View Full Version : FAQ #44 Multi-booting a Windows System

25-08-2004, 11:22 PM
FAQ #44 Multi-booting a Windows System

Originally written by Graham Petrie -- Last Updated: 31/10/2002


There are many reasons why you may want to run more than one copy of windows on your PC. You may want to keep your old OS whilst you try out a new one (like Windows XP), or you may have compatibility issues with old software on your new OS, and wish to retain an old one to run this software on. Also, you may want to test programs you have written on different versions of windows before you release it. I will assume that you have your own reasons, and now wish to perform the task of turning your PC into a multi-boot system. This FAQ will deal with the multi-booting of two or more Windows Operating Systems. Multi-booting with Linux will be covered in another FAQ.

This article will cover multi-booting any of the following Operating Systems:

MS-DOS Windows 95/98/ME/2000/NT/XP

What You Need

The first step is to acquire the installation disks (and boot disks for MS-DOS or Windows 95/98) of the Operating Systems you wish to install on your PC.

You will also need some software for partitioning your hard-drive. You could use the DOS function 'fdisk' or you could obtain a boot disk for a program such as Partition Magic. If you already have a Windows Operating System installed on your system, you could use a program such as Partition Magic to partition your drive from a Windows interface.

Backing Up

Now you have what you need to get started, there is some preparation you must do before you start partitioning your drive. If you are starting with a blank hard-drive, you can miss this step.

It is possible to create a multi-boot system whilst retaining an existing Operating System, but as I believe that a multi-boot system should be built on a clean slate, I will not be covering this possibility. You can read between the lines if you like, and with a little luck, you may get away with it, but I do not recommend it.

So, the first step in preparing your hard-drive is to back-up any important information currently on the drive to another drive, or to a removable media such as floppy disk or CD-R. More detailed information on backing-up can be found in another article. I will just assume you have some-how managed to get it done. Don’t forget any updated drivers or Windows updates. You may also wish to find updated drivers for all your hardware for each of the Operating Systems you wish to install whilst you still have a working system, to make things easier later on. Back these up with you other critical files.

Now you have all your data safely backed up, it is time to partition and format your hard-drive in preparation of the impending install.

Preparing Your Hard-drive

Before you rush in and slice up your hard-drive, there are several things to consider.

How big is the drive? Is it big enough for all the Operating Systems you wish to install, and your data? You will find it difficult to dual-boot Windows XP and Windows 98, and store all your files on a 4GB hard-drive.

How many Operating Systems do you want to boot? This will determine the minimum number of partitions you need.

What file system do you want to use for each Operating System (OS)? There are several to choose from, which are discussed in a different article (I will go over the basics here).

You should draw a diagram to help you figure out how many partitions you need, and how much space to allocate each of them.

As an example throughout this article I will use a 20GB hard-drive and install three Operating Systems on it (MS-DOS, Windows 98 and Windows XP).

For this set-up we require a minimum of three partitions (one for each OS). I am going to use four (the extra one will be for files only). For detailed information about partitioning, see a separate article - I will go over the basics here. I am creating a separate partition for data so that I can easily reformat on of my OS partitions at a later date without losing my critical data. The following table shows the layout of my partitioned drive:

Partition 1: MS-DOS File System: FAT Partition Type: Primary Partition Size (GB): 2
Partition 2: Windows 98 File System: FAT32 Partition Type: Primary Partition Size (GB): 3
Partition 3: Windows XP File System: NTFS Partition Type: Primary Partition Size (GB): 5
Partition 4: None (Data) File System: FAT32 Partition Type: Logical Partition Size (GB): 10

I have given each OS a decent sized partition to allow for flexibility with programs, and to ensure there will always be plenty of space. You could get away with partitions up to half as big before you ran into major difficulties.

If you wish to boot MS-DOS with Windows NT, the DOS partition must be smaller than 2GB to allow part of the NT partition to be within the first 2GB of the disk. This is due to boot limitations of Windows NT, and doesn’t apply to the other OSs. Note: A bootable Windows NT partition must also be smaller than 7.8GB.

There are three possible types of partition: Primary, Logical and Extended. An OS MUST be installed on a primary partition. Windows Master Boot Records (MBR) only support up to four primary partitions on any physical drive, so you are effectively limited to four OSs on any one hard-drive.

Data may be placed in a logical partition. Logical partitions are located within an extended partition. In this case, there are three primary partitions, and one extended partition. There is one logical partition within the extended partition which takes up all of the available space in the extended partition.

The file system of each partition must be considered. MS-DOS and Windows 3.1/95 must be installed on a FAT partition. Windows 98/ME cannot “see” NTFS, and Windows NT/2000/XP can “see” all Microsoft file systems (FAT, FAT32, and NTFS). Note: Newer versions of Windows 95 can also read FAT32 partitions.

Thus, I have installed DOS on a FAT partition, Windows 98 on a FAT32 partition, XP on an NTFS partition, and made the data partition a FAT32 partition so that it can be read by both Windows 98 and XP.

For this you will need a program like partition magic or Ranish (http://www.ranish.com) (Free). There are also other free DOS-based partitioning programs available as outlined in the last section of this FAQ.

The order of the partitions should be the same as the order of installation of the OSs for ease. The order of installation of the OSs is very important if you want a workable PC. If you install DOS after you have installed XP, DOS will overwrite XP’s boot info, and your PC won’t know XP is there.

The order for install Operating Systems is as follows (cross out those OSs you don’t wish to install, and you will be left with the order to install your specific set of OSs):

Windows 3.1
Windows NT
Windows 95
Windows 98
Windows ME
Windows 2000
Windows XP

The general rule is that the newer the OS, the later it is in the install list.

Note: Installing Operating Systems in a different order than this is covered in a section at the end of this FAQ. This is only recommended for advanced users

Now you have a clean, partitioned and formatted hard-drive, it is time to begin installation of your OSs. The first OS should be installed onto C:\.

Installing MS-DOS (NB: If you don’t want DOS, but are installing Windows 3.1/95/98, you still need to do this step.)

You can now install MS-DOS. Insert the first MS-DOS set-up disk, and reboot the machine. Follow the instructions and install DOS onto C:\. (You will be prompted for the other DOS set-up disks. At the end, remove the last disk and reboot the machine. You will boot into DOS, and see a C:\prompt on the screen.

Instructions for other OSs follow.

Installing Windows NT/ME/2000/XP

Insert the Windows set-up disk and reboot your machine. Follow the on-screen instructions.

During the installation process, you will be asked to select the partition to install to. Select the partition you are installing Windows to. You can also format the partition at this stage if you have not yet done so.

Once installation has finished, reboot, and you will boot into Windows graphical interface. From there you can set-up Windows as you wish, or reboot to DOS. You may want to spend some time installing drivers for Windows and getting everything working before you move onto the next OS.

Installing Windows 95/98/ME

Boot into NT if running NT, or DOS if not. If you do not want a separate DOS partition, that is fine, as Windows 98 is installed on top of DOS anyway. In fact, if you want to have DOS, and also want any of Windows 3.1/95/98/ME, then you do not need a separate partition as all these OSs are built on DOS, and you can boot to DOS using a shutdown command, or boot disk.

Once in NT or DOS, navigate to the CD directory and run setup.exe (If in DOS, copy the entire contents of the CD to a new directory called C:\setup first, and run setup.exe from C:\setup).

You can then follow the on screen instructions, and finally reboot. You can now install a video driver if necessary, and boot to Windows. From there you can set-up Windows as you wish, or reboot to DOS. You may want to spend some time installing drivers for Windows and getting everything working before you move onto the next OS.

Configuring Boot Options

Depending on which OSs you have installed you will see a different boot loader interface on boot-up. If you only have older OSs like DOS, or Windows 3.1/95/98/NT you may have to hold F8 or a similar button at start-up to get to the boot options, or you may need a boot floppy. If you have installed a newer OS like XP, the boot options menu appears automatically on start-up. Either way, the boot options are defined in boot.ini which can be found in C:\ or on your boot floppy. This file contains text which tells your PC what to do on start-up. Here is a copy of the boot.ini file for the example system used in this article:

timeout=30 default=multi(0)disk(0)rdisk(0)partition(3)\WINDOW SXP
[operating systems] multi(0)disk(0)rdisk(0)partition(1)\DOS="Microsoft DOS 6.2"
multi(0)disk(0)rdisk(0)partition(2)\WINDOWS98="Microso t Windows 98"
multi(0)disk(0)rdisk(0)partition(3)\WINDOWSXP="Microso t Windows XP Professional" /fastdetect


timeout = the number of seconds the boot-menu is displayed before the default option is loaded.
default = the default OS which is loaded if no choices are made before the menu times out.
[operating systems] = This is a list of all the operating systems available on the boot-menu. The words in the speech marks “” are what is displayed in the boot-menu for each OS.

You can modify this file to set whichever options you wish.

In Windows XP, there is an easier way to alter the options.

Right-click My Computer, or press Windows+Pause/Break.

Click on the ‘Advanced’ tab in the system properties window. Click ‘Start-up and Recovery’. A new window opens with controls for all the options listed above.

The other option is a third-party boot-manager like XOSL (http://www.xosl.org/) which takes over when you boot and allows you to select the OS you wish to load.

And there you have it! A perfect multi-boot system!

You should now use a product like PowerQuest’s Drive Image, or Norton’s Ghost to image your new installation so you can restore it easily if things ever go wrong. Imaging is covered in more depth in another FAQ.


PowerQuest (http://www.powerquest.com)
PC911 - How-To Multiboot article (http://www.pcnineoneone.com/howto/multiboot1.html) (Contains some more detailed instructions on OS installation, and how to add or remove OSs after you have already set-up a multi-boot OS).

MS Links to KB Articles - Submitted by Merlin

FAT16 File System (http://support.microsoft.com/default.aspx?scid=kb en-us;Q118335)
FAT32 File System (http://support.microsoft.com/default.aspx?scid=kb en-us;Q154997)
NTFS File System (http://support.microsoft.com/default.aspx?scid=kb en-us;Q100108)
Requirements to Boot Previous Operating System (http://support.microsoft.com/default.aspx?scid=kb en-us;Q114841)

Installing OSs in a Different Order - Submitted by Merlin

The information below is recommended for use by advanced users only. It details how to install the various OSs in your multiboot machine in a different order than outlined above. This part of the FAQ was submitted by Merlin in another thread and full credit goes to him for his contribution.

Booting to multiple primary partitions requires the creation of up to the maximum of 4 primary partitions per hard drive.

An inbuilt limitation of Windows operating systems using FAT format (namely any MS OS from DOS through to Me) is that they can only recognise one primary partition per hard drive unlike the NT based operating systems which can recognise up to 4 per drive. (Why only 4? Limitation of space used to record the partitioning information at the end of the master boot record).

A second limitation is MS FDISK which will only create one primary partition per hard drive.

To overcome these two limitations, a third party disk partitioning program is required - such as Partition Magic, though my preferences are either of the two DOS based EFDISK and AEFDISK programs.

Whatever is used, the objective is to create up to 4 primary partitions and to then "hide" all but one which is set active or bootable. By "hiding" the additional primary partitions the Windows operating system which is being installed can only "see" one primary partition - the one it is being installed into and thus no partition conflicts are created. (Leave two primary partitions "unhidden" and watch what happens when Windows - or DOS - is installed).

Once DOS or Windows is installed on the first primary partition, use the third party disk partitioning program to "hide" that partition, "unhide" another which is then set active or bootable.

If the active partition is "hidden", an error message or a flashing cursor is all that will be seen when attempting to access the bootable partition. Active partitions must be "unhidden".

Install a second Windows operating system in the second primary partition and proceed with the remaining partitions.

An example of four operating systems on the same hard drive could be:

Primary partition 1 - DOS 6.22
Primary partition 2 - Windows 98
Primary partition 3 - Windows 2000 Professional
Primary partition 4 - Windows XP Professional
Primary partition 1 - Windows 98
Primary partition 2 - Windows 2000 Professional
Primary partition 3 - Windows XP Professional
Primary partition 4 - Linux Red Hat 8 (check the installation instructions before creating partitions for Linux OS)

The last major limitation that MS operating systems have is that the system files for the earlier FAT based operating systems (up to Windows 98) have to be within the first 2 gigabytes of the hard drive. Usually this is not a major issue since each MS operating systems were designed to exist by itself on each hard drive. However it is something to be aware of when creating multiple primary partitions.

To access each operating system use a third party boot manager. This ensures that each operating system is kept independent and inaccessible from each other.

Several boot managers exist and all have their pros and cons. Boot Magic provides a Windows like feel complete with mouse while others are reminiscent of DOS. Usually most boot managers are installed on the first primary partition and most manufacturers recommend it be formatted with FAT16 or 32 for ease of troubleshooting. Check the installation instructions for configuration.

In the case of reinstalling an operating system, disable the boot manager and use the disk partitioning program to "hide" all the partitions except the problem one which is set active or bootable. Format and/or install as usual. Use the disk partitioning program to "unhide" the partition containing the boot manager (set it active and also "hide" the other partitions), restart and enable the boot manager.


Original FAQ available from here (http://pressf1.pcworld.co.nz/thread.jsp?forum=1&thread=21527&message=56764&q=FAQ+%232#56764).