for specific information) using nothing
but DOS commands.  Your knowledge of DOS can range from just enough to use
a single application program to mastery of the full range of capabilities
in the later versions.  But no matter how far you go, you don't have to
learn how to program.  You can do fine just using DOS.

Next month we'll put these things we've discussed into practice.  Also, we'll
offer a summary of the different types of IBM and compatible computers from
the venerable PC to the newest dream...the 80586.

Written by Eugene A. Zeak, Jr.