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Dual-Boot or Multi-Boot:

Install Win NT (FAT/NTFS) on a Win9x system (FAT)

Last reviewed: March 2004

How to dual-boot Windows NT when any Windows 9x using FAT16 is already installed on your PC. A dual-boot is created. No third-party boot utility is used.

If you wish to install NT on a Win 9x system that uses FAT32, go to Install Win NT (NTFS) on any Win9x (FAT32).

This is reliable and safe, easy and painless. No loss of data occurs. It's even suggested by Microsoft!

Boot up Win9x.
Install NT as a NEW installation on its own partition.
The Win NT partition can use FAT or NTFS. It can not use FAT32. And DO NOT convert the C: drive to NTFS.

The Boot Loader menu will then allow you to boot to either Win NT or the Win9x/Me.

Please read Dual-Boot Win9x+XP/2K/NT for an overview.


Installing a Windows NT on a Windows 9x FAT system is quite easy.

Already installed: Win9x using FAT. You want to add: Win NT.

You just install the Win NT (to its own drive/partition). It's usually that easy!
Then, during boot up, a menu pops up and you can select which Windows to boot, or allow the default to boot. But read on . . .

Windows NT designed to operate with other operating systems. The Win NT installation will SAVE the current Win9x boot sector in the file c:\BOOTSECT.DOS. and will then create its own boot sector on C:. If the Win9x is selected from the Boot Loader Menu then Bootsect.dos is used - this runs IO.SYS & MSDOS.SYS which load the Win9x.

Your current C: is a FAT16 ('FAT') partition. During the NT installation you'll have to choose a FAT file system, or NTFS, for its installation drive. Windows NT can boot from a FAT drive (C:) and then operate under NTFS or FAT from its own partition.

If you choose FAT for Win NT, you will have access to all files on all FAT drives (but you will lose some of the benefits of the NTFS system, mainly security related).

If you choose NTFS for Win NT, then, while in Win9x, you will lose access to the files stored on the NTFS partitions, but you will retain all the benefits of the NTFS. Do NOT convert the C: drive to NTFS.

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One possible difficulty is that you should have two logical drives (or hard disks).

Ignore Microsoft's suggestion (Q217210) to install XP/2K/NT on the same partition as Win9x.

Win NT and a Win9x should not be installed on the same logical drive. Installing different OSs on a single partition may cause problems running those OSs. A single Hard Drive is perfectly fine, but it should be partitioned to at least C: and D:. At a minimum the items in Program Files, including those Common/Shared components, will cause conflicts. IE and Outlook Express are likely to break, and other applications are also at risk.

C: must continue to use a FAT file system or the Win9x will become unbootable.
If using FAT for NT then the NT partition can not exceed 2GB.
If using NTFS for NT then its partition can be up to 7.8 GB (you need SP5 for greater than 7.8GB).

To prevent the accidental deletion of an NTFS logical drive, you should create all logical drives within Fdisk and delete them from Disk Administrator. After NT is installed, you should avoid formatting logical drives as NTFS within the extended partition.

Microsoft says it's best to "install Windows NT on a Primary partition". However Win9x prefers just one Primary per hard disk. For greater safety, install NT on the Primary partition of a second hard disk if you have one.

Click HERE to learn how to install another hard disk without changing current drive letters.

If you have a single Hard Disk with a single partition (a C: drive, but no D: except for a CD or DVD drive), it's recommended that you Fdisk & Format (with loss of data!).
You can use utilities like PartitionMagic ($), or BootIT ($), or Partition Manager (165KB, freeware) to repartition without loss of data.

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It's worthwhile emphasizing the importance of FAT with a Win9x.

Windows 9x can not boot from an NTFS partition.
Windows NT can not boot from a FAT32 partition - but read NT(NTFS) on 9x (FAT32)
Both Win 9x and NT can boot from a FAT partition (the C: drive).

There are four important ingredients to a Win9x installation:
1. PC system partition type (C: must always use FAT or FAT32)
2. Win9x boot files (always on C:)
3. Win9x boot partition (usually C: but can be elsewhere using same FAT type as C:).
4. Win9x boot partition must begin before 2 GB (Win95,a) or 8 GB from physical start of disk
    - 98+ can boot from beyond the 8 GB boundary if the system supports INT13 Extensions.

Therefore, in this dual-boot:

• If Win9x is installed on C:, then you just need a second partition, or a second disk.
• If Win9x is not on C:, then you can install NT on C: and use FAT.

• If you have only one partition then you must:
     start fresh using the #2 Reinstall method (data is lost when you repartition),
     or add a second hard disk (no loss of data),
     or use third-party partition utility to create more partitions (no loss of data).

Adding a disk will alter drive letter allocations if current disk has more than one partition!

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EXAMPLES: Install Win NT on Win 9x (FAT)

Examples of Partitions & File System types that can be used in this Dual-Boot.
A second hard disk (Disk 1) is helpful, but it is partitions and file system types that count most.

Example 1: 
Disk 0 C: Win9x FAT  Primary  (PC system partition;  1.7 GB max.) 
Disk 1 D: WinNT FAT  Primary  (both Windows can read both drives) 
Example 2: 
Disk 0 C: Win9x FAT  Primary  (PC system partition;  1.7 GB max.) 
Disk 0 D: WinNT NTFS Logical  (NT can read both. Win9x can't read D:) 
Example 3: 
Disk 0 C: WinNT FAT  Primary  (PC system partition;  1.7 GB max.) 
Disk 1 D: Win9x FAT  Primary  (both Windows can read all drives) 
Disk 1 E: No WinFAT  Logical  (data shared by both Wins) 
Example 4: 
Disk 0 C: No WinFAT  Primary  (PC system partition;  1.7 GB max.) 
Disk 0 E: WinNT NTFS Logical  (NT can read all drives) 
Disk 1 D: Win9x FAT  Primary  (Win9x can read only C: & D:) 
Disk 1 F: No WinNTFS Logical  (NT data) 
When C: is not the OS Boot Partition:
The OS boot partition must begin before a certain distance from the start of the hard disk to be bootable. The OS boot partition for DOS, FAT, NT must begin before 2 GB from the start of the hard disk. The boot partition for other Windows must begin before 8 GB from start of disk. If your PC supports INT13 Extensions, then 98+, XP, 2000 can boot from beyond 7.8 GB.

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Remember, you will need to repartition or add a hard disk:
  • if you have only one partition (only a C: drive).
Remember, you will need to format your C: drive:
  • if that PC system partition is not formatted correctly (C: must use FAT).

Note: PartitionMagic 5.0 was freeware with PC Magazine in June 2002. Get a copy!

Windows NT
Win NT4 uses an NTFS incompatible WinXP/2000's NTFS unless updated with SP 5(+).
That update should first be installed if XP/2000 is to be dual-boot with NT4.

Uninstalling Win 9x.
Never 'Uninstall' Win Me from a dual-boot: You should edit Win Me out of Boot.ini, and manually delete all Me's folders and files. Win Me's Uninstall.exe restores a backup copy of the Me partition information (stored in c:\Suhdlog.dat) even if the partition information has changed.
Uninstalling Win 98 Upgraded from Win95 in a Dual-Boot: Uninstalling the Win98 upgrade may delete boot.ini - save/recreate it. The uninstall also deletes C:\Bootsect.dos - save it first!

"Do you wish to enable large disk support (Y/N)?"
When Fdisk asks you this, it wants to know if you wish to use the FAT32 file system.

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Checklist for Adding a NT on a Win9x FAT system:

1. Hardware drivers compatible with next Windows (mainboard, hard disk, video, ..)
    For those in Windows, check list shown in \Drivers\ on its CD.
2. Win9x already installed on a C: partition that uses FAT.
3. At least two partitions.
4. C: drive must use FAT ('FAT' means FAT16).
    Right-click C: drive in My Computer, and click Properties. Look at File system:.
5. All Hardware, & drivers, compatible with the Win9x to be fully installed.
6. Installation CD for the Win9x - it may be needed, sometime.
7. Installation CD for Win NT - obviously!
8. Backup of current Win9x boot files.
9. Win9x Boot disk (that contains SYS.COM and gives CD access) - essential.
10. Floppies - for Win NT Setup boot disks & Repair disks set - essential.
11. Make sure your system is suitable for running the new OS.
12. Read and save the REPAIR DUAL-BOOT page BEFORE you start.

Update NT with its SP 5(+) to use a large NTFS drive.

Create Floppies.
To create NT's Setup Boot Disks (3) run winnt32 /o from the CD.
To create NT's Emergency Repair Disk (1), ERD, run rdisk.exe /s
To create Win9x's Startup Disk go to Control Panel > Add/Remove Programs > Startup Disk.


How to install Windows NT on a Win9x system that uses FAT:
First get floppies to make a Win NT Setup boot disk set (3), and ERD (1).

1. Switch OFF anti-viral software (& check in BIOS/CMOS also).
2. Routinely backup the current boot files, and important data.
3. Create a Win9x Boot disk (that contains SYS.COM) - essential.

4. Boot up Win9x, and insert your NT CD (run x:\I386\WINNT.EXE if no autorun).
5. Install Win NT using the Advanced option in Setup.
      Make sure it installs as a new installation - not as an upgrade.
      Make sure the correct target drive is selected as the installation drive.
      Make sure Win NT uses a name different from the Win95 name.
      Do not convert the C: drive to NTFS or FAT32.
      Use FAT or NTFS for its installation (system) partition
      (Win9x will not be able to read the NT partition if you use NTFS).
6. Create Win NT's ERD (run Rdisk.exe /s), and boot disks - ESSENTIAL
    WINNT32 and MAKEBT32 (\Boot disk folder on CD) are used to create boot disks.
7. Finally, always create a new Rescue Boot Disk when a new dual-boot is successful!

Win NT controls the boot up. A Reboot brings up its Boot Loader menu and you can select Win NT or Win9x as the next Windows to boot (if not, read Repair a Dual-boot).

Note: In an emergency any Win9x Startup Disk (with CD support) can be used for running a NT CD (boot up with it and run WINNT.EXE from the I386 folder of your NT CD).

Note: If rebooting for hardware installation, be sure you select the correct OS!

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The system boot files for each Windows will be on its own PC system partition..

• When using NTFS for NT then the NT partition can be larger than 2GB (you need SP5 for greater than 7.8GB).

• You should try to install NT on a Primary partition, preferable on a different hard disk if you can.

• Win9x does not like more than one Primary partition per hard disk. However, Win9x can not 'see' the NTFS partition in a NT (NTFS) + Win9x dual-boot!

• You can download a free FAT32 utility from SysInternals to read data on your FAT32 partition. For a small charge, the full version lets you read from and write to FAT32 partitions.

• You must install SP5, or later, for NT4.0 if you intend to also install Windows XP or 2000. This update makes NT's NTFS compatible with the NTFS used by XP and 2000.

• From Microsoft: If you are installing Windows NT to an IDE drive that is larger than 7.8 GB, you need to install Windows NT 4.0 SP 4 (SP5), or later, immediately after Setup is finished. This enables NT to view large IDE drives correctly.

• From Microsoft: To prevent the accidental deletion of an NTFS logical drive, you should create all logical drives within Fdisk and delete them from Disk Administrator

• From Microsoft: After NT is installed, you should avoid formatting logical drives as NTFS within the extended partition.

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Specifying the Default OS to Boot, and the Boot Menu delay (the Timeout)

When you have established Dual-Booting, you will want to set which OS boots by default.

You can set the default OS (and the timeout) that you want via Control Panel.

1. Boot to the Win NT.

2. Go to Start > Control Panel > System > Advanced tab

3. Under Startup and Recovery, click Settings.

4. Under System startup, in the Default operating system list, click the OS that you want to start when you turn on, or restart, your computer.

5. Also select the Display list of operating systems for check box, and then type the number of seconds for which you want the list displayed before the default OS starts automatically.

You can also edit the boot options file (click Edit). Be careful of typing errors if modifying the boot options file (Boot.ini), because doing so may make your computer unusable.

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NEVER dual-boot without your personal safety net - a BOOT DISK for XP/2K/NT.
If stuck, use a Win9x Startup Disk (CD support), and run WINNT.EXE from I386 folder on CD.

RESCUE BOOT DISK for when XP, 2K, NT will not boot - ESSENTIAL, 1 floppy
   Create a bootable floppy to get XP/2K/NT running even if the boot record,
   or boot files, are ever a problem. Write-protect and keep it safe.
      Format a floppy with that XP, 2K, or NT. It must be a full XP/2K/NT format.
      Alter file Attributes (Attrib -r -s -h) of these files in root of C: (PC system partition)
      Boot.ini, NTLDR,, and Bootsect.dos & Ntbootdd.sys (if present)
      (plus Arcldr.exe & Arcsetup.exe - for Windows 2K) and copy them to the floppy.
      Write-protect the floppy. Then restore original Attributes to the files on C:.
      Read the Rescue Boot Disk page for fuller details, plus a much improved Rescue disk.
Use the CD: If you have a Bootable installation CD you should check if your BIOS
   supports booting from it. This is hugely convenient, but still make the floppy.
ERD XP, 2K, NT: Emergency Repair Disk - repair key Registry entries and partition geometry
2K/NT Setup Boot Disks: (4 floppies for 2K, or 3 for NT)
   Use WINNT32 and MAKEBT32 from 2K/NT (Boot disk folder on CD).
   Use WINNT and MAKEBOOT from a non-2K/NT system (such as Win9x).
XP Setup Boot Disks: (6 floppies)
   Read the Microsoft page How to obtain Windows XP Setup boot disks.
   It provides free downloads that create setup boot floppies for all versions of Windows XP.
   Each download is specific to each XP version (Home/Pro; original/SP1/SP2).
Win9x/Me Startup Disk:
   (95+) From a Windows: Control Panel > Add/Remove Programs > Startup Disk tab.
   (98+) From true MS-DOS: Go to the Command folder in Windows, and type Bootdisk.
   Windows 95 Startup Disks do not have CD support (add your CD-ROM driver).
   You can download free Win9x/Me boot disks from (IDE CDrom Drivers Included).

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Please remember that you alone are responsible for the consequences of any changes you make to your computer hardware or software.

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