Microsoft Windows Registry

Registry basics
The registry contains extended information, settings, and various other values for the the Microsoft Windows 95, Windows 98, Windows NT, Windows 2000, Windows ME, Windows XP Operating Systems. Within the registry you can control a great majority of the operating system as well as fix a lot of issues with Windows. However, we only recommend those who are experienced with computers or who feel confident to go into the registry.
Before going into the Registry and changing or deleting anything, we ALWAYS recommend that you backup the registry.
The computer registry consists of two files hidden in the Windows directory, system.dat and user.dat. User-specific system information is contained in the user.dat file and Computer and Hardware specific information in the system.dat file.
To get into the Windows 95 or Windows 98 registry, click Start / Run / type regedit

When typing regedit you will get the below screen; this window, as you can see, is the Registry editor. This windows looks very similar to Explorer; however, within each folder you have sub folders that have various settings.
Below are the objects you find in the Windows registry.
- Open or selected folder just as you would see in Windows Explorer
- Closed folder just as you would see in Windows Explorer
- String Value allows you to place certain values to certain aspects of a program such as a version number.
- Binary Value allows you to set attributes to a particular application, values are in binary.
- Dword Similar to the binary value allowing you to set attributes; however, are done in binary and hex.

Backing up the Windows 95 registry

To backup the Windows 95 registry, manually restart the computer in MS-DOS prompt.

Type cd\windows

At the C:\Windows> prompt, type the following:

attrib user.dat -r -a -s -h <press enter>
attrib system.dat -r -a -s -h <press enter>
md backup <press enter>
copy user.dat backup <press enter>
copy system.dat backup <press enter>

The above will copy the registry files into a backup directory in your Windows directory. This directory can be substituted for any directory or any other drive. Note: In many cases, the registry cannot be copied onto a single floppy because it exceeds the size of a standard floppy.

Restoring the Windows 95 registry

If you have made a backup of the user.dat and system.dat files in the past and you have verified they still exist, follow the below steps to restore your Windows 95 registry.

First, get the computer to a MS-DOS prompt.

Once at the MS-DOS prompt, type cd\windows 

Once in the Windows directory, type the following:

attrib user.dat -r -a -s -h <press enter>
attrib system.dat -r -a -s -h <press enter>
del user.dat <press enter>
del system.dat <press enter>

Once these files have been deleted, type cd\windows\backup once in the windows\backup directory type the below. If you have have changed the location of where your registry is backed up you will need to change to the directory that contains the backup.

copy user.dat c:\windows <press enter>
copy system.dat c:\windows <press enter>

The above should copy two files; once copied, reboot the computer and you should now be able to get back into Windows.

Backing up the Windows 98 registry

Windows 98 has a new utility known as 'scanreg', this utility automatically makes backups of your registry each time you boot up your computer. However, the steps listed above for backing up Windows 95 registry also work but are not necessarily needed unless you wish to keep an original elsewhere.

Restoring Windows 98 registry

To restore Windows 98 registry, open a MS-DOS prompt.

At the MS-DOS prompt, type cd\windows\command

Once in this directory, type scanreg /restore this will restore an earlier version of your registry. Once completed, reboot the computer and this should resolve any issues that may have occurred with your registry.

If you backed up your registry using the Windows 95 steps use the Windows 95 restore steps to restore the registry.

Backing up the Windows ME registry

Like its predecessor, Microsoft Windows ME also includes the scanreg utility. This utility automatically makes backups of the registry each time the computer boots.

Restoring the Windows ME registry

To restore an earlier version of the registry a user can click Start, Run, and type scanreg /restore to restore the registry. If you are unable to get into Windows this can also be done through Windows Safe Mode.

Backing up the Windows 2000 registry

The Microsoft Windows 2000 registry can be backed up easily from the backup utility by following the below steps.

1. Click Start, Programs, Accessories, and click backup.
2. Within backup, click the backup tab.
3. Within the backup tab, check "System State", this will create a backup of boot files, COM+ Class Registry Database, and the system registry.

Restoring the Windows 2000 registry

If you have created backups using the Microsoft backup utility from the backup utility you can also restore the registry through this utility.

Backing up the Windows XP registry

Microsoft Windows XP includes a new feature known as system restore. This great new feature enables a user to backup and restore their important system files from an earlier day. By default this feature automatically creates a backup of the system each day. If you wish to create a restore point of your system follow the below steps.

1. Click Start, Programs, Accessories, System Tools, System Restore
2. Select the option to Create a restore point
3. Click next and follow the remainder steps.

Restoring the Windows XP registry

To restore the system back to an earlier point follow the below steps.

1. Click Start, Programs, Accessories, System Tools, System Restore
2. Select the Restore my computer to an earlier time option and click next
3. Select the day and the restore point you wish to restore and click next.

Registry keys

KEY	DESCRIPTION
HKEY_CLASSES_ROOT	Points to branch of Hkey_Local_Machine that describes certain software settings. This key displays the same data as it did in Windows 3.1 - essential information about OLE and association mappings to support drag-and-drop operations, Windows 95 shortcuts (which are, in fact, OLE links), and core aspects of the Windows 95 user interface.
HKEY_CURRENT_USER	This key points to a branch of Hkey_Users for the user who is currently logged on.
HKEY_LOCAL_MACHINE	Contains computer-specific information about the hardware installed, software settings, and other information. This information is used for all users who log on to this computer.
HKEY_USERS	Contains information about all the users who log on to the computer, including both generic and user-specific information. The generic settings are available to all users who log on to the computer. The information is made up of default settings for applications, desktop configurations, and so on. This key contains sub keys for each user that logs on to this computer.
HKEY_CURRENT_CONFIG	Points to a branch of Hkey_Local_Machine\Config that contains information about the current configuration of hardware attached to the computer.
HKEY_DYN_DATA	Points to a branch of Hkey_Local_Machine that contains the dynamic status information for various devices as part of the Plug and Play information. This information may change as devices are added to or removed from the computer. The information for each device includes the related hardware key and the device's current status, including problems.

Registry screen shots

The Main Windows of the Registry Editor