With NT Workstation, Windows 2000, and Windows XP, there are two types of partitions that are important during the boot process-the system partition and the boot partition. The system partition is the active drive partition that has the files needed to load the operating system. The system partition is normally the C: drive (the active partition). The boot partition is the partition or logical drive where the operating system files are located. One thing that people sometimes can be on the same partition. These partitions are where certain boot files are located.

Every operating system needs specific files that allow forget is that the system partition and the boot partition the computer to boot. These files are known as system files or startup files. The system files and their specific location on the hard drive are listed in Reading about Windows XP files can be confusing because the file locations frequently have the entries %systemroot% and %systemdrive%. This is because computers can be partitioned differently. If you install Windows XP onto a drive letter (a partition or logical drive) other than the active partition (normally C), the startup files can be on two different drive letters.

Also, you do not have to take the default folder name of WIN NT or WINDOWS (depending on the type of installation) to install XP. To account for these different scenarios, Microsoft uses the %systemroot% to represent the boot partition, the partition and folder that contains the majority of the Windows XP files. %systemdrive% represents the root directory and on a computer with a single operating system, this would be.

The boot process is actually quite involved, but the major steps are as follows:

• Power on the computer.

• POST executes.

• BIOS searches CMOS for the boot device order and checks for a boot sector. If the boot device is a hard drive, BIOS reads the Master Boot Record (MBRl. and locates and loads the information into sector 0 of the system partition. The contents of sector 0 define the type of file system, the location of the bootstrap loader file, and start the bootstrap loader. With Windows Xp, this file is NTLDR.

• NTLDR starts in real mode so that 8- and 16-bit softwares can be loaded. Then XP is switched to 32-bit mode and the file system begins to load.

• NTLOR reads the BOOTINI file and displays the various operating system choices contained within the BOOTINI file. If something other than Windows XP is chosen, the BOOTSECTOOS file takes over. If WindowsXP is chosE:n, the NTDETEClCOM file executes.

• NTDETECTCOM detects the computer's hardware and ACPI tables are read so that XP can detect power management features.

• NTLOR passes the hardware information to the NTOSKRNL.EXE file.

• The operating system kernel, NTOSKRNL.EXE, executes and the HAL.OLL file loads. HAL (Hardware Abstraction Layer) is a layer between the operating system and the hardware devices. The HAL allows Windows XP to run with different hardware configurations and components without affecting (or crashing) the operating system.

• The registry key HKEY LOCAL MACHINE\System loads. This registry key is located in the %systemroot%\System32\Config\System file. This key has information found during the hardware detection process and is used to determine which device drivers to load.

• The operating system kernel initializes and NTLOR passes control to it. The Starting Up process bar displays. During this time, a hardware key is created, device drivers load, and services start.

• The WINLOGON.EXE file executes and the log-on screen appears. While the log-on process is occurring, XP detects plug and play devices.