Chapter 23: Exploring the Windows Boot Environment
way operating system features are used. Windows Vista doesn’t use these boot facili-
ties. Instead, startup is controlled using the parameters in the BCD data store:
• Entries in the BCD data store identify the boot manager to use during startup
and the specific boot applications available.
• Windows Boot Manager controls the boot experience and enables you to choose
which boot application is run.
• Boot applications load a specific operating system or operating system version.
For example, a Windows Boot Loader application loads Windows Vista.
Because BCD abstracts the underlying firmware, you can boot BIOS-based and EFI-
based computers in much the same way—just as you can computers based on other
firmware models. The BCD store is contained in a file called the BCD registry.On
BIOS-based operating systems, the BCD registry file is stored in the \Boot\Bcd direc-
tory of the active partition. On EFI-based operating systems, the BCD registry file is
stored on the EFI system partition.
The BCD store contains multiple entries. On a BIOS-based computer, you’ll see the
• One Windows Boot Manager entry. There is only one boot manager, so there is
only one boot manager entry.
• One or more Windows Boot Loader application entries, with one for each
Windows Vista operating system or later versions of Windows installed on the
• One legacy operating system entry. The legacy entry is not for a boot applica-
tion. This entry is used to initiate Ntldr and Boot.ini so that you can boot into a
pre-Windows Vista operating system. If the computer has more than one pre-
Windows Vista operating system, you’ll be able to select the operating system to
start after selecting the legacy operating system entry.
Working with Boot Conﬁguration Data
Several tools are available to work with and manage the BCD, including the following:
• Startup and Recovery
• System Configuration utility
• BCD Editor
The sections that follow discuss how these tools are used.
Using the Startup and Recovery Dialog Box
The Startup and Recovery dialog box enables you to select the default operating system
to start if you have multiple operating systems installed on your computer. You can also
specify timeout values for operating system selection lists and recovery options.