DRVSPACE.TXT

Welcome to Microsoft(R) MS-DOS(R), the most widely used operating system
for personal computers. This version of MS-DOS includes many new features
that turn your computer into a powerful tool for business or personal use. 

This file, the Microsoft MS-DOS User's Guide Addendum, briefly describes 
features new to MS-DOS 6.22 and explains how to use Microsoft DriveSpace 
integrated compression. 

If this version of MS-DOS is not yet set up on your computer, see the
chapter "Getting Started" in the Microsoft MS-DOS User's Guide for
information about how to use the Setup program. 


Table of Contents
-----------------
New Features of MS-DOS 6.22
Freeing Disk Space by Using DriveSpace
Getting Help
Setting Up DriveSpace
Using Express Setup
Using Custom Setup
If you chose to compress an existing drive
If you chose to create a new compressed drive
Understanding Disk Compression
Compressed Volume Files and Host Drives
How DriveSpace Calculates Free Space on a Compressed Drive
Using DriveSpace to Manage Compressed Drives
Compressing Additional Drives
Compressing an Existing Drive
Creating a New Compressed Drive
Using DriveSpace with Floppy Disks
Compressing a Floppy Disk
Using a Compressed Floppy Disk
Using Compressed Floppy Disks Without Automounting
Getting Information About Compressed Drives
Understanding DriveSpace and Memory
Getting More Information About DriveSpace
Troubleshooting DriveSpace


New Features of MS-DOS 6.22
=======================

MS-DOS 6.22 includes Microsoft DriveSpace, integrated disk compression 
that increases your available disk space by compressing files. DriveSpace 
appears similar to DoubleSpace, which was included with some earlier
versions of MS-DOS; however, DriveSpace stores compressed information in a
different format. For more information about DriveSpace, see the following
section. (If you are currently using DoubleSpace, type HELP DBLSPACE at the
MS-DOS command prompt for information about using DoubleSpace with MS-DOS
6.22.)

MS-DOS 6.22 DriveSpace also includes several new safety and convenience 
features that were not in MS-DOS 6 DoubleSpace. For more information, type 
HELP WHATSNEW at the MS-DOS command prompt, and then press ENTER.
For information about other new features of MS-DOS, see the "Welcome" 
chapter of the the Microsoft MS-DOS User's Guide or type HELP WHATSNEW
at the MS-DOS command prompt, and then press ENTER.

Freeing Disk Space by Using DriveSpace
==============================

DriveSpace frees space on hard and floppy disks by compressing the data
that is on them. DriveSpace is easy to set up and use. For instructions on
settingup DriveSpace, see "Setting Up DriveSpace" later in this file. After
you set up DriveSpace, your disk will have 50 to 100 percent more free
space. 

After you set up DriveSpace, you can maintain your compressed drives by
using the full-screen DriveSpace maintenance program or by typing commands
at the MS-DOS command prompt. For information about using the DriveSpace
program to manage compressed drives, see "Using DriveSpace to Manage
Compressed Drives" later in this file. For more information about managing
compressed drives from the MS-DOS command prompt, type HELP DRVSPACE at the
command prompt. For information about checking a compressed drive for disk
errors, type HELP SCANDISK at the MS-DOS command prompt.

You can also use DriveSpace to compress floppy disks, removable-media
drives, or additional hard disk drives. For more information, see
"Compressing Additional Drives" later in this file. 

The rest of this file explains how to set up and use DriveSpace. 

Getting Help
=========

DriveSpace includes extensive online help for commands, dialog boxes, and 
procedures. 

To get help while running DriveSpace:

 *  Press F1 when a DriveSpace screen, dialog box, or error message  		
    appears. 

To get help about the DRVSPACE command:

 *  Type HELP DRVSPACE at the command prompt. 

Setting Up DriveSpace
================

When you run DriveSpace for the first time, the DriveSpace Setup program 
starts. DriveSpace Setup compresses the data on the drive you select. After 
DriveSpace Setup is complete, your disk will have 50 to 100 percent more 
free space than it did before. 

Note  After you run DriveSpace Setup, you cannot use the Uninstall program 
         to restore your previous version of DOS. Do not set up DriveSpace 
         if you want to be able to use the Uninstall program. 

During DriveSpace Setup, you can select either Express Setup or Custom
Setup. To compress the existing files on drive C and have DriveSpace
determine the compression settings for you, choose Express Setup. To
compress a hard disk drive other than drive C, or to use the empty space on
an existing drive to create a new compressed drive, choose Custom Setup.
When you use Custom Setup, you can determine compression settings yourself.
For more information about running Custom Setup, see "Using Custom Setup"
later in this file. 

The following sections explain each setup method.

Using Express Setup
------------------------------

Express Setup is the easiest way to install DriveSpace. It compresses the 
existing files on drive C. (To compress the files on a drive other than C, 
use Custom Setup. For more information, see the following section.) 

Note  Before you run Express Setup, you should back up the files on drive 
         C. For information about using Microsoft Backup, see the chapter 
        "Managing Your System" in the Microsoft MS-DOS User's Guide. 

To install DriveSpace by using Express Setup:

1. Quit all running programs (including Windows). If you use a network, 
   start the network software and connect to any drives you usually use. 

2. Type DRVSPACE at the command prompt. The Welcome screen appears. 

3. To continue DriveSpace, press ENTER. 

   DriveSpace displays a screen that prompts you to choose between Express 
   and Custom Setup. 

4. Choose Express Setup by pressing ENTER. 

   DriveSpace displays a confirmation screen that estimates the amount of 
   time it will take to compress drive C. 

5. To compress drive C, press C. 

DriveSpace checks drive C for disk errors, and then defragments and 
compresses drive C. This process can take from several minutes to several 
hours, depending on the speed of your hard disk and processor and the 
amount of data your hard disk contains. Because DriveSpace checks and 
rechecks the validity of the data as it compresses your files, the process 
is very safe. In fact, if the compression process is accidentally 
interrupted (for example, by a power outage), DriveSpace will recover and 
continue without losing any data. During the compression process,
DriveSpace  Setup restarts your computer twice. 

When DriveSpace Setup is complete, it displays a screen that shows how long 
the compression process took and how much free space your new drive
contains. To quit DriveSpace after it has compressed drive C, press ENTER. 

After you set up DriveSpace, your computer's drives will be configured 
differently: 

 *  Drive C will be compressed and will contain more free space than it 
    did before. You will use drive C just as you did before you set up 
    DriveSpace. 

 *  Your computer will have a new drive that is not compressed. This drive 
    is used to store files that must remain uncompressed. For example, the 
    Windows permanent swap file does not work properly when it is
    compressed; if your Windows permanent swap file was previously located
    on drive C, DriveSpace moves it to the new uncompressed drive. 

DriveSpace also uses the new uncompressed drive to store important system 
files such as IO.SYS, MSDOS.SYS, DRVSPACE.BIN, DRVSPACE.INI, and
DRVSPACE.000. If you try to list the files on this drive, it will probably
appear empty. This is because most of the files it contains have the Hidden
attribute; many also have the Read-Only attribute. To view the files, type
DIR /A at the command prompt. 

CAUTION   Do not tamper with the hidden files on the new drive. If you 
		  change or delete these files, you might lose all the files on
		  drive C. 

For information about adjusting the configuration of your compressed drive, 
see "Using DriveSpace to Manage Compressed Drives" later in this file. For 
information about compressing additional drives, see "Compressing
Additional Drives" later in this file. For information about compressing
floppy disks, see "Using DriveSpace with Floppy Disks" later in this file. 

Using Custom Setup
------------------------------

Custom Setup gives you more control over the compression process than 
Express Setup does. You should use Custom Setup: 

 *  To compress the data on a hard disk other than drive C. 

 *  If you don't want to compress existing data. 
    
    Compressing existing data can take a long time. If you don't 
    want to compress your existing data, you can have DriveSpace 
    use some of the free space on an existing drive to create a new 
    compressed drive. This method does not compress existing data 
    and is much faster. 

 *  To determine compression settings yourself. 
    
    Depending on whether you are compressing an existing drive 
    or creating a new one, you can specify the drive letter for the 
    new drive, the estimated compression ratio, and the amount 
    of space to leave uncompressed. 


Note  Before you use Custom Setup to compress an existing drive, you should 
      back up the files on that drive. For information about using
      Microsoft Backup, see the chapter "Managing Your System" in the
      Microsoft MS-DOS User's Guide.

To install DriveSpace by using Custom Setup 
-----------------------------------------------------------------

1. Quit all running programs (including Windows). If you use a network, 
   start the network software and connect to any drives you usually use.

2. Type DRVSPACE at the command prompt. The Welcome screen appears. 

3. To continue DriveSpace, press ENTER. 

DriveSpace displays a screen that prompts you to choose between Express and 
Custom Setup. 

4. Select Custom Setup by pressing the DOWN ARROW key, and then press 
   ENTER. DriveSpace displays a screen in which you can choose between
   compressing an existing drive and creating a new compressed drive. For
   information about choosing a compression method, press F1. 

5. Select the compression method you want by pressing the UP ARROW or DOWN 
   ARROW key, and then press ENTER. 

   If your computer has more than one hard disk drive, DriveSpace displays
   a list of drives. If you chose to compress an existing drive, select the 
   drive you want to compress, and then press ENTER. If you are creating a 
   new compressed drive, select the drive that contains the free space 
   DriveSpace should use to create the new drive, and then press ENTER. 

   DriveSpace displays a screen that shows the default compression
   settings. 

6. If necessary, change the compression settings to suit your needs. To 
   change a setting, press the UP ARROW or DOWN ARROW key until the setting 
   is highlighted, and then press ENTER to display alternatives. For 
   information about compression settings, press F1. 

7. When all the settings are correct, press ENTER to continue DriveSpace. 
   DriveSpace displays a confirmation screen that estimates the amount of 
   time it will take to compress the drive or free space you selected. 

8. To begin the compression process, press C. 

DriveSpace checks the specified drive for disk errors, and then carries out 
the compression process with the settings you specified. This process can 
take from several minutes to several hours, depending on the speed of your 
hard disk and processor, the amount of data your hard disk contains, and 
whether you chose to compress existing data or create a new compressed 
drive. Because DriveSpace checks and rechecks the validity of the data as 
it compresses existing files, the process is very safe. In fact, if the 
compression process is accidentally interrupted (for example, by a power 
outage), DriveSpace will recover and continue without losing any data. 

During the compression process, DriveSpace Setup restarts your computer 
twice. 

When DriveSpace Setup is complete, it displays a screen that shows how long 
the compression process took and how much space your new drive contains. 
To quit DriveSpace after it has compressed the drive or free space you 
selected, press ENTER. 

After you set up DriveSpace, your computer's drives will be configured 
differently. The results differ depending on whether you chose to compress 
an existing drive or create a new compressed drive. 

If you chose to compress an existing drive
-------------------------------------------------------------

If you chose "Compress an existing drive" during Custom Setup: 

 *  The drive you selected will be compressed and will contain more free 
    space than it did before. You will use the compressed drive just as you 
    did before you set up DriveSpace. 

 *  Your computer will have a new drive that is not compressed. This drive 
    is used to store files that must remain uncompressed. For example, the 
    Windows permanent swap file does not work properly when it is
    compressed; 
    if your Windows permanent swap file was previously located on the drive 
    you compressed, DriveSpace moves it to the new uncompressed drive. 
    
DriveSpace also uses the new uncompressed drive to store important system 
files such as DRVSPACE.000. If you compressed drive C, the new uncompressed 
drive will also contain the IO.SYS, MSDOS.SYS, DRVSPACE.BIN and
DRVSPACE.INI files. If you try to list the files on this drive, it will
probably appear empty. This is because most of the files it contains have
the Hidden attribute; many also have the Read-Only attribute. To view the
files, type DIR /A at the command prompt. 

CAUTION  Do not tamper with the hidden files on the new drive. If you 
         change or delete these files, you might lose the files on your
         compressed drive. 

If you chose to create a new compressed drive
-------------------------------------------------------------------

If you chose "Create a new compressed drive" during Custom Setup: 

 *  Your computer will have a new compressed drive that is currently empty. 
    Although the new drive does use some disk space, it makes up for it by 
    providing more free space than it uses. 

 *  The drive that contained the free space you used to create the new 
    compressed drive will contain less free space than it did before. This 
    space is now being used by your new compressed drive, which is stored 
    in a hidden file with a filename such as DRVSPACE.001. 

For information about adjusting the configuration of your compressed drive, 
see "Using DriveSpace to Manage Compressed Drives" later in this file. For 
information about compressing additional drives, see "Compressing
Additional Drives" later in this file. For information about compressing
floppy disks, see "Using DriveSpace with Floppy Disks" later in this file. 


Understanding Disk Compression
========================

You don't need to know anything about disk compression to run DriveSpace 
Setup: just type DRVSPACE at the command prompt, follow the instructions on 
your screen, and DriveSpace takes care of the rest. 

However, if you want to adjust or modify your DriveSpace configuration, 
you need to understand some disk-compression concepts and terms. This 
section explains the terms you will encounter when you use DriveSpace to 
manage or modify your compressed drives. 


Compressed Volume Files and Host Drives
--------------------------------------------------------------

A compressed drive is not a real disk drive, although it appears that way
to most programs. Instead, a compressed drive exists on your hard disk as a 
compressed volume file (CVF). 

A CVF is a file with Read-Only, Hidden, and System attributes that contains 
a compressed drive. Each CVF is located on an uncompressed drive, which is 
referred to as the CVF's host drive. A CVF is stored in the root directory 
of its host drive and has a filename such as DRVSPACE.000. 

Most CVFs can store more data than the space they use on their host drives; 
for example, a typical CVF might use 10 MB of space on its host drive but 
contain 20 MB of compressed data. DriveSpace assigns a drive letter to the 
CVF so that you can use it as a disk drive and can access the files it 
contains. 

CAUTION  Do not tamper with a CVF. If you do, you might lose all the files 
	     on your compressed drive. 


How DriveSpace Calculates Free Space on a Compressed Drive
--------------------------------------------------------------------------------------------

On an uncompressed drive, free space indicates how much additional data you 
can store on that drive. For example, if a drive has 2 megabytes (MB) of 
free space, you can expect to fit 2 MB of data on it. However, the free 
space on a compressed drive is only an estimate of how much data you can
fit on that drive. 

When you store a file on a compressed drive, DriveSpace compresses the file 
so that it takes up as little space as possible. Some files can be
compressed more tightly than others; for example, a bitmap file can be
compressed much more than a program file. DriveSpace cannot detect the
compressibility of files you haven't stored yet, so it can only estimate a
compressed drive's free space. 

DriveSpace estimates a drive's free space by using the estimated
compression ratio, which you can set to specify the compressibility of the
files you plan to store. For example, if the estimated compression ratio is
set to 3 to 1, DriveSpace calculates the drive's free space based on the
assumption that the files you will store will be compressible at a 3-to-1
ratio ù that is, that each file can be compressed to one-third its original
size. 

Usually, the best compression estimate to use is the actual compression
ratio for the files already stored on the drive. From time to time, you
might want to reset the estimated compression ratio of each drive to match
that drive's actual compression ratio. To do this for all your compressed
drives, type DRVSPACE /RATIO /ALL at the command prompt. 

You might want to change the estimated compression ratio if it differs 
greatly from the actual compressibility of the files you plan to store. 
For example, if you plan to store extremely compressible files, such as 
bitmap files, you might want to specify a higher estimated compression 
ratio. Or, if you plan to store files that will not compress much further, 
you might specify a lower ratio. 

Note  Changing a drive's estimated compression ratio does not affect how 
      much DriveSpace actually compresses the files on that drive; it 
      changes only the way DriveSpace estimates the free space on the 
      compressed drive. 


Using DriveSpace to Manage Compressed Drives
============================================
Generally, you work with a compressed drive just as you would with an 
uncompressed drive. For example, saving, copying, and deleting files works 
the same way on both a compressed and an uncompressed drive. However, there 
are some tasks that you carry out only on compressed drives; for example, 
you can change the size of a compressed drive, but not that of an 
uncompressed drive. To maintain or modify compressed drives or to create 
additional compressed drives, use the DriveSpace maintenance program, which 
provides a full-screen interface with easy-to-use menu commands. 

You can also manage compressed drives from the MS-DOS command prompt 
by using switches with the DRVSPACE command. For more information, type 
HELP DRVSPACE at the command prompt. 

To start the DriveSpace program:

 *  Type DRVSPACE at the command prompt. 

The main DriveSpace screen appears. This screen lists your existing 
compressed drives. You can work with these drives, compress additional 
drives, or create new compressed drives. From this screen, you can carry 
out the following tasks: 

 *  Work with a compressed drive. To do this, select the drive by clicking 
    it with your mouse or by pressing the UP ARROW or DOWN ARROW key until 
    the drive you want is selected. Then, choose the command you want from 
    the Drive or Tools menu. (For a description of the commands on these 
    menus, see the tables later in this section.) 

 *  Compress an existing drive. To do this, choose the Existing Drive 
    command from the Compress menu. Use this command to compress files on 
    a hard disk drive or floppy disk. For more information, see
    "Compressing Additional Drives" later in this file. 

 *  Add a new compressed drive. You can create a new compressed drive by 
    using free space on an existing drive; to do this, choose the Create
    New Drive command from the Compress menu. For more information, see 
    "Compressing Additional Drives" later in this file. (You can also add a 
    compressed drive by mounting an unmounted compressed volume file. For 
    more information, see "Creating a New Compressed Drive" later in this 
    file.) 

The Drive menu includes commands you can use to work with the selected 
drive. The following list describes the commands on the Drive menu. 

Info
     Displays information about the selected drive. When you choose this 
     command, the Compressed Drive Information dialog box appears 
     and displays information about the drive's free and used space, 
     the name of its CVF, its actual and estimated compression ratios, 
     and other information. You can also display the Compressed Drive 
     Information dialog box by double-clicking the name of the drive or 
     by pressing ENTER when the drive is selected. For more information, 
     press F1 when the Compressed Drive Information dialog box is on 
     your screen. 

Change Size
     Enlarges or reduces the size of the selected drive. Unlike an 
     uncompressed drive, you can change the size of a compressed drive. 
     You might want to enlarge a compressed drive if its host drive 
     contains a lot of free space. You might want to reduce the size of a 
     compressed drive if you need more free space on the host drive. For 
     more information, choose the Change Size command, and then press F1. 

Change Ratio
     Changes the estimated compression ratio of the selected drive. 
     DriveSpace uses this ratio to estimate how much free space 
     the compressed drive contains. You might want to change the 
     estimated compression ratio if you plan to store new files with a 
     compression ratio that differs greatly from the current ratio. For 
     more information, choose the Change Ratio command and then 
     press F1. 

Mount
     Establishes a connection between a compressed volume file and a 
     drive letter, so you can use the files the CVF contains. DriveSpace 
     usually mounts CVFs automatically. You need to mount a CVF only 
     if you previously unmounted it, or if the CVF is located on a floppy 
     disk and you turned off the Enable Automounting option. For more 
     information, choose the Mount command, and then press F1. For 
     more information about using DriveSpace with floppy disks, see 
     "Using DriveSpace with Floppy Disks" later in this file. 

Unmount
     Breaks the connection between the selected drive's CVF and its 
     drive letter. Unmounting a drive makes it temporarily inaccessible. 
     For more information, choose Index from the Help menu, and then 
     select the topic "Unmounting a Compressed Drive." 

Format
     Formats the selected compressed drive. Like formatting an 
     uncompressed drive, formatting a compressed drive deletes all 
     the files it contains. For more information, choose the Index 
     command from the Help menu, and then select the topic 
     "Formatting." For more information about using compressed 
     floppy disks, see "Using DriveSpace with Floppy Disks" later in 
     this file. 

Delete
     Deletes the selected compressed drive and the associated CVF. 
     Deleting a compressed drive erases it and all the files it contains. 
     For more information, choose the Index command from the Help 
     menu, and then select the topic "Deleting a Compressed Drive." 
     
Exit
     Quits the DriveSpace program. (MS-DOS continues to provide 
     access to your compressed drives after you quit DriveSpace.) 

The Compress menu contains commands you can use to create additional 
compressed drives or to compress floppy disks. For information about 
compressing additional drives, see the following section, "Compressing 
Additional Drives." For information about compressing and working with 
floppy disks, see "Using DriveSpace with Floppy Disks" later in this file. 

The Tools menu includes commands you can use to maintain compressed 
drives. The following list describes the commands on the Tools menu. 

Defragment
     Defragments the selected compressed drive. Defragmenting a 
     compressed drive consolidates the free space on it. If you are 
     planning to reduce the size of a compressed drive, you should first 
     use the Defragment command to consolidate the drive's free 
     space. You might also need to use the Defragment command if 
     your compressed drive is running out of disk space. For more 
     information, choose the Defragment command, and then press F1. 

Uncompress
     Uncompresses a drive that was compressed by using DriveSpace. 
     When you uncompress the last mounted drive, DriveSpace also 
     removes DRVSPACE.BIN from memory. (DRVSPACE.BIN is 
     the portion of MS-DOS that provides access to compressed 
     drives. It uses about 50K of memory.)
     
Options
     Displays the DriveSpace Options dialog box, in which you 
     can enable or disable the DoubleGuard and Automount features. 
     The Options dialog also enables you to change other settings. For 
     more information, choose the Options command, and then press 
     F1 when the DriveSpace Options dialog box is on your screen. 
     

Compressing Additional Drives
======================

DriveSpace provides two ways to add compressed drives. You can: 

 *  Compress an existing hard disk drive or floppy disk. 

 *  Create a new, empty compressed drive by using free space on an 
    existing drive. 

The rest of this section explains each method. 


Compressing an Existing Drive
-----------------------------
You can use DriveSpace to compress the files on existing hard disk drives, 
floppy disks, or other removable media. Compressing an existing drive makes 
more space available on that drive. 

Note  Before you compress an existing drive, you should back up the files 
      on that drive. For information about using Microsoft Backup, see the 
      chapter "Managing Your System" in the Microsoft MS-DOS User's Guide.

To compress an existing drive:

1. In the main DriveSpace screen, choose the Existing Drive command from 
   the Compress menu. (If you are compressing a floppy disk or other 
   removable media, make sure it is formatted and is in the drive before 
   you choose the Existing Drive command.) 

   DriveSpace scans your computer and then displays a list of drives that 
   can be compressed. (The list does not include drives that are too full 
   to be compressed, compressed drives, network drives, CD-ROM drives, 
   Interlnk drives, or paths that have been associated with a drive letter 
   by using the SUBST command. For more information, press F1 when this 
   list is displayed.) 

2. Select the drive you want to compress by pressing the UP ARROW or DOWN 
   ARROW key, and then press ENTER. 

   A screen appears, giving you the opportunity to change the settings 
   DriveSpace will use to compress the drive. 

3. Change the settings as needed. For more information about changing 
   settings, press F1. 

4. When you have finished changing settings, press ENTER. 

   DriveSpace displays a confirmation screen stating that it is ready to 
   compress the drive. 

5. To compress the drive, press C. 

DriveSpace checks the specified drive for disk errors, defragments and 
compresses it, and then restarts your computer so your new drive 
configuration can take effect. 


Creating a New Compressed Drive
-------------------------------
If your hard disk drive contains a lot of uncompressed space, you might
want to convert that unused space into a new compressed drive. The new
drive will provide more storage capacity than the amount of space it uses. 

To convert free space into a new compressed drive:

1. From the main DriveSpace screen, choose the Create New Drive command 
   from the Compress menu. 

   DriveSpace scans your computer and then displays a list of uncompressed 
   drives that contain free space. (The list does not include uncompressed 
   drives that are too full to be compressed, network drives, CD-ROM
   drives, Interlnk drives, or paths that have been associated with a drive
   letter by using the SUBST command.) The list shows the free space on
   each uncompressed drive and how large the new compressed drive will be. 

2. Select the drive that contains the space you want to use, and then press 
   ENTER. A screen appears, giving you the opportunity to change the 
   settings DriveSpace will use when it creates the new compressed drive. 

3. Change the settings as needed. For more information about changing 
   settings, press F1. 

4. When you have finished changing settings, press ENTER. A confirmation 
   screen appears. 

5. To create the new compressed drive, press C. 

DriveSpace creates the new compressed drive, and then updates the list of 
drives on the main DriveSpace screen to include the new compressed drive. 


Using DriveSpace with Floppy Disks
==========================

You can use DriveSpace to increase the storage capacity of floppy disks. 
After compressing a floppy disk, you can use it to store data or to 
transfer data from one computer to another. 

Note  To use a compressed floppy disk to transfer data from one computer 
      to another, both computers must be using DriveSpace. 


Compressing a Floppy Disk
-----------------------------------------
Compressing a floppy disk is similar to compressing a hard disk drive. You 
can compress a floppy disk that is completely empty or one that contains 
files. (However, you cannot create a new compressed drive on a floppy
disk.)

Note  Make sure the floppy disk is formatted and has at least .65 MB of 
      free space. DriveSpace cannot compress a 360K disk, an unformatted 
      disk, or a disk that is completely full. 

To compress a floppy disk:

1. Insert a formatted disk in a floppy disk drive. 

2. In the main DriveSpace screen, choose the Existing Drive command from 
   the Compress menu. 

   DriveSpace scans your computer and then displays a list of drives that 
   can be compressed. (If the list does not include the floppy disk you
   just inserted, make sure the disk is formatted and has at least .65 MB
   of free space.) 

3. Select the drive that contains the floppy disk you want to compress by 
   pressing the UP ARROW or DOWN ARROW key, and then press ENTER. 

   DriveSpace displays a confirmation screen stating that it is ready to 
   compress the drive you selected. 

4. To compress the floppy disk, press C. 

   DriveSpace checks the floppy disk for errors. Then it defragments, 
   compresses, and mounts the floppy disk, and updates the list of drives 
   on the main DriveSpace screen to include the newly compressed disk. 

After DriveSpace finishes compressing the floppy disk: 

 *  The floppy disk will contain more free space than it did before. You 
    use the floppy disk just as you did before you compressed it, except 
    that if you change floppy disks or restart your computer, you must 
    remount the floppy disk. For more information about using a compressed 
    floppy disk, see the following section. 

 *  Your computer will have a new drive letter. This new drive letter 
    represents the compressed floppy disk's host drive, which contains the 
    floppy disk's CVF. Both the new drive letter and the original drive 
    letter are associated with the same physical floppy disk drive. For 
    more information, see "Understanding Disk Compression" earlier in this 
    file. 


Using a Compressed Floppy Disk
-------------------------------------------------

In general, you use a compressed floppy disk just as you would an 
uncompressed floppy disk. 

By default, DriveSpace automatically mounts a compressed floppy disk when 
you try to use that disk. This makes it possible to use the disk as if it 
were an uncompressed floppy disk. (However, if you turn off the Enable 
Automounting option in the Options dialog box, you must mount compressed 
floppy disks yourself. For more information, see the following section.)

To gain access to the contents of a compressed floppy disk, insert the 
floppy disk in the drive, and then use a command such as the DIR command 
(for example, if the disk is in drive A, type DIR A:).


Using Compressed Floppy Disks Without Automounting
--------------------------------------------------------------------------------

If you rarely use compressed floppy disks, you might want to disable the 
Automounting feature. When Automounting is enabled, it uses about 4K of 
memory.

To disable Automounting, choose DriveSpace Options from the Tools menu, and 
then clear the Enable Automounting check box.

Note  Before it is mounted, a compressed floppy disk appears nearly full. 
          If you have turned off the Enable Automounting option and you change 
          to the floppy disk drive and carry out the DIR command, MS-DOS 
         usually lists one file: a text file named READTHIS.TXT, which briefly 
         explains how to mount the floppy disk. The DIR command usually
         reports that the floppy disk contains almost no free space, since
         most of the space is used by the CVF. The CVF is a file with Hidden,
         Read-Only, and System attributes named DRVSPACE.000. 

When Automounting is disabled, you can still use compressed floppy disks, 
but you must mount them yourself. You can do this either from the main 
DriveSpace screen or at the MS-DOS command prompt. 

To mount a compressed floppy disk from the main DriveSpace screen:

1. Insert the compressed floppy disk in a drive. 

2. In the main DriveSpace screen, choose the Mount command from the 
   Drive menu. 

DriveSpace searches your computer for unmounted CVFs and lists the ones it 
finds. 

3. Select the CVF that is located on your compressed floppy disk by using 
   the UP ARROW or DOWN ARROW key, and then press ENTER. 

4. DriveSpace mounts the CVF and then updates the list of compressed 
   drives on the main DriveSpace screen to include the newly mounted 
   floppy disk. 

The compressed floppy disk remains mounted, and the files on it remain 
available, until you change floppy disks or restart your computer. 

To mount a compressed floppy disk at the MS-DOS command prompt:

1. Insert the compressed floppy disk in a drive. 

2. At the command prompt, type DRVSPACE /MOUNT and the letter of the drive 
   the floppy disk is in. For example, to mount the compressed floppy disk 
   in drive A, you would type DRVSPACE /MOUNT A:.

The compressed floppy disk remains mounted until you change floppy disks or 
restart your computer. 

If you want, you can include the DRVSPACE /MOUNT command in your
AUTOEXEC.BAT file. For example, if you usually keep a compressed floppy
disk in drive B and want to mount it each time you start your computer, you
could add the command DRVSPACE /MOUNT B: to your AUTOEXEC.BAT file. For
more information about your AUTOEXEC.BAT file, see the chapter "Configuring
Your System" in the Microsoft MS-DOS User's Guide. 


Getting Information About Compressed Drives
=================================

You can display information about your compressed drives in several ways: 

 *  In DriveSpace, choose the Info command from the Drive menu to display 
    detailed information about a compressed drive. For more information, 
    press F1 while the Compressed Drive Information dialog box is on your 
    screen. (You can also display detailed information about a drive by 
    typing DRVSPACE /INFO at the command prompt; for more information about 
    this command, type HELP DRVSPACE /INFO.)

 *  At the MS-DOS command prompt, change to the compressed drive you want 
    information about, and then type DIR /C. MS-DOS lists the files in the 
    current directory and displays the actual compression ratio for each 
    file. It also shows the average compression ratio for the entire list 
    of files. (If the compressed drive is empty, DIR /C does not display 
    compression information.) For more information, type HELP DIR at the 
    command prompt. 

 *  At the MS-DOS command prompt, type DRVSPACE /LIST to see a list of your 
    computer's drives and their compression status. This command lists and 
    briefly describes all your computer's drives (except network drives). 
    Use this command to get a more complete picture of your computer's
    drive configuration. 

 *  If you use Windows, choose DriveSpace Info from the Tools menu in File 
    Manager. For more information, press F1 while the DriveSpace Info
    dialog box is on your screen. 


Understanding DriveSpace and Memory
============================

When you start your computer, MS-DOS loads DRVSPACE.BIN into memory. 
DRVSPACE.BIN is the part of MS-DOS that provides access to your compressed 
drives. It requires about 50K of memory. MS-DOS loads DRVSPACE.BIN, along 
with other operating system functions, before carrying out the commands in 
your CONFIG.SYS and AUTOEXEC.BAT files. Initially, DRVSPACE.BIN loads at 
the top of conventional memory. By default, MS-DOS moves DRVSPACE.BIN to 
the bottom of conventional memory after carrying out the commands in the 
CONFIG.SYS file.

You can use the DRVSPACE.SYS device driver to move DRVSPACE.BIN to a 
specific area of memory. (The DRVSPACE.SYS device driver does not provide 
access to compressed drives; it simply determines the final location in 
memory of DRVSPACE.BIN.) (DriveSpace Setup automatically adds a DEVICE 
command for the DRVSPACE.SYS device driver to your CONFIG.SYS file.)

There are two reasons you might want to use DRVSPACE.SYS to move 
DRVSPACE.BIN from the top of conventional memory: 

 *  To avoid conflicts with programs that require access to the top of 
    conventional memory. 

    A few programs require access to the top of conventional memory and 
    do not work properly if DRVSPACE.BIN is located there.

 *  To free conventional memory. 

    If your computer has extended memory, DRVSPACE.SYS can move part of 
    DRVSPACE.BIN to the high memory area (HMA). (By default, MS-DOS 
    Setup and DriveSpace Setup configure your computer this way.) In 
    addition, if you have an 80386 or higher computer with extended 
    memory, you can run the MemMaker program to move the rest of 
    DRVSPACE.BIN to the upper memory area. (For instructions on how to 
    run MemMaker, see the chapter "Making More Memory Available" in the 
    Microsoft MS-DOS User's Guide.)

For more information about DRVSPACE.SYS and DRVSPACE.BIN, type HELP 
DRVSPACE.SYS at the MS-DOS command prompt.


Getting More Information About DriveSpace
===============================

For tips on using DriveSpace and answers to common questions about 
DriveSpace, type HELP DRVTIPS at the command prompt.

For information about using the DRVSPACE command, type HELP DRVSPACE at the 
command prompt.

For information about using the DriveSpace program, press F1 while the 
DriveSpace program is running.

For technical information about DriveSpace, including information about 
writing programs that use MRCI (Microsoft Real-Time Compression Interface), 
obtain the Microsoft MS-DOS Resource Kit. For details, see the coupon in 
the back of your Microsoft MS-DOS User's Guide.

Troubleshooting DriveSpace
==========================
If you encounter problems while running DriveSpace, or if you encounter 
problems with your compressed drives, see the DriveSpace section of the 
README.TXT file. The README.TXT file is located in the directory that 
contains your MS-DOS files. 

If you encounter disk errors on a compressed drive, run the ScanDisk 
program on that drive. For more information about ScanDisk, type 
HELP SCANDISK at the command prompt.