The HKEY_LOCAL_MACHINE Key HKEY_LOCAL_MACHINE is one of the most important and most interesting root keys of the registry. It contains configuration data for local computer | The HKEYLOCALMACHINE Key HKEY_LOCAL_MACHINE is one of the most important and most interesting root keys of the registry. It contains configuration data for local computer. Information stored in this registry key is used by applications and device drivers and by the operating system itself for obtaining information on the local computer s configuration. Moreover the information doesn t depend on the user who s logged in to the system. The HKEY_LOCAL_MACHINE root key contains five subkeys briefly described in Table . The rest of this section describes the subkeys in greater detail. Table Subkeys Contained within the HKEY_LOCAL_MACHINE Root Key Subkey Contents HARDWARE This subkey contains a database describing all the hardware devices installed on the computer the method of interaction between device drivers and hardware devices and the data that connects kernel-mode device drivers with user-mode code. All the data contained within this subkey are volatile. The system re-creates these data each time it starts. The Description subkey describes all the hardware physically present on the computer. The hardware recognizer collects this information at system startup and the kernel stores this information under the HKEY_LOCAL_MACHINE HARDWARE DESCRIPTION registry key. The DeviceMap subkey contains various data in formats defined by certain device driver classes. As device drivers are loading they pass their information to the system so that it can associate specific hardware devices and their drivers. HARDWARE The ResourceMap subkey contains information on the system resources allocated to each device including ports DMA addresses IRQs . Notice that all Windows NT-based operating systems including Windows 2000 Windows XP and Windows Server 2003 provide a much more convenient way to view the contents of this subkey. To view and possibly change this data it is recommended that you use various administrative tools. For example if you re using Windows NT you can .
