Dual Booting :How You Can Have Multiple Operating Systems on Your Computer

Most computers ship with a single operating system, but you can have
multiple operating systems installed on a single PC. Having two
operating systems installed — and choosing between them at boot time —
is known as “dual-booting.”
Google and Microsoft ended Intel’s plans for
dual-boot Windows and Android PCs, but you can install
Windows 8.1 alongside Windows 7, have both Linux and Windows on the same computer, or install Windows or Linux alongside Mac OS X.
How Dual-Booting Works
Your computer’s operating system is generally installed on its
internal hard drive. When you boot your computer, the BIOS loads the
boot loader from the hard drive and the boot loader boots the installed
operating system.
There’s no limit to the number of operating systems you he installed —
you’re not just limited to a single one. You could put a second hard
drive into your computer and install an operating system to it,
choosing which hard drive to boot in your BIOS or boot menu. You could also boot an operating system — like a
live Linux system or a Windows To Go USB drive — from external storage media.
Even if you only have a single hard drive, you can have multiple operating systems on that hard drive. By p
artitioning the drive into several different partitions,
you can have one partition for one operating system and another
partition for another operating system, splitting the drive between
them. (In reality, many operating systems use multiple partitions. The
point is you’re devoting part of the drive to one operating system and
part of the drive to another.)
When you install a Linux distribution, it typically installs the Grub
boot loader. Grub loads instead of the Windows boot loader at boot time
if Windows was already installed, allowing you to choose the operating
system you want to boot. Windows also has its own boot loader, which can
be used to select between different versions of Windows if you have
more than one installed.
Why Bother Dual-Booting?
Different operating systems have different uses and advantages.
Having more than one operating system installed allows you to quickly
switch between two and have the best tool for the job. It also makes it
easier to dabble and experiment with different operating systems.
For example, you could have both Linux and Windows installed, using
Linux for development work and booting into Windows when you need to use
Windows-only software or play a PC game. If you like Windows 7 but want
to try out Windows 8.1, you could install Windows 8.1 alongside Windows
7 and choose between the two at boot time, knowing you’ll always be
able to go back to Windows 7. If you’re using a Mac, you can have
Windows installed alongside Mac OS X and boot into it when you need to
run Windows-only software.
You could use virtual machine software instead of setting up a
dual-boot system, but a dual-boot system lets you actually use both
operating systems on your hardware at full, native speed. You don’t have
to deal with the overhead of a virtual machine, which is especially bad
when it comes to 3D graphics. The downside is you can only use one of
your installed operating systems at a time.
Switching Between Operating Systems
If each operating system is installed to a separate drive, you could
actually switch between both by selecting a different drive as your boot
device every time you boot. This is inconvenient and you’ll probably
have two operating systems installed on the same drive, so that’s where a
boot manager comes in.
Switch between your installed operating systems by rebooting your
computer and selecting the installed operating system you want to
use. If you have multiple operating systems installed, you should see a
menu when you start your computer. This menu is typically set up when
you install an additional operating system on your computer, so you
won’t see if you just have Windows installed or just have Linux
installed.
Setting Up a Dual-Boot System
Setting up a dual-boot system is fairly easy. Here’s a quick overview of what to expect:
- Dual Boot Windows and Linux: Install Windows first
if there’s no operating system installed on your PC. Create Linux
installation media, boot into the Linux installer, and select the option
to install Linux alongside Windows. Read more about setting up a dual-boot Linux system.
- Dual Boot Windows and Another Windows: Shrink your
current Windows partition from inside Windows and create a new partition
for the other version of Windows. Boot into the other Windows installer
and select the partition you created. Read more about dual-booting two versions of Windows.
- Dual Boot Linux and Another Linux: You should be
able to dual-boot two Linux distributions by installing one first and
then installing the other. Choose to install the new Linux system
alongside your old Linux system. Resize your old Linux partitions in the
installer and create new ones to make space if the installer won’t do
this autoamtically.
- Dual Boot Mac OS X and Windows: The Boot Camp utility included with Mac OS X allows you to easily set up a Windows dual-boot system on your Mac.
- Dual Boot Mac OS X and Linux: Boot Camp doesn’t allow you to set up a dual-boot Linux system, so you’ll need to do a bit more footwork here. Follow our guide to installing Linux on a Mac for more details.
