Mosaddique - How to remove Dual-Boot

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Dual-Boot Removal Procedures ---------- Use at your own risk ---------- Updated: 19:47 26/02/04
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The procedures documented here show you how to:

1. KEEP Win9x and REMOVE WinXP - When Both use the same FAT Partition.
2. KEEP Win9x and REMOVE WinXP - When Both use Different FAT Partitions.
3. KEEP Win9x and REMOVE WinXP - When FAT used for Win9x and NTFS used for WinXP
4. KEEP WinXP and REMOVE Win9x
5. REMOVE WinXP - Uninstall WinXP from an NTFS System and install Win9x instead

A reinstall is NOT necessary.

Note - Throughout these procedures:

Win9x - Applies to Win95, Win9R2, Win98 or Win98SE. It also applies to WinME
WinXP - Also applies to Win2k and WinNT

Warning !!

Do not use with any DDO (Dynamic Disc Overlay) or hard disk-management software (such as
OnTrack Disk Manager or similar Disk Managers) that allow you to access a large hard disk.

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Background reading Information on dual boot removal
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Boot Control
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Under a Win9x and WinXP dual-boot system, boot control is from the first active partition
which is nearly always the C: drive. This needs to be:

Replaced if removing WinXP and keeping Win9x (SYS.COM is used), or
Altered if removing Win9x and keeping WinXP (Boot.ini must be edited).

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Bootfiles
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The bootfiles for all installed Windows are in the root of the active partition which is nearly
always C:. Many bootfiles have Hidden, Read-only, and System attributes.

WinXP has: Boot.ini, Bootsect.dos, Ntldr, Ntdetect.com and, if they exist, Ntbootdd.sys

WIN9x has: Io.sys, Msdos.sys, Command.com and, if they exist, Autoexec.bat and Config.sys.

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Win9x Boot Disk and WinXP CD
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You'll need the Win9x bootdisk if removing WinXP.

You'll need the WinXP installation CD, if removing Win9x, and/or if you wish to alter a
partition type, FAT or NTFS.

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Windows Folder
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All folder/files of each Windows are wherever you installed that Windows.
Typically :\WINNT for WinXP, and usually C:\Windows for Win9x.

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KEEP Win9x and REMOVE WinXP - When Both use the same FAT Partition.
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This procedure describes how to remove the Boot Loader to remove WinXP from a dual-boot system
with Win9x when they use the same FAT partition, and leave Win9x as the bootable OS.

The following steps apply only to PCs in which the boot drive (drive C:), and all other drives,
use the FAT file system, and the boot drive contains the Win9x bootfiles (the hidden Io.sys
and Msdos.sys; plus Command.com and, if they exist, Autoexec.bat & Config.sys).

Backup critical data on your hard disk.

1. Use the Win9x bootdisk to bootup the PC.
At the A: prompt, type
SYS C:
and then press ENTER.

The Sys command transfers control of the boot process to Win9x. You will see a System
transferred message. All future reboots should now start the Win9x.

2. Now delete these (some Hidden) bootfiles from the root folder:
C:\Boot.ini, Bootsect.dos, hiberfil.sys, ntbootdd.sys, Ntdetect.com, Ntldr, Pagefile.sys
(not all are always present).

3. Finally, delete the WinXP installation folder (typically C:\Winnt).

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KEEP Win9x and REMOVE WinXP - When Both use Different FAT Partitions.
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This procedure describes how to remove the Boot Loader to remove WinXP from a dual-boot system
with Win9x when they use the different FAT partition, and leave Win9x as the bootable OS.

The following steps apply only to PCs in which the boot drive (drive C:), and all other drives,
use the FAT file system, and the boot drive contains the Win9x bootfiles (the hidden Io.sys
and Msdos.sys, Command.com, and, if they exist, Autoexec.bat & Config.sys).

1. Backup critical data from the WinXP drive.

2. Use the Win9x bootdisk to bootup the PC.
At the A: prompt, type
SYS C:
and then press ENTER.

The Sys command transfers control of the boot process to Win9x. You will see a System
transferred message. All future reboots should now start the Win9x.

3. Finally delete these (some Hidden) bootfiles from the root folder:
C:\Boot.ini, Bootsect.dos, hiberfil.sys, ntbootdd.sys, Ntdetect.com, Ntldr, Pagefile.sys
(not all are always present).

4. You can now Format the WinXP drive, or, at least, delete its installation folder and
Program Files and other folders.

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KEEP Win9x and REMOVE WinXP - When FAT used for Win9x and NTFS used for WinXP.
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This is very similar to the previous procedure, except that you can first convert the NTFS
partition(s) to the FAT file system. This can be achieved by using the WinXP installation CD
before transferring boot control to Win9x.

There's total loss of data on the NTFS partition(s).

1. Use the WinXP CD to bootup.

2. Select fresh install when asked to repair, or fresh install a new, WinXP.

3. Remove the WinXp NTFS partition(s) when Setup asks you to select a partition,

4. Create a new FAT partition(s) to replace the removed NTFS partition(s).

5. Exit the Setup program (F3) without installing.

6. Use the Win9x bootdisk to bootup the PC.

At the A: prompt, type
SYS C:
and then press ENTER.

The Sys command transfers control of the boot process to Win9x. You should see a System
transferred message. All future reboots should now start the Win9x.

7. Now delete these (some Hidden) bootfiles from the root folder:
C:\Boot.ini, Bootsect.dos, hiberfil.sys, ntbootdd.sys, Ntdetect.com, Ntldr, Pagefile.sys
(not all are always present).

The new FAT has destroyed the WinXP installation, and associated Program Files and folders.

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KEEP WinXP and REMOVE Win9x.
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This procedure describes how to alter the Boot Loader to remove Win9x from a dual-boot
installation with WinXP, and leave WinXP as the bootable OS.

1. Uninstall all Win9x software if both OSs are on same drive.

2. Boot to WinXP, and backup C:\Boot.ini (it's a Read-only file).

3. Change the file attributes for C:\Boot.ini to make it editable.
Open a DOS Prompt Window and type in attrib -r -h -s C:\Boot.ini

4. Open C:\Boot.ini in Notepad.

5. Delete the line(s) that refer to Win9x.

Make sure the Default= line points to WinXP not to Win9x.

6. Set timeout=0 so the system boots directly into WinXP (no boot menu will appear).

7. Save & Exit.

8. Restore the file attributes for C:\Boot.ini
Open a DOS Prompt Window and type in attrib +r +h +s C:\Boot.ini

You'll finish with a C:\Boot.ini that looks something like this:

[Boot Loader]
timeout=0
Default=multi(0)disk(0)rdisk(0)partition(1)\WINNT
[Operating Systems]
multi(0)disk(0)rdisk(0)partition(1)\WINNT="Microsoft Windows XP Professional" /fastdetect

(note: there's no reference to a Win9x).

9. You can now delete the bootfiles for Win9x: C:\Io.sys and Msdos.sys (Hidden files), plus
Command.com and, if present, Autoexec.bat and Config.sys.

10. Finally, delete the Win9x folder (typically C:\Windows), and Program Files (if not shared).

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REMOVE WinXP - Uninstall WinXP from an NTFS System.
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This procedure describes how to totally remove WinXP on an NTFS system so as to enable you to
install Win9x (alone, to a new FAT C: drive).

The existence of the active NTFS drive is preventing you from installing Win9x.

Caution: All data on the NTFS drive will be destroyed.

1. Save all appropriate data, settings, passwords, etc.

2. Bootup to true DOS with a Win9x bootdisk, and type in

3. a:\fdisk /mbr
This will create a new boot sector (DOS, FAT), destroying the existing NTFS.

4. The disk can now be formatted (a:\format c: /s).

5. You can use fdisk /status to identify your partitions.

6. A Win9x can then be installed in the standard manner.

Caution: The /MBR switch is an 'undocumented' FDisk switch, However, even Microsoft suggests
using it on some of the pages at their Website.

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End of Removal Procedures.
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