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Windows FAQ Sheet 
(Covers Windows 95 and Windows NT)
Western Digital Technical Support (http://www.wdc.com/support)
This document was last modified on Saturday, 01-Mar-97 14:06:56 PDT
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1: Can I install Windows 95 on my Caviar drive that dual-boots Windows NT and 
MS-DOS? 
2: Can I install Windows 95 and still boot MS-DOS and Windows 3.1? 
3: Can I install Windows 95 on a computer running IBM OS/2? 
4: Can I remove Windows 95? 
5: After installing Windows 95, I can no longer boot from a different hard drive. 
What 
has changed? 
6: Can I install Windows 95 over Windows NT? 
7: After I install Windows 95 on a computer with Windows NT, how do I start 
Windows 95? 
8: During the first boot of Windows 95, I get "Invalid System Disk" error message. 
What 
does this mean? 
9: Can I dual-boot Windows 95 and OS/2 Warp? 
10: Will Windows 95 Setup work if I compressed my hard disk with disk compression 
utilities? 
11: Will Windows 95 install correctly on a drive with Ontrack Disk Manager? 
12: I have "Brand X" system and my hard disk is using MS-DOS compatibility mode. 
What is the problem? 
13: Disabling Protected-Mode disk driver(s), hides the partition table when I run 
Fdisk? 
What can I do?
14: What are some possible scenarios under which Windows 95 might run in MS-DOS 
compatibility mode on my EIDE hard drive and how can I fix the problem? 
15: Why don't I get 32-bit disk access on my 1GB hard drive running Windows 95? 
16: How do I install Windows 95 with Disk Manager already present on my hard drive? 
17: How do I install my new drive in a Windows 95 system? 
18: Windows 95 reports that I am operating in DOS Compatibility Mode. What is the 
problem and how can I fix it? 
19: I use Western Digital's Fastdisk driver WDCDRV.386 for 32-Bit Disk Access in 
Windows 3.1x. Do I need to use this driver with Windows 95? 
20: Does ScanDisk in Windows 95 support drives with cluster sizes larger than 8K? 
21: Can I use third party software utility packages, like Norton Utilities with my 
Western Digital hard drives under Windows 95? 
22: Can I use my pre-Windows 95 memory manager with Windows 95 to manipulate 
where Disk Manager driver loads? 
23: Do I need to use Disk Manager or EZ-Drive to support large Enhanced IDE hard 
drives under Windows 95? 
24: What version(s) of Disk Manager will function properly with Windows 95? 
25: I installed Microhouse Fastdisk driver, Mh32bit.386 and now Windows 95 reports 
DOS Compatibility mode. What can I do to fix this? 
26: My DriveSpace 3-compressed slave drive does not boot after I made it my master 
drive. I get "invalid drive" error message. What is wrong? 
27: I am adding a new Caviar drive but DriveSpace 3 is unable to decompress my existing 
Caviar drive. What should I do? 
28: How can I copy the contents of my old drive to my new drive and make the new drive 
the Master drive in Windows 95?

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1: Can I install Windows 95 on my Caviar drive that dual-boots 
Windows NT and MS-DOS? 

Yes. To install Windows 95 on a computer that dual-boots Windows NT and MS-DOS, 
start the computer in MS-DOS mode and run Setup either in Windows 3.1 or at an MS-
DOS prompt. You cannot install Windows 95 in a directory with a shared Windows 3.1 
and Windows NT configuration. In this situation, you must install Windows 95 in a 
different directory. 

If your computer boots Windows NT, you must configure the computer to dual-boot MS-
DOS and Windows NT and then follow the instructions in the paragraph above. If you 
start the computer from an MS-DOS disk and then run Setup, you will no longer be able 
to boot Windows NT. However, you can restore Windows NT by starting the computer 
from the Windows NT Boot/Repair disk and then selecting the Repair option. 

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2: Can I install Windows 95 and still boot MS-DOS and Windows 3.1?

Windows 95 supports booting the earlier version of the operating system if you 
are using MS-DOS version 5.0 or later or IBM PC-DOS version 5.0 or later. You 
cannot boot an earlier version of DR DOS. When you install Windows 95 in a new 
directory, Setup automatically makes the required adjustments so the computer 
can dual-boot Windows 95 and MS-DOS. To boot MS-DOS on a Windows 95 computer 
with dual-boot enabled, press F4 or F8 when you see the "Starting Windows 95" 
message. 

If you install Windows 95 in a new directory, you must re-install all your 
Windows-based programs for them to run properly in Windows 95. However, if you 
upgrade your earlier version of Windows to Windows 95, you do not need to 
re-install your Windows-based programs because the registry information is 
transferred to Windows 95. 

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3: Can I install Windows 95 on a computer running IBM OS/2?

Setup does not run in OS/2. However, you can install Windows 95 on a computer 
running OS/2 if you boot to MS-DOS and run Setup from the MS-DOS prompt. You 
cannot install Windows 95 in the same directory as OS/2. Because Windows 95 
cannot access HPFS partitions, a FAT partition must be available to install 
Windows 95. You can also run Windows 95 Setup if you boot from a MS-DOS diskette. 

Windows 95 Setup disables Boot Manager to ensure that it can restart the computer 
and complete the installation. You can re-activate Boot Manager by running the 
Fdisk tool that is shipped with Windows 95. 

If you do not use OS/2 Boot Manager, you must configure your computer to use
Boot Manager and then follow the steps above. 

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4: Can I remove Windows 95? 

Yes. During Setup, you are prompted whether you want to save your computer's 
system files. If you choose to save the system files, Setup saves them in a hidden, 
compressed file on the hard disk. You will not be asked to save the system files if 
a)you are installing Windows 95 in an empty directory, b)you are not running MS-DOS 
version 5.0 or later or c)you are re-installing Windows 95 over itself. 

To remove Windows 95, follow these steps: 

Click the Start button, point to Settings, and then click Control Panel. 
Double-click the Add/Remove Programs icon. On the Install/Uninstall tab, click 
Windows 95, and then click Remove. 

You can also remove Windows 95 by starting your computer with the Windows 95 
Startup Disk and then typing uninstall at the command prompt. 

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5: After installing Windows 95, I can no longer boot from a 
different hard drive. What has changed?

Windows 95 Setup program checks all the hard disks in your computer to make sure 
that only one contains 80h in the DriveNumber field of the boot sector. Setup makes 
this change so that Windows 95 can find the boot disk when you start the computer 
and recognize the other drives. 

You can use either of the following methods to correct the DriveNumber field: 

- Use the Fdisk program that is included with Windows 95 to set the primary active 
partition.
- Use a disk editor to change a disk's DriveNumber field so that you can boot from that 
hard disk. 

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6: Can I install Windows 95 over Windows NT?

You cannot install Windows 95 in the same directory as Windows NT. To install 
Windows 95, boot to MS-DOS, then run Windows 95 Setup. After you install Windows 
95 to a different directory, you can boot either Windows 95 or Windows NT. 

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7: After I install Windows 95 on a computer with Windows NT, 
how do I start Windows 95?

When you start your computer, you are given a choice to run Windows NT or MS-DOS. 
Choose MS-DOS to load Windows 95. 

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8: During the first boot of Windows 95, I get "Invalid System 
Disk" error message. What does this mean?

If during the first reboot in Windows 95 Setup or when you boot from the start-up 
disk, you receive the following error message: 

Invalid system disk
Replace the disk, and then press any key

your system may be: 

- infected with a boot-sector virus
- running virus-protection software
- using hard disk management software (such as Disk Manager, EZ-Drive, or DrivePro) 
for Logical Block Addressing (LBA) support. These tools provide support for hard 
disks with more than 1024 cylinders. 

To correct the problem if the system is Infected with a Virus, use an anti-virus 
program to detect and remove the virus, and then re-install Windows 95 system files. 

If the systems is running Virus-Protection Software, Boot the system using the 
startup disk created during Windows 95 Setup. Use the SYS command from the startup 
disk to restore the system files to the hard disk. 

Windows 95 may not detect disk management software and may overwrite the master 
boot record (MBR). Refer to the documentation for the disk management software you 
are using for information about restoring the MBR. 

To re-install the Windows 95 system files, follow these steps: 

1. Boot the system using the Windows 95 Emergency Boot Disk.
2. At the MS-DOS command prompt, type the following lines:


c:
cd\windows\command
attrib c:\msdos.sys -h -s -r
ren c:\msdos.sys c:\msdos.xxx
a:
sys c:
del c:\msdos.sys
ren c:\msdos.xxx c:\msdos.sys
attrib c:\msdos.sys +r +s +h

3. Remove the Emergency Boot Disk and reboot the system. 

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9: Can I dual-boot Windows 95 and OS/2 Warp?

To dual boot between Windows 95 and IBM OS/2 you must reset or re-install the OS/2 
Boot Manager. Please consult your OS/2 documentation for information about enabling 
Boot Manager. 

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10: Will Windows 95 Setup work if I compressed my hard disk 
with disk compression utilities?

Windows 95 is compatible with Stacker version 2.0 and higher, and with all versions 
of SuperStor. Before you start Setup, make sure there is enough free hard disk space 
on the host drive. For further details, please consult your compression utility 
software documentation. 

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11: Will Windows 95 install correctly on a drive partitioned with 
Ontrack Disk Manager?

Windows 95 is compatible with Disk Manager versions 6.03 and later, however, if 
you are currently using version 6.03 through 6.03c of the Disk Manager, download 
Dmpatch.exe to update the Disk Manager drivers. If you use version 6.03d of Disk 
Manager, Windows 95 automatically uses its protected-mode driver. 

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12: I have "Brand X" system and my hard disk is using MS-DOS 
compatibility mode. What is the problem?

Windows 95 may use DOS Compatibility Mode on large EIDE hard disks (hard disks 
with more than 1024 cylinders) in some computers. This situation may occur because of 
invalid drive geometry translation in the system ROM BIOS that prevents the protected-
mode IDE device driver from being loaded. Please contact your system manufacturer for 
information about obtaining an updated BIOS. 

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13: Disabling Protected-Mode disk driver(s), hides the partition 
table when I run Fdisk? What can I do?

If this is happens in your system, do not use the "Disable all 32-bit 
protected-mode disk drivers" option, or upgrade your computer's BIOS to a later 
version. 

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14: What are some possible scenarios under which Windows 95 
might run in MS-DOS compatibility mode on my Enhanced IDE 
hard drive and how can I fix the problem?

The IOS.INI file, located in the Windows directory, contains a list of device 
drivers that Windows 95 can safely remove from the Config.sys file and replace 
with its protected mode IDE device driver(ESDI506.PDR.) If the real mode device 
driver name is not present in the IOS.INI file, Windows 95 will use the real mode 
device driver in the Config.sys file and the devices attached to the controller will 
operate in MS-DOS Compatibility Mode. 

If you add the name of the real mode device driver for the Enhanced IDE controller 
to the Ios.ini file to get Window 95 to operate the device in protected mode, you 
may risk data loss, data corruption and performance degradation. 

The Windows 95 protected mode IDE driver needs to use the Int13 hardware interface 
to communicate with the IDE controller. If another device driver is intercepting 
these calls, the Windows 95 protected mode driver will not be able to communicate 
directly with the device. As a result all devices attached to the controller will 
use MS-DOS Compatibility Mode. 

To check if there is a device driver or if any other program is intercepting Int13 
calls: 

Download Getcmos.exe to determine Int13h, Int41h and Int46h values. Unpack and run 
this program at the command prompt to determine which driver is the Int13 hooker. 
Open the Ios.log file located in the Windows directory with any text editor. You will 
only find Ios.log only if there is a device using MS-DOS Compatibility Mode. 
Search for the line MBRINT13 to determine which device driver is intercepting calls to 
Int13: 

Boot the system and press the F8 function key to display the boot menu. Choose 
step-by-step Confirmation to selectively load drivers. This will help you to determine 
which driver may be responsible for the problem. 

If you are not able to locate the driver in question, it is possible that a virus is 
interfering with protected-mode support. If a virus is present on the system, or in 
its Master Boot Record (MBR), Windows 95 will receive incorrect information about the 
EIDE controller and the device(s) connected to it and will fail to load the protected 
mode device driver. 

Run a virus detector to clean the system. If your MBR is not infected by any viruses, 
It is possible that the manufacturer of the EIDE controller has drivers for 32-bit Disk 
Access for Windows 3.1x. 

Lastly, your EIDE controller itself may be causing the compatibility issue. It is 
possible by selecting different modes of operation (i.e. Normal, Fast, Turbo, etc.) 
you may be able to correct the problem. Please contact your controller card manufacturer 
for further instructions. 

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15: Why don't I get 32-bit disk access on my 1 GB hard drive in 
Windows 95?

Make sure there is no conflict between the motherboard CMOS setup and the controller 
BIOS settings. (i.e. if both the motherboard and the controller have settings for 
Logical Block Addressing, LBA, make sure only one is in use.) 

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16: How do I install Windows 95 with Disk Manager already 
present on my hard drive?

The following information applies only to Disk Manager version 6.03 and later. An 
end-user with a version earlier than 6.03 will not benefit from the following 
information. They will need to upgrade to a version 6.03 or later. 

There are four possible configurations when installing Windows 95 in a system 
using Disk Manager: 

1. A single hard drive using Disk Manager 
2. A master drive using Disk Manager in a dual drive system 
3. A master and slave drive using Disk Manager in a dual drive system 
4. A slave drive using Disk Manager in a dual drive system. 

The first three configurations, where a master or single boot drive utilize Disk 
Manager, should experience no problems when installing Windows 95 onto the drive. 
The overlay will load, revealing the familiar Western Digital blue banner as usual, 
and Windows 95 will acknowledge the presence of the overlay and recognize the drive 
accordingly. Entering Windows 95 Control Panel and choosing Performance under the 
System option reveals a file system in running 32-Bit Protected-mode. 

The last configuration functions properly except for a few exceptions. According 
to Ontrack test results, the Windows 95 file system does not function properly 
under three unique conditions where only the slave drive has been set up using 
Disk Manager: 

1.  When a Windows 3.1x virtual driver replaces the Windows 95 Protected-
mode driverWDCDRV.386 included) 
2.  When the cylinder count in the CMOS for the slave drive is greater than 1024    
cylinders. 
3.  When the CMOS setting for the slave drive are set to auto-detect. 
	
Windows 95 ensures that all essential drivers in the system files, function properly 
even though Windows 95 does not recognize or have an equivalent. Both hard drives 
will now strictly use the BIOS for access with a reduction in system performance. 

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17: How do I install my new drive in a Windows 95 system?

The standard Fdisk and Format procedure is adequate to configure a drive for use. 
There is no graphical equivalent of Fdisk in Windows 95, therefore DOS is still 
the only interface to manipulate the partitions on the drive. You can run the 
Fdisk command from the Run option under Start on the Taskbar. Create your 
partition(s) then press ESC. Unlike DOS, Windows 95 does not reboot the system 
at this juncture. Exit the DOS window, restart the system. 

Once the system has booted back up, proceed to format the drive. There are a 
number of ways you go about doing this. You can format the hard drive using the 
Format command. Type:

format [drive letter] /[switch] 

at the RUN option under Start. You can also format the drive by double-clicking 
the MY COMPUTER icon, and then click the icon for the disk you want to format. 
Be sure not to double-click the disk icon, because you cannot format a disk if 
it is open in MY COMPUTER or Windows Explorer. On the File menu, click Format. 

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18: Windows 95 reports that I am operating in DOS compatibility 
Mode. What is the problem and how can I fix it?

DOS Compatibility Mode is invoked by Windows 95 whenever the system loads a real 
mode driver. This would happen when Windows 95 does not have an equivalent 32 bit 
protected mode driver to replace the real mode driver. Click on Performance tab 
under the System icon for details on what devices are affected when there is an 
irreplaceable device driver. Highlight the message in the details box and click 
the Details button for information on that particular issue. The first place to 
check for questionable driver(s) is your CONFIG.SYS and AUTOEXEC.BAT files. Once 
you discover these drivers, contact the developer/manufacturer of the driver for 
updated Windows 95 compliant driver(s). 

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19: I use Western Digital's Fastdisk driver WDCDRV.386 for 32-Bit Disk Access in 
Windows 3.1x. Do I need to use this driver in Windows 95?

Windows 95 has built in 32 bit protected mode support for your Western Digital 
hard drives and other EIDE peripherals. Hence, you do not need to load WDCDRV.386 
in Windows 95. If Windows 95 has not removed any reference to 32-Bit Disk Access 
or WDCDRV.386 from System.ini file, you should manually edit this file and remove 
any reference to 32-Bit Disk Access or WDCDRV.386. 

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20: Does ScanDisk in Windows 95 support drives with cluster sizes larger than 8K?

Yes, the new Windows 95 version of ScanDisk supports large EIDE drives and large 
partitions with greater than 8KB per cluster size. 

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21: Can I use third party software utility packages, like Norton 
Utilities with my Western Digital hard drives under Windows 95?

Absolutely, but you should upgrade to "Made for Windows 95" versions of these 
software packages before running them under Windows 95. Please contact the 
respective manufacturer of your favorite utility software for their Windows 95 
version. However, we recommend Wddiag.exe as it is better prepared to recognize 
and report any issues with your hard drive. 

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22: Can I use my pre-Windows 95 memory manager with Windows 95 to manipulate 
where Disk Manager driver loads?

Windows 95 runs in a virtual memory environment and the Disk Manager driver will 
not create any conflicts with this setup. Each DOS sessions is assigned its own 
virtual machine that simulate a conventional real mode memory scheme. The amount 
of memory allocated to a particular application can be modified by the user. This 
allows even your most memory intensive DOS programs to run well within Windows 95. 
For details on how your memory package interacts with the Window 95 environment 
and how to properly configure your system for their use, contact the manufacturer 
of the software. Quarterdeck can be reached at 310) 392-9701 and Qualitas (386MAX) 
at 301) 907-6700. 

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23: Do I need to use Disk Manager or EZ-Drive to support large 
Enhanced IDE hard drives under Windows 95?

To get the full capacity of your hard drive under Windows 95, you must have 
either hardware support (a translating system BIOS or an Enhanced IDE controller 
card), or software support such as Disk Manager. Windows 95 does support and 
recognize Disk Manager versions 6.03 and greater. The Disk Manager driver, is 
loaded from the Master Boot Record (MBR) when the drive is in the master position, 
or in the Config.sys as a device driver when the drive is in the slave position. 

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24: What version(s) of Disk Manager function properly with Windows 95?

Disk Manager versions 6.03 or higher will function properly with Windows 95. 
Western Digital recommends downloading Dmpatch.exe from our Online Services and 
updating the Dynamic Drive Overlay to 6.03d. 

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25: I installed Microhouse Fastdisk driver, Mh32bit.386 and now Windows 95 
reports DOS Compatibility mode. What can I do to fix this?

Disable the line that loads the Mh32bit.386 device driver in the System.ini file. 
To do so, follow these steps: 

1. Use any text editor (such as Notepad) to open the System.ini file in the 
Windows folder. 
2. Locate the line that loads the Mh32bit.386 device driver. 
3. Place a semicolon (;) at the beginning of the line. 
4. Save and then close the System.ini file. 5.Restart Windows 95. 

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26: My DriveSpace 3-compressed slave drive does not boot after I 
made it my master drive. I get "invalid drive" error message. What 
is wrong?

Use the Sys command to transfer the system files to the "host" drive (the 
non-compressed drive, C drive *is* compressed/"invalid"). 

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27: I am adding a new Caviar drive but DriveSpace 3 is unable to 
decompress my existing Caviar drive. What should I do?

There is one small but vital INI file which needs to be corrected to reflect 
the new configuration. It is a hidden, read-only file called DBLSPACE.INI. It 
is located in the root directory of the host drive. Most likely, DBLSPACE.INI 
is still referring to the host drive as H: (or another label which is no longer 
valid since a new drive has been added to the system). As a result, DriveSpace 
3 looks for the host drive that is no longer there. Simply change the read-only 
and hidden attributes on DBLSPACE.INI, replace any reference to the old host 
drive with the new drive letter designation, save the file, restore the R and H 
attributes, and restart DriveSpace 3.

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28: How can I copy the contents of my old drive to my new drive and make the 
new drive the Master drive in Windows 95?

Disclaimer: Western Digital Corporation makes no warranty, implied or otherwise, 
regarding the reliability of the proceeding information. This document is provided, 
as is, solely for your information. To obtain product specifications and warranty 
information, please contact your system manufacturer.

One of the most frequently asked questions posed to Western Digital Technical 
Support is how to transfer all files from the old to the new drive and make it 
the boot drive in Windows 95. 

Here we have compiled a list of steps (that have been tested and recommended by 
many of our customers) that should allow you to copy your files over to your new 
drive, then make the new drive your primary or boot drive. 

NOTE: The following steps may not be effective in your system. Microsoft does 
not recommend the use of the following procedure, however, results as reported 
by many of our customers have been very positive. Western Digital makes no 
warranty, implied or otherwise, regarding the reliability of the proceeding 
information. This document is provided, as is, solely for your information. 
Please consult your system manual or system manufacturer for further details. 

First, install your drive as a slave/secondary drive to your existing hard drive. 
Be sure to jumper both of your drives properly. See Typical Hard Drive Installation 
for further information. 

Create a Boot diskette (Rescue disk) as follows: 

1. Double-click on My Computer
2. Double-click on Control Panel
3. Double-click Add/Remove Programs
4. Click the Startup Disk tab in the dialog box
5. Click Create Disk, and follow the instructions

Restart your computer in MS-DOS mode and using EZ-Drive, partition and format your 
drive. Please see Before You Begin Installing Your Hard Drive to determine whether 
or not you require the use of EZ-Drive. 

You may need to partition and format your drive manually if EZ-Drive is not needed. 

In either case, be sure to transfer the system files to your new drive using the SYS 
command. You can transfer the system files by opening a DOS session under Windows 
95 and type: 

sys d: 

Close the DOS window and double-click on My Computer again. Double-click on 
Control Panel and then System. Click on Performance tab and Virtual Memory button. 
Click on "Let me specify my own system memory setting" and disable virtual memory. 

Restart Windows 95 and on the Taskbar click on Start, Run and type: 

xcopy c:\*.* /e /h /k /r /c d: 

and click OK. This command line copies all your files to the new drive. If your 
existing drive is fairly large, this operation could take some time. Do not power 
down your system during this operation. 

Once this operation is completed, shut down Windows 95, turn off your PC, and 
change the jumper settings on your drive so that your new Caviar drive is the 
master/primary and the older drive is the slave/secondary drive. 

Place your boot diskette in the floppy drive and turn on the PC, edit the CMOS 
settings to reflect the change in master/slave drives, then continue booting with 
your start-up disk. 

At the A: prompt, type Fdisk and select option 2 to make the primary partition 
on your new disk drive the active partition, then exit Fdisk and reboot. 

Now, Windows 95 should boot from the new hard disk. It is also a good ideal to 
allow Windows 95 to determine your Virtual Memory settings. To do so, 
double-click on My Computer, then Control Panel and System icon. Click on 
Performance tab and Virtual Memory button then Click on "Let Windows specify my 
own system memory setting." 
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