to Windows Dual Boot
At one time, there was only Windows and
only one Windows, Windows v3. Now there are Windows, plural:
Windows 95, Windows 98, Windows NT, Windows 2000, and Windows
Me. What's more, the possibility exists that you, as a power
user, have more than one copy of Windows -- or more
than one type of Windows -- on one machine.
Having multiple installations of Windows on
one computer is called dual booting or multiple booting. Windows
NT and 2000 are designed to be installed in conjunction with
other operating systems, especially Windows 95/98/Me. Windows
95/98/Me are not: When you install them on a PC, they want to be
the only OS on that PC.
Is there any way around this? Yes; in fact,
there are many possibilities. This article will step you through
how to get the various versions of Windows to coexist with each
other on the same PC. Over the years, Windows has grown slightly
more tolerant of having more than one installation of itself in
a given PC -- especially NT and 2000 --
but a number of scenarios aren't supported at all by Microsoft
and require a little coaxing or, in some cases, trickery.
You can take several paths to achieve
multiple booting. These depend on what's already installed in
your computer, how many hard drives and partitions you have, and
whether or not you're amenable to (or capable of) using
third-party programs to control boot choices. If your machine is
sufficiently powerful enough (500MHz or better and at least
128MB of RAM), you also have the option of using an emulation
system such as VMware to run your other OSes.
First, you need to verify which OS you're
currently running, and which OS you want to add to your system.
If you're adding Windows 95, 98, or Me to a machine running
Windows 2000 or Windows NT, that's the most complex scenario.
Because it's also the scenario about which we've received the
most correspondence from our readers, we'll address it first.
Adding Win NT or 2K to a machine running
either Windows 95, 98, or Me is actually much easier, because
both NT and 2K are designed to coexist to a high degree with
other operating systems. Some pitfalls may be in store, but
we'll cover them in the following pages.
95/98/Me on a NT/2000 PC
Installing Windows 95, 98,
or Me on a Windows NT system is probably the most difficult of
the scenarios listed here. The reason is fairly simple: Windows
95/98/Me wants to be the only OS on a given computer, and will
take steps to insure that nothing else can boot up.
If you have Windows NT already installed on
the computer (on a FAT partition), for example, you'll get a
warning during the Win95/98/Me installation process about the
presence of NT system files. If you have an NTFS partition,
Win95/98/Me will report it as being damaged and won't let you do
anything about this except abort the installation, since it
doesn't let you interactively repartition your disk during
If you have NT/2K on a FAT partition and
install Win95/98/Me on it anyway, any NT/2K boot files will be
erased, and the boot sector will be replaced with a Win95/98/Me
edition. Win NT/2K, however, has repair tools to address this
problem, which we'll discuss in detail later.
Here are the steps for adding a Win95/98/Me
installation to a Windows NT machine.
1. Ensure your NT PC has
Service Pack 6a.
Windows NT, in an out-of-the-box installation, has problems that
can cause serious disk corruption if you're using a drive larger
than 2GB (and who isn't these days?). Before doing anything else
at all, make sure you have patched the system with the latest
Windows NT Service Pack plus whatever hotfixes are relevant to
your computer. With Windows 2000, you can patch with Service
Pack 1, but it's not required, since it comes 95/98/Me-aware out
of the box.
2. Make a Windows NT/Windows 2000 repair
Repair disks in Windows NT/2K are floppies, created with a
system utility, that contain copies of key Registry entries as
well as a description of the partition geometry of the disk. If
either of those things gets damaged, you can rebuild them to an
extent. A repair disk is one of those underrated Win NT/2K
features that can often save you when you least expect it. If
you make a mistake during this process, you won't regret having
To build a repair disk in Windows NT, use
the RDISK.EXE command-line utility. Just run it and follow the
prompts. In Windows 2000, run the Backup utility and click the
Emergency Repair Disk button on the Welcome tab.
3. Prepare a FAT partition.
Windows 9x can't install onto anything other than a FAT or FAT32
partition. FAT, also referred to as FAT16, is the original
partition format used by DOS and, later, Windows 95. Windows 98
introduced FAT32, a revised version of FAT that could support
bigger partition sizes and was more reliable. But NT supports
only FAT, so you need to have a FAT partition with enough free
space for Windows 9x to be installed. FAT32 cannot be read or
written by a Windows NT machine.
To be scrupulously honest, it's possible to
have Windows NT read and write FAT32 partitions with a
third-party utility. However, if you want your system to be as
reliable as possible, we don't recommend using such a method.
The partition in question
doesn't have to be the primary boot partition in the computer,
but it must be a DOS-accessible partition for the installation
to succeed, and the bootable partition in the system must be
FAT. If there's no such spare partition in the system, you will
have to make one using a third-party tool such as PartitionMagic.
Windows doesn't support the selective editing of partitions and
neither does Windows NT, for that matter!
Only FAT16 or FAT32
partitions, not NTFS, can support a Windows 95/98/Me
installation. FAT16 provides the best
cross-compatibility with other operating systems.
You can use the same partition that holds
Windows NT itself, but we don't recommend it for two reasons:
1) You must not use the same directory name
for both operating systems. This actually varies by default: NT
installs in \WINNT, and Windows 9x installs in \WINDOWS.
However, if NT were installed in \WINDOWS for whatever reason,
it would create problems, and some applications stupidly expect
Windows to be installed in \WINDOWS and nowhere else.
2) The \Program Files directory is used by
both operating systems to hold apps that are installed by
default -- everything from IE to Solitaire. Because some of
these apps are OS-specific -- some are specifically
for NT that aren't for 9x and vice versa -- you may
wind up breaking one OS's default app set if you install it on
top of the other. This alone is reason not to install both OSes
on the same partition, since the \Program Files directory can't
be easily redirected during the install process.
Preparing a partition in Windows NT is done
through the Disk Administrator utility. Right-click in the
listed free space on a drive and choose Create; right-click in
the same space again and choose Commit Changes Now; then Format.
4. Create a Windows 9x boot
Sure, you're always supposed to have a boot disk handy, but more
often than not, you don't. For dual booting, you'll definitely
need a Windows 9x boot floppy disk. Find a PC running
Win9x and a blank floppy disk. You'll be preparing a
bootable floppy disk that will have nothing on it save the
command-line version of Windows, which is basically, DOS. To do
this, boot Win 95/98/Me and run the following command-line
operation: FORMAT A: /S with a blank floppy in drive A:.
From the \Windows\Command directory, copy the SYS command to
the A: disk as well.
NOTE: Don't mix and match OSes here. If you're
installing Windows 95, don't use a Windows 98-prepared boot
disk. It won't work. Windows 95, 98, and Me all practice pretty
stern revision control over their own internal files and
5. Copy Win98 installation files onto the hard drive.
With Win NT running, insert the Windows 98 CD-ROM and copy the
contents of the \SETUP folder onto an available FAT partition.
Use the same folder name unless a folder named SETUP is already
there. If it is, try a folder name such as NewSetup.
6. Boot with the floppy; then run the install files from
Put the prepared boot floppy in your A: drive and reboot. Once
you've booted into command-line Windows (DOS mode), type
"SYS C:" to transfer the boot files. The command
should return the statement "System transferred."
Switch to the \SETUP folder you copied over and run SETUP.EXE.
Windows Setup should begin the install process.
As we mentioned before, you're going to get a warning about
Windows NT system files being present (or a generic warning
about files from another OS, depending on what else may be in
your computer) when you go through the install process. Ignore
this for now, as we'll be back later to take care of it.
The installation process for Windows 98 should not vary
greatly from the way you would normally set it up. The one major
difference needs to be the location of the Windows installation;
it can't be on the same partition with your NT install, or your
\Program Files folder will contain inconsistent copies of some
Once the installation finishes, make sure your system boots
correctly into Windows 98 before continuing. If Windows 98
refuses to boot, unrepaired disk problems may have occurred
7. Repair your Windows NT boot
Once Win98 is in and running, the last step is to repair the Win
NT/2000 boot files. This will allow you to use the NT boot
loader to choose between NT/2K and Windows 9x.
Repairing the boot files is fairly automatic. Boot the
Windows NT/2000 setup disks -- or the CD-ROM, if
you can boot CD-ROMs -- and select R in Setup to
repair. Choose to repair only the Windows NT boot sector --
nothing else. Note that if your Windows NT/2K installation can't
be found, you should pop in the repair disk you made (you DID
make one in step 2, correct?) and use that to help the repair
program find your installation.
Once the repair operation is finished, boot the computer to
see whether you get the Win NT/2K boot options menu with a new
entry at the bottom for Windows 9X. Usually you will. If not,
you'll need to add a line to the file BOOT.INI, which should be
a read-only file in the root directory of your boot drive.
You'll need to modify the file's permissions so that it's not
read-only in order to change it.
Add the line:
(click for expanded view)
the BOOT.INI file is easy enough -- use
Notepad or another plain-text editor -- but
you'll need to turn off the file's read-only attribute
before you can save it. Also be careful not to edit
anything except the reference to Windows 95/98/Me
to the bottom of the BOOT.INI file, and reboot. The comment
in quotes can be anything you like, as long as it's distinct
from the other menu choices.
The next time you reboot your system, simply choose the
appropriate selection from the boot menu to boot either Win
95/98/Me or NT/2K.
Install NT on a Win2000 PC
Adding Win NT to a Win2000 PC should in some
ways be treated like adding Win95/98/Me to a Win NT/2000
installation. The main reason for this is, on the whole, that NT
cannot recognize Win2000 NTFS partitions (unless you have
Service Pack 6A, and even then it seems to have problems).
Win2000's edition of NTFS contains some features, such as
changes to how permissions work, that are not entirely
backwards-compatible with WinNT. The best thing to do is place
NT on a separate partition, where it can use its own version of
You'll also need to repair Win2000's boot files, just to be
safe. The process for doing this is identical to the repair
process in Windows NT.
Install NT/2000 on a 95/98/Me
Adding Windows NT or Windows 2000 to a
machine that already has Windows 95, 98, or Me on it is much
simpler than the reverse for one simple reason: Windows NT/2000
is smart enough to detect the presence of another operating
system during installation and modifies its boot files
accordingly. Because of this, if you install WinNT/2000 in a
machine that already has another version of Windows on it --
and it doesn't matter what version -- you'll see an
entry in the boot manager for both editions of Windows.
The installation procedure to follow when adding NT/2000 to a
95/98/Me computer isn't enormously different from installing
NT/2K in general. There are, however, a few guidelines to
1. Do not install NT on a FAT32 partition.
This is probably the single most important rule. NT supports
only FAT and NTFS, not FAT32, and can't be installed on a
FAT32 partition. In fact, it generally can't even read FAT32
partitions. So if you're planning to make data readable by both
operating systems, be sure not to place it on a FAT32 partition.
Place shared data either in a FAT partition or on a networked
Also, do not convert a FAT16 partition that has NT installed
on it. Converting a partition with NT installed on it to FAT32
will render it unbootable.
The sole exception to this rule is with Windows 2000. Win2K
can read and write FAT32 partitions without problems. Installing
Win2K on a FAT32 partition, however, means you won't be able to
use NTFS security features on your system partition.
2. Don't use disk compression.
In fact, this is a global rule: Never use disk compression on
any multiple booting system. It's not worth it, and it creates
more problems than it solves. Most drives today are big enough
that disk compression is contraindicated, anyway. Windows Me
won't even install onto a system that has disk compression
3. Do a disk check before an installation.
Lingering disk errors can cause terrible problems later on down
the line when you install an operating system. During Windows
installation, there's a disk check; don't skip this step.
4. Always use a discrete partition for other operating
systems. As with installing Win 95/98/Me on an NT/2K system, this rule
also applies here, and for the same reasons. Installing one
Windows application set over another can cause horribly
unpredictable things to happen. In most cases it will break IE
and Outlook Express, and if shared .DLLs are overwritten, it may
cause other apps to malfunction, too.
If you want to share applications between
operating systems, the best way to do this is to install the app
on one OS, boot the other OS, and then reinstall it into the
exact same folder. However, a few applications may not work
correctly if you do this: for instance, any application that
uses CTL3DV2.DLL or CTL3D32.DLL, since there are discrete
versions of those .DLLs for 95/98/Me and NT/2K. Your safest bet
is to install apps in separate partitions, although a few
programs can be coaxed into running without being reinstalled.
(click for expanded view)
operating system should always reside on its own
partition for the best possible results. Here, a FAT32
partition has been prepped for a new installation of
Another thing to be aware of when adding a new partition to a
Windows 9x machine is how Windows 9x translates
partitions as drives. In some cases, if you add a partition, you
may break your drive-lettering scheme and possibly render your
Windows 9xsystem unbootable.
Here's an example of this: On a computer that had two primary
partitions, C: and D:, I had Windows NT on C: (which was marked
as bootable) and Windows 98 on D:. When I added a third, logical
partition, the drive lettering was thrown off and D: turned into
E:, making Windows 98 unbootable.
There are two simple ways to defeat this. One is to use only
primary partitions (a maximum of four per hard drive) and to add
them in sequence. Another is to add Windows 9x last
whenever you set up a system, to preserve the integrity of the
drive mapping. The downside of this method is that it goes
against the common wisdom of putting 95/98/Me on a system first,
so this is recommended with some reservations. Forcing Win9x to
map drives a certain way is difficult and not always successful.
(Windows NT and 2000 let you map drives any way you like and are
not as prone to this problem.)
Third-party Programs for
Sometimes the easiest thing to do in multiple
boot scenarios is to let someone else take control of the whole
process. The Windows NT/2K multiple boot loader is not simple to
configure and has no easy way to add operating systems that
aren't directly supported. If you're booting between more than
one OS, or various revisions of OSes, the boot loaders you have
may not be enough to do the job.
Boot loaders work in a couple of different ways. Some of them
are installed in a special partition, only a few megabytes in
size that is marked as bootable. When that partition is booted,
the boot loader program takes over and presents the user with a
menu of possible boot choices. Usually the program analyzes the
available partitions at each boot, to determine whether anything
has changed since the last boot.
The best third-party boot loader out there so
far appears to be System
Commander from Vcom.
System Commander automatically detects any changes made to your
PC since the last boot and updates its menus automatically to
reflect those changes.
(click for expanded view)
Commander works with just about any PC-based operating
system to let you choose the OS you want to boot.
The makers PartitionMagic also have a
multiple boot manager program named BootMagic,
which does many of the same things as System Commander and
supports Windows 2000 as well.
another way to run multiple OSes on the same system, but without
using multiple booting. Instead, VMware creates a virtual
computer console on your PC -- basically, a
computer within a computer. The virtual computer runs at about
two-thirds the speed of your real computer and has access to
many of the same resources -- disk drives,
printers, network, etc. This allows you to run one or more
operating systems, as many as you can devote disk space for,
without having to reformat a drive partition or play around with
One main weakness of VMware is it runs only under
Windows NT or Windows 2000, and it won't work in Windows 95, 98,
or Me. VMware also needs a lot of memory and processing power to
get good results: On anything less than a Pentium II 400, it
crawls, and it needs at least 128MB of RAM to really work
well. You can try before you buy, though; the official site
contains instructions on obtaining a 30-day trial license via
(click for expanded view)
lets you run a 'virtual computer' in your computer,
letting you install any operating system you choose. But
it'll only work in NT or Windows 2000 and needs plenty
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