68 Computer Service and Repair
the user to select which operating system to start.
If no selection is made, the Windows 7 operating
system will start by default.
You could also conFigure a multiple-
boot system, which contains more than two
operating systems. For example, you could have
Windows 2000, Windows XP, Windows Vista, and
Windows 7 installed on the same computer. You
could also add a non-Microsoft operating system,
such as Linux.
At the time of this writing,
you cannot create a
dual-boot or multiple-
boot system with Windows 8. It is only possible by
installing a virtual software program on an
existing operating system and then installing
Windows 8 into the virtual partition.
Virtual Machine
When a computer is configured as a dual-
boot or multiple-boot system, you can only run
one operating system at a time. However, a virtual
machine can be created using a special software
application that allows more than one operating
system to be executed at the same time. A
computer that runs two operating systems at the
same time is referred to as a virtual machine or
virtual PC. The Microsoft application for creating
a virtual machine is called Windows Virtual PC.
There is also a third-party vender that markets
virtual machine software called VMware.
When two operating systems are running
at the same time, they must share the CPU and
the RAM. Sharing the CPU and RAM negatively
impacts computer performance when compared to
a dual-boot or multiple-boot system.
Common Mobile Device
Operating Systems
In general, mobile operating systems are
designed for portable devices with limited
hardware resources, such as cell phones, tablets,
and some gaming hardware. Although some
mobile operating systems do appear on larger
devices, such as laptops and tablets, they are
Tech Tip
process. The following details the Windows Vista,
Windows 7, Windows 8 boot sequence:
1. BIOS performs the POST.
2. BIOS locates the MBR and loads it into
memory.
3. BIOS locates and loads the Windows Boot
Manager (bootmgr).
4. Windows Boot Manager reads the BCD fi le
and displays the boot menu.
5. Windows Boot Manager starts the
Windows Boot Loader (winload.exe) when
Windows Vista, Windows 7, or Windows 8 is
selected or if started automatically.
6. The Windows Boot Manager loads
ntoskrnl.exe
and
hal.dll
into memory and scans the registry
for device drivers to load. It then passes
control to the kernel.
7. The kernel loads the device drivers and
hal.dll
and initializes the computer settings using the
values stored in the system registry.
8. The kernel starts the Session Manager (smss.
exe), which creates the system environment.
9. The operating system switches to graphics
mode and the
winlogon.exe
fi le is loaded, thus
starting the Logon Manager (winlogon.exe).
10. The Logon Manager allows the user to begin
the logon process.
When answering questions related to the
Windows Vista, Windows 7, and Windows 8
boot sequence, remember these operating
systems use the Windows Boot Loader file,
winload.exe, not ntldr.
A+ Note
Dual-Boot and Multiple-Boot
Systems
When two operating systems are installed
on a single computer, it is referred to as a dual-
boot system. For example, Windows Vista and
Windows 7 can both be installed on the same
computer, resulting in a dual-boot configuration.
The Windows 7 Windows Boot Manager allows