What is a computer registry?

Joe Alt Saturday, 13 November 2010 905583.doc

The Registry is a database full of files of how to configure your system. It can be used for one or more uses. It was invented as a result of DOS not being good enough to hold all configuration files so it was invented to improve the efficiency and speed of the computer. It is nowhere near perfect yet but hopefully, will improve in the future. There is a programme to clear up any unnecessary files within this database which gets rid of any unwanted files. Without the Registry, the computer would not be able to function properly.

The Registry can hold information about what is in the computer such as the hard drive and graphics cards. The other information it has is what documents you can collate, the personal settings, e.g., background, mouse settings and colour schemes and also it has the programmes which are on the computer, such as Word and Google Chrome.

The Spyware and Viruses and the rights of these, changes your Registry for malicious purposes, so Anti Virus and the other Anti programmes work on the principal that there shouldn’t be any unauthorised access to the Registry and that its own databases of all malicious programmes has helped to identify the unwanted programmes.

The Registry is a database and within the database it has pre-defined keys, such as HKey_Users which have the relevant files for the active user. If one user locked their account and another logged in, the HKey_Users will drop the locked account for now and load up the current account.

Changing the Registry is possible but risky and unless you know what you are doing, is not the best idea. If you are editing the Registry, for whatever reason, make sure there is a recent backup so you can restore the Registry if there is a mistake. I suggest before you get to this stage, you try System Restore which will not damage the computer as much as the Registry would. You can change anything on your computer by using the Registry such as the SubKeys, the values and rename a Subkey/value.

Information source (the internet)

Every operating system and application needs a place to store configuration settings and user preferences. As computers have become more complex, so have the methods of storing this data. The few settings needed by MS-DOS were stored in the plain text file CONFIG.SYS. DOS programs had to make their own arrangements for storing user settings.

Windows originally used INI files - text files organised in a simple format that could be read and written using special routines available to Windows programs. Windows had one configuration file, SYSTEM.INI, which was used for all the internal settings plus another, WIN.INI, for user preferences. Each application had an INI file, too, usually named after itself.

This system worked pretty well, and is still used by some Windows programs, but it turned out to have a few disadvantages. INI files were slow to access and limited in size to 64Kb. There was also just one INI file per program per computer, making it difficult to have different settings for each user of a computer.

So for Windows NT and Windows 95 Microsoft introduced the Registry. You can think of the Registry as a database for storing and accessing configuration data. Like all good databases the Registry can store different types of data. It is organised for fast and efficient access. Data is stored in a hierarchical manner rather like the folders on a hard disk. Registry data that is currently in use is cached in memory to provide better performance.

A Computer Registry--that is synonymous with Windows Registry--creates a database of information about all hardware, software, devices and programs installed on the computer. It is a repository of information about the computer's configuration. It tracks any changes made to the settings.

Computer registry should not be edited manually. However when you observe any of the following errors, the registry would need a clean up:

The speed of the computer is not the same as it used to be earlier.

The computer faces frequent crash though there is no error or problem.

The system does not start or shut down normally.

It prevents addition or deletion of software.

The computer screen turns blue and you are unable to access any controls

This article describes the registry. This article also includes information about how to back up the registry, how to edit the ...

This is a preview of the whole essay

Computer registry should not be edited manually. However when you observe any of the following errors, the registry would need a clean up:

The speed of the computer is not the same as it used to be earlier.

The computer faces frequent crash though there is no error or problem.

The system does not start or shut down normally.

It prevents addition or deletion of software.

The computer screen turns blue and you are unable to access any controls

This article describes the registry. This article also includes information about how to back up the registry, how to edit the registry, and lists references for more information.

Description of the registry

The Microsoft Computer Dictionary, Fifth Edition, defines the registry as:

A central hierarchical database used in Microsoft Windows 98, Windows CE, Windows NT, and Windows 2000 used to store information that is necessary to configure the system for one or more users, applications and hardware devices.

The Registry contains information that Windows continually references during operation, such as profiles for each user, the applications installed on the computer and the types of documents that each can create, property sheet settings for folders and application icons, what hardware exists on the system, and the ports that are being used.

The Registry replaces most of the text-based .ini files that are used in Windows 3.x and MS-DOS configuration files, such as the Autoexec.bat and Config.sys. Although the Registry is common to several Windows operating systems, there are some differences among them.

A registry hive is a group of keys, subkeys, and values in the registry that has a set of supporting files that contain backups of its data. The supporting files for all hives except HKEY_CURRENT_USER are in the %SystemRoot%\System32\Config folder on Windows NT 4.0, Windows 2000, Windows XP, Windows Server 2003, and Windows Vista. The supporting files for HKEY_CURRENT_USER are in the %SystemRoot%\Profiles\Username folder. The file name extensions of the files in these folders indicate the type of data that they contain. Also, the lack of an extension may sometimes indicate the type of data that they contain.

In Windows 98, the registry files are named User.dat and System.dat. In Windows Millennium Edition, the registry files are named Classes.dat, User.dat, and System.dat.

Note Security features in Windows NT, Windows 2000, Windows XP, Windows Server 2003, and Windows Vista let an administrator control access to registry keys.

The following table lists the predefined keys that are used by the system. The maximum size of a key name is 255 characters.

Note The registry in 64-bit versions of Windows XP, Windows Server 2003, and Windows Vista is divided into 32-bit and 64-bit keys. Many of the 32-bit keys have the same names as their 64-bit counterparts, and vice versa. The default 64-bit version of Registry Editor that is included with 64-bit versions of Windows XP, Windows Server 2003, and Windows Vista displays the 32-bit keys under the following node:

HKEY_LOCAL_MACHINE\Software\WOW6432Node

For more information about how to view the registry on 64-Bit versions of Windows, click the following article number to view the article in the Microsoft Knowledge Base:

How to view the system registry by using 64-bit versions of Windows

The following table lists the data types that are currently defined and that are used by Windows. The maximum size of a value name is as follows:

Windows Server 2003, Windows XP, and Windows Vista: 16,383 characters
Windows 2000: 260 ANSI characters or 16,383 Unicode characters
Windows Millennium Edition/Windows 98/Windows 95: 255 characters

Long values (more than 2,048 bytes) must be stored as files with the file names stored in the registry. This helps the registry perform efficiently. The maximum size of a value is as follows:

Windows NT 4.0/Windows 2000/Windows XP/Windows Server 2003/Windows Vista: Available memory
Windows Millennium Edition/Windows 98/Windows 95: 16,300 bytes

Note There is a 64K limit for the total size of all values of a key.

Back up the registry

Before you edit the registry, export the keys in the registry that you plan to edit, or back up the whole registry. If a problem occurs, you can then follow the steps in the "Restore the registry" section to restore the registry to its previous state. To back up the whole registry, use the Backup utility to back up the system state. The system state includes the registry, the COM+ Class Registration Database, and your boot files. For more information about how to use the Backup utility to back up the system state, click the following article numbers to view the articles in the Microsoft Knowledge Base:

How to use the Backup utility that is included in Windows XP to back up files and folders

How to use the Backup utility to back up files and folders in Windows XP Home Edition

How to use the backup feature to back up and restore data in Windows Server 2003

Edit the registry

To modify registry data, a program must use the registry functions that are defined in the following MSDN Web site:

Administrators can modify the registry by using Registry Editor (Regedit.exe or Regedt32.exe), Group Policy, System Policy, Registry (.reg) files, or by running scripts such as VisualBasic script files.

Use the Windows user interface

We recommend that you use the Windows user interface to change your system settings instead of manually editing the registry. However, editing the registry may sometimes be the best method to resolve a product issue. If the issue is documented in the Microsoft Knowledge Base, an article with step-by-step instructions to edit the registry for that issue will be available. We recommend that you follow those instructions exactly.

Use Registry Editor

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall the operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.
You can use Registry Editor to do the following:

Locate a subtree, key, subkey, or value
Add a subkey or a value
Change a value
Delete a subkey or a value
Rename a subkey or a value

The navigation area of Registry Editor displays folders. Each folder represents a predefined key on the local computer. When you access the registry of a remote computer, only two predefined keys appear: HKEY_USERS and HKEY_LOCAL_MACHINE.

Use Group Policy

Microsoft Management Console (MMC) hosts administrative tools that you can use to administer networks, computers, services, and other system components. The Group Policy MMC snap-in lets administrators define policy settings that are applied to computers or users. You can implement Group Policy on local computers by using the local Group Policy MMC snap-in, Gpedit.msc. You can implement Group Policy in Active Directory by using the Active Directory Users and Computers MMC snap-in. For more information about how to use Group Policy, see the Help topics in the appropriate Group Policy MMC snap-in.

Use a Registration Entries (.reg) file

Create a Registration Entries (.reg) file that contains the registry changes, and then run the .reg file on the computer where you want to make the changes. You can run the .reg file manually or by using a logon script. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

How to add, modify, or delete registry subkeys and values by using a Registration Entries (.reg) file

Use Windows Script Host

The Windows Script Host lets you run VBScript and JScript scripts directly in the operating system. You can create VBScript and JScript files that use Windows Script Host methods to delete, to read, and to write registry keys and values. For more information about these methods, visit the following Microsoft Web sites:

RegDelete method

RegRead method

RegWrite method

Use Windows Management Instrumentation

Windows Management Instrumentation (WMI) is a component of the Microsoft Windows operating system and is the Microsoft implementation of Web-Based Enterprise Management (WBEM). WBEM is an industry initiative to develop a standard technology for accessing management information in an enterprise environment. You can use WMI to automate administrative tasks (such as editing the registry) in an enterprise environment. You can use WMI in scripting languages that have an engine on Windows and that handle Microsoft ActiveX objects. You can also use the WMI Command-Line utility (Wmic.exe) to modify the Windows registry.
For more information about WMI, visit the following Microsoft Web site:

For more information about the WMI Command-Line utility, click the following article number to view the article in the Microsoft Knowledge Base:

A description of the Windows Management Instrumentation (WMI) command-line utility (Wmic.exe)

Use Console Registry Tool for Windows

You can use the Console Registry Tool for Windows (Reg.exe) to edit the registry. For help with the Reg.exe tool, type reg /? at the Command Prompt, and then click OK.

Restore the registry

To restore the registry, use the appropriate method.

Restore the registry keys

To restore registry subkeys that you exported, double-click the Registration Entries (.reg) file that you saved in the Export registry subkeys section. Or, you can restore the whole registry from a backup. For more information about how to restore the whole registry, see the “Restore the whole registry” section later in this article.

Restore the whole registry

To restore the whole registry, restore the system state from a backup. For more information about how to restore the system state from a backup, click the following article number to view the article in the Microsoft Knowledge Base:

How to use Backup to restore files and folders on your computer in Windows XP

Note Backing up the system state also creates updated copies of the registry files in the %SystemRoot%\Repair folder. If you cannot start Windows XP after you edit the registry, you can replace the registry files manually by using the steps in the "Part One" section of the following Microsoft Knowledge Base article:

How to recover from a corrupted registry that prevents Windows XP from starting

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