PC Diagnostics, Testing, and Maintenance - Upgrading and Repairing PCs - page 1260

3. The LOGO.SYS file is loaded and displays a startup image onscreen.
4. If the DRVSPACE.INI or DBLSPACE.INI file exists, it is loaded into memory. IO.SYS also
automatically loads HIMEM.SYS , IFSHLP.SYS , and SETVER.EXE .
5. The IO.SYS file checks the system Registry files (SYSTEM.DAT and USER.DAT ) for valid
data and then reads the Registry's Hkey_Local_Machine\System\CurrentControlSet
key to load the device drivers and other parameters specified there.

Phase 2—Loading and Running WIN.COM WIN.COM

1. WIN.COM loads VMM32.VXD . VxDs not already loaded by the VMM32.VXD file are loaded
from the [386 Enh] section of the WINDOWS\SYSTEM.INI file.
2. VMM32 switches the computer's processor from real mode to protected mode; then
the KRNL32.DLL , GDI.EXE , USER.EXE , and EXPLORER.EXE (the default Windows 9x GUI
shell) files are loaded.
3. The desktop settings are loaded, and programs in the StartUp group and the RunOnce
Registry key are run during the last phase of the startup process.

Windows 2000/XP Startup
When you start a Windows 2000 or XP system (which are all based on the same set of in-
tegral code that originated with Windows NT), the boot process is different from that of a
DOSorWindows9x/Mesystem.Insteadofaccessingthe IO.SYS and MSDOS.SYS filesused
by 9x/Me, these operating systems use an OS loader program called Ntldr .
The basic startup process is described in the following step-by-step procedures:
1. The partition boot sector loads Ntldr

Ntldr (NT Loader). It then switches the processor
to protected mode, starts the file system, and reads the contents of Boot.ini . The in-
formation in Boot.ini determines the startup options and initial boot menu selections
(dual-booting, for example). If dual-booting is enabled and a non-NT/2000/XP OS
is chosen, Bootsec.dos is loaded. If SCSI drives are present, Ntbootdd.sys is loaded,
which contains the SCSI boot drivers.
2. Ntdetect.com

Ntdetect.com gathers hardware configuration data and passes this information
to Ntldr

Ntldr . If more than one hardware profile exists, Windows uses the correct one for
the current configuration. If the ROM BIOS is ACPI compliant, Windows uses ACPI
to enumerate and initialize devices.
3. The kernel loads. Ntldr passes information collected by Ntdetect.com to
Ntoskrnl.exe . Ntoskrnl then loads the kernel, Hardware Abstraction Layer ( Hal.dll ),
and Registry information. An indicator near the bottom of the screen details progress.