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System Files Reference

Published: November 03, 2005

When you install the Microsoft Windows XP Professional operating system, the Setup program creates folders on your system drive into which it places files that the system requires. Knowing the names and locations of essential system files can help you understand and troubleshoot your Windows XP Professional installation.

For information on how to obtain the Windows XP Professional Resource Kit in its entirety, please see http://www.microsoft.com/mspress/books/6795.asp.

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Related Information
System Files
Startup Files
Folders on the Local Disk
Windows Folder
System32 Folder
Extracting Files from the Operating System CD
Using the Copy Command in Recovery Console
Using the Expand Command in Recovery Console
Additional Resources

Related Information

  • For information about troubleshooting Startup and running Recovery Console, see Chapter 29, “Troubleshooting the Startup Process.”

  • For information about general troubleshooting concepts and strategies, see Chapter 27, “Understanding Troubleshooting.”

System Files

The following files are core components of the Windows XP Professional operating system. If you install Windows XP Professional as an upgrade from Microsoft Windows 2000 or earlier, the files listed in Table A-1 are located in the Windows\System32 folder or in Winnt\System32.

Table A-1 Essential System Files

File Name

Description

Ntoskrnl.exe

Executive and kernel.

Ntkrnlpa.exe

Executive and kernel with support for Physical Address Extension (PAE), which allows addressing of more than 4 gigabytes (GB) of physical memory.

Hal.dll

Hardware abstraction layer.

Win32k.sys

Kernel-mode part of the Win32 subsystem.

Ntdll.dll

Internal support functions and system service dispatch stubs to executive functions.

Kernel32.dll

Advapi32.dll

User32.dll

Gdi32.dll

Core Win32 subsystem DLLs.

Startup Files

The following files are essential to the startup process. All files listed in Table A-2 are located in the boot or root directory (for example, C:\) of your Windows XP Professional installation.

Table A-2 Essential Startup Files

File Name

Description

Ntldr

Reads the Boot.ini file, presents the boot menu, and loads Ntoskrnl.exe, Bootvid.dll, Hal.dll, and boot-start device drivers.

Boot.ini

Contains options for starting the version of Windows that Setup installs and any preexisting Windows installations.

Ntdetect.com

After the boot selection is made, Ntldr loads and executes this 16-bit real-mode program to query the computer for basic device and configuration information. This information includes the following:

  • The time and date information stored in the system’s CMOS (nonvolatile memory).

  • The types of buses (for example, ISA, PCI, EISA, Micro Channel Architecture [MCA]) on the system and identifiers for devices attached to the buses.

  • The number, size, and type of disk drives on the system.

  • The types of mouse input devices connected to the system.

  • The number and type of parallel ports configured on the system.

Pagefile.sys

Contains memory data that Windows is unable to fit into physical RAM. During Startup, the virtual memory manager moves data in and out of the paging file to optimize the amount of physical memory available to the operating system and applications.

Ntbootdd.sys

If either the boot or system drives are SCSI-based, Ntldr loads this file and uses it instead of the boot-code functions for disk access.

Folders on the Local Disk

Setup creates the following folders (shown in Table A-3) on your local disk by default when installing Windows XP Professional.

Note When Windows XP Professional is installed as an upgrade from Windows 2000 or earlier, Setup installs the operating system into the existing Winnt folder. A Windows folder is not created.

Table A-3 Default Local Disk Folders

Folder Name

Contents

Documents and Settings

Account information for each user who is granted access on the computer. Each user account is represented by a subfolder assigned the user name and called the user profile. Folders under each user account folder include My Documents, Desktop, and Start Menu.

Program Files

Installed applications, such as Microsoft Internet Explorer or Microsoft Office.

WINDOWS or WINNT

Entire operating system.

Windows Folder

The Windows folder and its subfolders contain the operating system files for your Windows XP Professional installation (as shown in Table A-4).

Table A-4 Windows Folder and Subfolders

Folder Name

Contents

WINDOWS or WINNT

Miscellaneous operating system and application files (for example, Control.ini, Desktop.ini, Notepad.exe, and System.ini files)

Addins

ActiveX controls (.ocx) files

AppPatch

Application compatibility files

Config

Musical Instrument Digital Interface (MIDI) instrument definition files

Connection Wizard

Internet connection files that are used when a computer starts Windows for the first time

CSC

Offline files that are used during client-side caching

Cursors

Cursor and icon files

Debug

Log files

Downloaded Program Files

Downloaded program files

Driver Cache

Uninstalled driver files

ehome

Used by Windows Media Center Edition

Fonts

All font files

Help

Help files

Ime

Language files

ime (x86)

Language files for x86-based systems

inf

Device driver INF files

Installer

Cached Windows Installer (.MSI) files

Java

Java files

Media

Sound and music files (for example: *.wav and *.midi)

MS

Installation folder for Microsoft Systems Management Server (SMS) client

Msagent

Microsoft Agent files (Microsoft Agent is a set of programmable software services that support the presentation of interactive animated characters within the Microsoft Windows interface.)

Msapps

Files that support backward compatibility in applications

Mui

Multi-user interface files

Offline Web Pages

Downloaded Web pages for offline reading

PCHEALTH

Help and Support Center files

PeerNet

MSSL 2.0 files

PIF

Program information files (PIFs) for MS-DOS-based programs

Prefetch

Data files related to enhancing the speed at which applications start

Provisioning

Schemas for creating wireless profiles

Registration

COM+ files. (COM+ files are enhancements to the Microsoft Component Object Model [COM].)

Repair

Registry backup files (These files are updated if you use NTBackup and choose to back up system state files.)

Resources

User interface files

SchCache

Schema cache folder

Security

Log files, templates for snap-ins, and security database files

Setupupd

Dynamic Update storage location

SoftwareDistribution

Used by Automatic Updates

Srchasst

Search assistant files

System

Backward-compatibility files related to the System folder (for example, applications that look for a System folder)

system32

Core operating system files (For more information, see “System32 Folder” later in this appendix.)

Tasks

Scheduled Task files

Temp

Temporary files

twain_32

Imaging files (for scanners)

Web

Printer and wallpaper files

WinSxS

Side by Side (shared components)

System32 Folder

The System32 folder and its subfolders contain the core operating system files for your Windows XP Professional installation. Table A-5 describes the System32 files.

Table A-5 System32 Folder and Subfolders

Folder Name

Contents

system32

Essential system files (for example, Hal.dll and Ntoskrnl.exe files).

1025, 1028, 1031, 1033, 1037, 1041, 1053, 2052, 3076

Localization (language) files for a specific language, corresponding to the number assigned to this folder. This folder remains empty unless Windows XP Professional is localized for this particular language.

CatRoot

Catalog files and signature files.

CatRoot2

Catalog files and signature files.

Com

Component Object Model (COM) objects.

Config

Registry files and event logs.

Dhcp

DHCP database files.

DirectX

DirectX files.

Dllcache

Windows File Protection backup files.

Drivers

Installed drivers.

Export

Encryption Pack installation files.

Group Policy

Group Policy administrative templates and script files.

Ias

Internet Authentication Service files.

Icsxml

Universal Plug and Play files.

Ime

Language files.

Inetsrv

Internet Information Services files.

Macromed

Macromedia files.

Microsoft

Cryptography files.

MsDtc

Microsoft Distributed Transaction Coordinator files.

Mui

Multi-user interface files.

Npp

Network Monitor and trace files.

NtmsData

Removable Storage Manager (RSM) database.

Oobe

Windows Welcome files.

Ras

Remote access server encryption files.

RemoteStorage

Remote Storage Service (RSS) database.

Restore

Data files or System Restore–related files.

Rpcproxy

RPC Proxy files (RPCProxy.dll).

Setup

Optional component manager files.

ShellExt

Shell extension components.

Smsmsgs

SMS Site Component Manager files.

SoftwareDistribution

Used by Automatic Updates (Windows XP Service Pack 2).

Spool

Print spooling files.

Usmt

User State Migration tool.

Wbem

Web-based Enterprise Management data files. Windows Management Instrumentation (WMI) is the Microsoft implementation of WBEM.

Wins

WINS database files.

Extracting Files from the Operating System CD

It is usually recommended that you use Add or Remove Programs in Control Panel to install and uninstall components, applications, and support software from the Windows XP Professional operating system CD. If system files are missing or damaged, you can run Windows XP Professional Setup from the operating system CD and choose the option to repair your existing installation. In some cases, however, you might need to extract a system or startup file directly from the operating system CD.

Warning If you install incorrect versions of system or startup files or if you install files to incorrect locations, your system might not operate as expected or might not start. Use the method described in this section only if your product support representative indicates that it is necessary to manually retrieve a compressed file from your operating system CD.

The /i386 folder on your Windows XP Professional operating system CD contains system and startup files in compressed form. If you need to replace a file in your Windows XP Professional installation, you can use the copy or expand command in Recovery Console to extract the needed file from the operating system CD. Use the copy command unless you are extracting a file from a .cab file, such as Driver.cab. When extracting a file from a .cab file, use the expand command.

When you use Recovery Console to extract a compressed file from the operating system CD, you must use exact file names for the compressed and uncompressed files. Table A-6 illustrates compressed and uncompressed file names.

Table A-6 Compressed and Uncompressed File Names

Compressed File Name

Uncompressed File Name

Ntoskrnl.ex_

Ntoskrnl.exe

Hal.dl_

Hal.dll

Using the Copy Command in Recovery Console

If a file is not within a .cab file, you can use the copy command in Recovery Console to extract the file from the operating system CD and place it on your local disk in a Windows XP Professional installation. When you use the copy command to extract a file to a destination on your local disk, the file is automatically uncompressed. For more information about running Recovery Console, including how to add it to your startup options, see Chapter 29, “Troubleshooting the Startup Process.”

Use the copy command with the following syntax:

copy source [destination]

Table A-7 describes the parameters that you can use with the copy command.

Table A-7 Parameters for the Copy Command

Parameter

Description

Source

Specifies the file to be copied

Destination

Specifies the directory and/or file name for the new file

Source can be removable media, any directory within the System32 directory of the current Windows installation, the root of any drive, the local installation sources, or the Cmdcons folder. (The C:\Cmdcons folder is the Recovery Console installation folder.)

Destination can be any directory within the System32 directories of the current Windows installation, the root of any drive, the local installation sources, or the Cmdcons folder. If you do not specify a destination, the command defaults to the current directory. The copy command prompts you if the destination file already exists. The destination cannot be removable media.

The copy command does not support replaceable parameters (wildcards).

Using the Expand Command in Recovery Console

To extract a file from a .cab file on the operating system CD and place it on your local disk in a Windows XP Professional installation, start Recovery Console and use the expand command. When you use the expand command to extract a file to a destination on your local disk, the file is automatically uncompressed. For more information about running Recovery Console, including how to add it to your startup options, see Chapter 29, “Troubleshooting the Startup Process.”

Use the expand command with the following syntax:

expand source [/f:filespec][destination][/y][/d]

Tables A-8 describes the parameters that you can use with the expand command.

Tables A-8 Parameters for the Expand Command

Parameter

Description

source

Specifies the file that you want to expand. Cannot include wildcards.

destination

Specifies the directory for the new file; the default is the current directory.

/y

Suppresses the overwrite prompt when you expand or extract files.

/f:filespec

If the source contains more than one file, this parameter is required to identify the specific file or files that you want to expand. Can include wildcards.

/d

Lists the files contained in the cabinet file without expanding it or extracting from it.

  • The destination can be any folder within the System32 folder of the current Windows installation, the root of any drive, the local installation sources, or the Cmdcons folder.

  • The destination cannot be removable media.

  • The destination file cannot be read-only. Use the Attrib command to remove the read-only attribute.

  • If the destination file already exists, the expand command prompts you for confirmation to overwrite the file unless you include the /y parameter.

Additional Resources

The following resources contain additional information related to this appendix.

Related Information

  • Chapter 27, “Understanding Troubleshooting.”

  • Appendix C, “Tools for Troubleshooting.”

  • Chapter 28, “Troubleshooting Disks and File Systems.”

  • Chapter 29, “Troubleshooting the Startup Process.”

  • Windows XP Professional Help and Support Center, for more information about running and troubleshooting Windows XP Professional. Search using the keywords troubleshooting and recovery console.

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