The Windows Registry

The Windows Registry

Windows 3 .x is a virtual forest of INI files that contain the configuration and execution instructions for Windows and its installed applications, but beginning with Windows 95, a lot of this information has been consolidated into the Registry. Windows 3 .x and Windows NT had perfunctory registries in a file named REG.DAT. The Windows 9 x and Windows 2000 Registry is a special hierarchical database that contains a complete profile of the system configuration and program settings, eliminating the need for most of the INI files.

The Registry records the overall hardware and software configuration and associations of the Windows system. Expect to see at least three or four test questions about the Windows Registry. The questions do not drill down to a specific Windows version and are very generic, recognizing that at PC repairperson should not necessarily be mucking about in the Registry.

Know these facts about the Registry:

l The two Registry files are USER.DAT and SYSTEM.DAT.

l The file extension for backups of the Registry files is .DA0.

l The acronym HKEY stands for Handle for a Key.

l If you export part of all of the Registry to back it up, the exported data is placed in a file with a .REG extension.

l The Registry is organized in a tree hierarchy around six major keys. Each key is a major branch of the registry database and holds information relating to the subject of the branch.

The six major keys of the Windows Registry are the following:

l HKEY_CLASSES_ROOT: File associations and OLE (Object Linking and Embedding) data.

l HKEY_USERS: User preferences, including desktop setup and network connections.

l HKEY_CURRENT_USER: On a PC with only a single user, this key is a duplicate of the HKEY_USERS key. However, on a PC with multiple logins, it contains the preferences of the currently logged-in user.

l HKEY_LOCAL_MACHINE: The hardware and software installed on the system.

l HKEY_CURRENT_CONFIG: In addition to duplicating the KEY_LOCAL_MACHINE key when running, this key also contains any configuration changes made in the current session and information on the printers and fonts installed.

l HKEY_DYN_DATA: Records system performance information and keeps information on Plug and Play devices.

Time Shaver You need to know that the Registry is organized into keys and the contents of each key.

Editing the Registry, if you dare

Use the REGEDIT.EXE program to edit Registry files. Make changes to the Registry only with extreme caution and care. Be sure that you back up both the SYSTEM.DAT and the USER.DAT files before making any changes to the Registry. You may want to back up these files before you install new.