Multiple Operating Systems
Note: I no longer develop this page. It remains as a legacy resource.
The information on this page includes references to obsolete and seldom-used versions of operating systems. Experienced users only.
A lot of this information is disappearing because computers have become faster and cheaper so people can afford to have more than a single computer to run various operating systems (OSs).
Why Multiple OSs?
There are many reasons for running either a dual-boot or multi-OS computer:
- You can reduce the space dedicated to hardware in your working environment.
- Gamers don't want to endanger their business installation.
- Web designers want to view their sites in various OSs using native browsers.
- IT staff may need to be able to simultaneously work with several versions of Windows.
- Windows users want to experiment with Linux, but need to retain Windows.
- Drivers for legacy hardware are unavailable (e.g. scanners or proprietary legacy hardware).
Possible uses include running older programs for research or gaming.
What if you could run your games in a Windows environment and work in the operating system of your choice? This page discusses the options for doing that.
I'm going to use the following terms:
- Dual boot: running more than a single version of the same operating system (i.e. Windows 10 and Windows 7)
- Multi-OS: running more than a single operating system (OS) on a computer (i.e. Windows 7 and Linux).
Before you attempt to install a dual- or multi-boot environment, you might want to try out one of the software solutions that run alternative software in a separate “virtual environments.”
Hardware has improved to where it is now possible to share resources with another separate OS running “virtually” on top of your current OS.
There are several options to run Windows programs on other operating systems and vice versa. Be sure you don't opt for a solution that is too complex or expensive and that your computer can meet all the performance requirements.
Virtual Environment Software
- Oracle's VirtualBox is strongly recommended.
Windows XP Mode
Windows XP Mode allowed you to run XP programs natively within Windows 7.
Given that Windows 7 or XP are both unsupported, you need to be careful. I recommend uninstalling XP Mode and only running Windows 7 off-line.
The following resources may be useful if you're running XP Mode.
- Using Free Windows XP Mode as a VMware Virtual Machine.
- Compatibility with security: How to run Windows XP in a virtual machine.
- How to Install Windows XP Mode in Windows 7.
- Compatibility with security: How to run Windows XP in a virtual machine.
Dual booting has the advantage that you're running both OSs natively (i.e. the second OS isn't running on top of the original OS).
Dual Booting Linux
You're given the option to retain your existing Windows installation when you install Linux.
Always install Windows first.
Windows does not detect other operating systems and does not feature a boot menu. When you install it, it overwrites your boot sequence and your computer then boots straight into Windows. — Linux Mint
- Linux Mint Installation Guides on multi-boot.
Dual Booting Mac Using Boot Camp
Boot Camp provides the ability to add a native Windows installation on Intel-based Macs.
Boot Camp creates a suitable partition for the Windows installation and the necessary Windows drivers for the installation. Have a look at this guide to see the process:
To remove Windows from your Mac you need only remove Boot Camp. Everything is pretty much automatic. However, if you wish to restore or repair a Boot Camp partition, you might need more help.
- Boot Camp Help
- How to install Windows on your Mac with Boot Camp.
- Boot Camp Support — how to install and use Windows on your Mac with Boot Camp.
- Use your Apple Keyboard in Windows with Boot Camp from Apple.
Using Boot Camp without an Optical Drive
One of the “gotchas” when installing Windows using Boot Camp occurs if you replace your Mac's optical drive with a second hard drive in which case the system may not recognize an external drive at boot time.
I recommend creating an ISO image from a Windows installation media rather than trying to make an external optical drive work.
The solution that worked for me was the use of the rEFInd Boot Manager. It took some experimentation to get it to work.
I've modified Jorge's Windows 8 instructions to install Windows 7 Pro using rEFInd (a fork of rEFIt) on OS X Maverick and to make them clearer:
- Install rEFInd then restart your Mac.
- Let OS X load one time (to be certain that rEFInd loads).
- Reboot again.
- You should see rEFInd (if you don't, press ALT on the reboot cycle).
- Choose EFI Windows (or the name given to your Boot Camp partition).
- Windows should start. (If that doesn't happen, it's because you have chosen the wrong partition. Reboot again and choose other partition until you find the right one.) Let windows start.
- At some stage, Windows will ask you to select a partition for it to install, choose the Boot Camp partition (the one you made earlier) and don't format it.
- Click Next.
- Windows will install without any problems. It may reboot several times — be sure to let windows reboot on the right partition. Since you have rEFInd, you don't have to press ALT all the time.
- Don't bother with the repair disk.
- Configure Windows has you like.
- Install Boot Camp drivers.
- Choose the Mac partition.
- Go to your Root folder and rename folder EFI, to EFI_old (you may need it again). [I simply left rEFInd until I was sure everything worked then uninstalled it.]
- Press ALT
- Windows disk partition will show on Apple boot screen. Select Windows.
- Start using Windows 7. You're done (except for the remaining setup for Windows including updates).
There are alternative solutions like these YouTube videos:
- How to install Windows Boot Camp without an optical drive.
- The complete guide to install Windows on Mac without an internal optical drive or USB (YouTube).
- Installation of Windows on Mac without using Superdrive or USB (YouTube).
Dual Booting Windows Versions
Try Compatibility Mode First
Windows 7 and newer has the ability to run in compatibility mode as far back as Windows 95, in 256 colours, 640 x 480 resolution and more. You might want to give this a try before attempting to create a dual-boot install.
Don't Mix Windows Versions
When installing a second version of Windows, use separate partitions for each (I'd recommend separate hard drives, if possible) so that the resources are not intermingled.
Installing a second version of Windows in the same partition will mix the contents of the two versions of Windows, possibly overwriting key files.
User Files Handled Differently
Windows Vista and later have a very different way of handling many files than XP and earlier, including “user” folders such as My Documents.
- Windows 95 introduced My Documents, but it was located in
- Windows XP introduced multi-user installations as a default, moving My Documents to
C:\Documents and Settings\[user name]\My Documentsand creating All Users for settings and documents shared between users.
- Windows Vista changed Documents and Settings to the simpler Users and My Documents was now located in
C:\Users\[user name]\My Documents.
Instead of My Documents on the desktop, the User folder appeared, containing My Documents as well as moving the My Music, My Pictures, etc. from My Documents into the User's folder. The “All Users” folder became the “Public” folder acknowledging that sharing went beyond users on the same computer to network sharing.
Other important changes made in Vista were to move the location of the Application Data folders and to reclassify them under Local, LocalLow and Roaming (with the majority of application using the Roaming to allow sharing between computers as well as between users).
Windows 7, 8 (8.1) and 10 use pretty much the same disk layout as Vista for key files.
Sharing With Different Windows Versions
Windows XP and later should be run on the NTFS file system, but if you want to be able to see the information on these partitions from Windows 9x you'll need to use Fat32 — at least for a common partition containing the files you wish to share.
Windows 8, 8.1 and 10 still use NTFS by default, but can use ReFS, which has several advantages including error correction but retains the ability to view files on NTFS.
There are great advantages to NTFS, including the ability to handle much larger drives, automatic compression and improved file features, such as private folders. Unless you need to see and dynamically alter the information on the Windows 7 or XP partition when booting to the Windows 9x installation, I'd use NTFS.
If you choose NTFS, Windows 9x will be unable to "see" the Windows 7 or XP drive. You'll have to share documents with one of several methods, including:
- A common drive or partition formatted with the FAT32 file system. This can be either an internal drive or an external USB drive.
- A USB thumb-drive (you'll need to install drivers for Windows 98SE). This works if you seldom share information.
Obviously, this has limitations if you are going to be continually sharing dynamic information and it will be impossible to share programs.
Windows 9x Least Flexible
Windows 9x demands the C: primary partitions) and is a predatory operating system that will try to write data into any drive or partition that it can read (FAT16 in particular). It will offer to format anything it cannot read (such as NTFS or HPFS) if it can "see" it.
For this reason, I'd suggest using an older PC to run these older versions of Windows. If your programs need direct DOS hardware access, you can create serious issues in dual-booting with newer versions of Windows. A Virtual Environment install might be a better solution.
Can't Share Program Installations
You will need to install the programs in both versions of Windows, so that the correct information is written into the Windows Registry for each operating system, even if you are sharing the program data.
HyperOS gives you instantly available spare cloned Windows systems which you can switch to with a double click. Having HyperOs is so much better than having a backup.
Hardware Advice: Get a solid state disk. You need two data storage devices, one of which is fast. — HyperOS
- The Geek version runs up to 10 Windows systems from your boot drive and up to 10 more (one per partition). The SuperGeek version upgrades this to 24 partitions.
- Each active partition becomes the C: drive (required by Windows base files and some other software).
Dual Booting Resources
Install more than one operating system (multiboot) in Windows. Some of the resources refer to unsupported versions of Windows but can still be useful references.
- Dual Booting explained: How you can have multiple operating systems on your computer.
- How to Dual Boot Windows 10 with Other Versions of Windows, macOS and Linux
- Multiple operating systems and file system compatibility
- Determining How Many Operating Systems to Install
- Repair the boot menu on a dual-boot PC
The Multi-OS Environment
The multi-operating system environment has a single computer booting more than one (and usually more than two) operating systems.
Unlike booting between different versions of Windows, there tends to be much more that is different than simply the operating system. File systems are often (but not always) incompatible.
You can use various hardware devices to enable you to boot to alternative operating systems. The advantage is that you don't have to worry about one operating system damaging the information or file systems in another operating system's partition. The disadvantage is that it is impossible to share data and/or programs because they are physically separated.
Removable Drive Bays
The removable drive bay is an option that is probably not going to work on newer systems but might be suitable if you're running Pentium-era computers.
Designed for older ATA drives, the idea was that can be easily swapped for your various OSs. You should be sure to purchase the same brand and model of drawer if you wish to leave the hard drives in the bays and ensure that the correct drawer is purchased if you are running ATA66 or better drives.
As USB throughput improved, these drawer systems became obsolete.
Removable USB Drives
Modern USB connections and drives have improved greatly and computers can boot from USB drives. USB 3 throughput is very fast, making this option more realistic.
Booting to a USB device might require you to make changes in the BIOS or your computer might provide quick access to a boot priority like pressing a function key like F12.
- Make a Bootable External Hard Drive and Install Windows 7/8.
- How to select a different startup disk (Intel-based Macs).
- How to Create a Bootable Linux USB Drive Easily (YouTube).
- Dual boot USB drive — tutorial A multi-booting hard drive you can connect to any computer.
If your need for changes is infrequent, you might consider simply swapping the cables inside your computer when you need to switch operating systems. This requires you to open the computer case and is not an option for laptops, but the only cost is the price of the additional hard drive(s).
Warning! Newer computers continue to have power when they are shut down. Be sure to remove the power cable from the computer and ensure external devices and the monitor are turned off (a common power bar works great for this).
You might try changing the boot sequence in the BIOS to boot to a different drive or to enable/disable SATA and IDE drive options. This should only be contemplated if you understand the BIOS/UEFI boot environments and can comfortably experiment with this option.
There are various boot manager program that dynamically will allow you to switch between various operating systems. These program can “see” various types of file systems and usually provide some sort of a boot menu that intervenes in the normal boot up of your computer so that you can make a choice.
- zBoot Manager.
- BootIt Bare Metal contains a Boot Manager which provides a full set of options for each boot item, giving the user an unequaled level of flexibility in configuring (non-UEFI) multi-boot systems.
- One of the oldest is System Commander from V Communications. System Commander allows up to 32 Operating Systems in a DOS partition or each in their own primary or logical partition.
IBM OS/2 and ECS
There is multi-OS information more relevant to OS/2 or eCommStation users in the OS/2 Resources Section, although much of the information is quite dated compared to what is on this page.
OS/2 and eCommStation provides a stable and work-friendly business operating system which wins over those that take the time to learn its advantages. However, the ability to play games and support for much hardware and accessories is either unavailable or not as advanced.
Partitioning Your Hard Drive
Backup Before Partitioning
You should backup your data in case something does go wrong during any of the procedures on this page. It is strongly recommended that you make routine backups because hardware failures, viruses and other disasters happen, not to mention human error.
A single hard drive can be formatted with one or multiple partitions. The first (or Primary) partition is made active (bootable) and any other partitions are grouped into a Logical partition.
The image below shows an old Windows 98 system with a FAT32 primary partition (C:) and a logical partition containing two FAT16 partitions (D: and E:).
Modern Windows systems are more likely to contain only NTFS partitions.
Can I be Seen?
Each of these partitions are assigned a drive letter by Windows, if it can “see” the file system on that partition, and ignored if it can't.
Whether or not a particular file system is visible to the host OS depends upon the version of Windows and if there are operating systems other than Windows installed.
Built-in Partition Utilities
The traditional tool for creating and deleting partitions is FDISK — a command-line utility relic from DOS.
However, you can boot to the Windows installation CD on most computers, then create or delete partitions.
If you delete or format a partition, it will erase all information on that partition.
Windows 7 Disk Management
Use Windows 7's built-in disk management software (right-click My Computer and left-click Manage then select Disk Management).
You might be unable to see a drive if you are using several USB drives on multiple systems. Run Disk Management to create a different drive letter for each drive.
Third-Party Partition Utilities
Third-party utilities can have advantages as they are better able to “see” and deal with partitions created and used by other OSs.
Beware of Possible Gottchas
Partition Magic was the first partition utility to allow for non-destructive partition sizing. When run in Windows it would offer to “fix” partitions in a multi-OS system.
Because not all operating systems create partitions the same way, this can make destroy partitions containing other operating systems such as OS/2. If this happens, you won't be able to recover the data on those partitions.
MiniTool Partition Wizard
MiniTool Partition Wizard Home Edition is a free partition manager software that supports 32/64 bit Windows Operating System including Windows XP and newer.
Users can perform complicated partition operations such as:
- Explore/copy/convert/recover/hide partitions.
- Create/delete/format partitions.
- Extend/resize/split partitions.
- Change drive letter.
- Set active partition.
Business users are required to purchase MiniTool Partition Wizard Professional Edition.
BootIt Bare Metal
BootIt Bare Metal is a utility that allows you to Manage your partitions, install and boot multiple operating systems with ease, back up and restore partitions or entire drives.
Bare Metal Boot Manager provides options for configuring (non-UEFI) multi-boot systems.
- Multibooting in Windows XP Made Easy includes non-Windows OSs.
- Managing Multiple Operating Systems HOWTO is a useful resource for those wishing to run multiple OSs with Linux.
What happens when something ceases to work or if you decide to remove one of the partitions? You need to be able to recover any partitions you wish to continue to use.
Fixing the MBR
Repairing Windows installations generally means working with the Master Boot Record (MBR).
There are numerous file systems, many of which are specific to one or more operating systems. Because they handle information in different ways, they each have advantages and disadvantages. As file systems age, their limitations increase, much like the limitations of the operating systems they run on.
For the most part, the differences are transparent to the average user, except during installation — if choices between two or more file systems are offered.
Various PC File Systems
The more common PC file systems are shown in the table below (in order of increasing superiority). See Wikipedia's list of default file systems.
|File System:||Description:||Used By:|
|FAT16||File Allocation Table (16-bit)||DOS, Windows 3x, 95, OS/2, digital cameras|
|FAT32||File Allocation Table (32-bit)||Windows 95B, 98, Me and XP|
|NTFS||New Technology File System||Windows 2000, XP, Vista, 7, 8 and 10|
|exFAT||Extended File Allocation Table||Windows XP, Vista, 7, 8 and 10|
|ReFS||Resilient File System||Windows Server 8 & later|
|HPFS||High Performance File System (16-bit)||OS/2 and early NT4|
|JFS||Journal File System||OS/2, eCS|
|HFS+||Hierarchical File System||Mac|
|APFS||Apple File System||macOS, iOS, tvOS and watchOS.|
|Ext2/3||Extended File System||Linux|
|ZFS||Sun Microsystems Filesystem||Solaris, FreeBSD, Linux.|
Can You See Me?
Operating systems generally cannot “see” the file systems for which they were not designed (at least not without third-party utilities). For example, Windows 98SE would not be aware of an NTFS partition, but would see and be able to work with files on either FAT32 or FAT16 partitions or drives. Generally, Windows can see the file systems for the versions prior to the version you're using.
In many cases, operating systems can use multiple file systems and your choices to use one over the other might include security concerns, data reliability, speed of access, backwards compatibility with earlier systems or any number of other reasons.
Prepare for Multi-OS Installs in Advance
One caveat: You should set up the partitions prior to installing the operating system(s) since adding or changing the file system can alter the drive lettering as it is viewed by the various operating systems. Operating systems beyond the C: partition might not be able to boot or if they boot may be unable to locate programs on other partitions.
Other File Systems
Of course, there are many other file systems and the comparisons are interesting. Don't forget to take into account the age of the file system. Older technology is not going to have the hind sight available to newer releases.
- Working with File Systems
- A comprehensive guide to sharing your data across multi-booting Windows, Mac, and Linux PCs.
Windows File Systems
- Microsoft's Overview of FAT, HPFS, and NTFS File Systems
- Choosing a file system: NTFS, FAT, or FAT32.
- DOS FAT 12/16/32, VFAT
- File systems (FAT, FAT8, FAT16, FAT32 and NTFS)
- New Technology File System (NTFS) has interesting history, but is somewhat cluttered by ads at the top.
Linux File Systems
OS/2 File Systems
- High Performance File System (HPFS).
- Overview of the JFS file system.
- A Comprehensive Guide to Sharing Your Data Across Multi-Booting Windows, Mac, and Linux PCs.
- File systems HOWTO by Martin Hinner documents how to see other file systems (including HPFS and OS/2 LVM) from various operating systems, including NT4, DOS and Linux.