In Appendix C, “Per-
is similar to
. In fact, the organization of this key is almost identical. The difference is that these settings are computer-oriented; they affect every user who logs on to the computer. However, you find some settings in both places,
. This is common with Microsoft Office 2003 Editions and many of the policies in Windows, for example. Most often, when a setting is in both places, the version in
has precedence over the same setting in
. Only when an administrator
Other branches in
are unique, though. Windows stores the computer's configuration in
. The operating system's lower-level settings are in this branch, too. Lower-level settings include the configuration of the computer's network connections, device drivers, services, and so on. Windows also stores local security data in
. Something else unique in
is that it contains more links than
does. Recall that links are aliases for other subkeys, and Windows uses links in
to support features such as hardware profiles and configuration sets. This appendix describes these links so that you can better understand how different
This appendix outlines the organization of HKLM , describing its interesting and useful subkeys. But by no means do I cover this root key's entire contents. Instead, I've focused on settings that you're most likely to customize or need to understand as a power user or IT professional. Also, I don't describe the hive files or how Windows loads them into HKLM because Chapter 1, “Learning the Basics,” already covers this.
every time the operating system starts. This key contains configuration data that the operating system detects when it starts. This branch contains few values to customize because the branch's contents are volatile. Some values in it are useful for
The following list is an overview of the HARDWARE key's subkeys, and the sections following this one give more details about some of them:
Each time Windows boots, its hardware recognizer collects information about the computer's hardware and stores it in HKLM\HARDWARE\DESCRIPTION\System . In this branch, you find three subkeys:
The DEVICEMAP subkey is another interesting subkey of HKLM\HARDWARE . It maps the devices that the hardware recognizer detects to the services that drive them. Different device classes have different subkeys in D EVICEMAP . For example, this subkey typically contains the subkeys KeyboardClass and PointerClass . You don't find subkeys for every device in the computer, though. It contains subkeys only for those devices that Windows requires to start the computer. Thus, you don't find subkeys for sound cards and the like.
These subkeys contain one or more values. The values' names are the devices'