The Device Manager uses and manages several registry keys under the HKEY_LOCAL_MACHINE\Drivers\ key to load, track, and unload linear block device drivers. Built-in devices, such as the DiskOnChip, rely on the registry settings to be present at boot time; therefore, these keys must be part of the default registry. However, you can install keys for removable block devices, such as linear flash memory PC Cards, upon first use of the device.