The Registry key UserDriveLetterAssignment (located in HKEY_LOCAL_MACHINE\Enum\…) lets the user, via System Properties / Device Manager / Properties / Settings, lets the user specify a range of drive letters that will be reserved for each removable media drive during system initialization. If not specified by the user, the number of drive letters to be assigned will be based on the number of partitions on the media currently present at boot time. If the drive range is not specified by the user and no media is present at boot time then Windows 95 reserves 1 drive letter for each removable media.