Map A Folder To A Drive Letter Directly In The Registry
This method has a couple of advantages over the Subst command. Not only does it add the mapped drive automatically on every boot, the drive letter is associated with the folder before any applications are launched. That means the drive letter can be used by other applications during boot. This option is not recommended for inexperienced users.
1. Open Regedit and navigate to the following key:
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\DOS Devices
This key will associate virtual drive names with paths and it does so very early in the boot process.
2. Right click on DOS Devices > New > String value, enter the drive letter to map the folder to, including the colon.
3. Double click on the drive letter and enter the following as a path:
4. Close the registry editor and reboot the computer as this key is only read during startup. Upon rebooting, the mapping will show in Explorer in the list of hard drives.
If you decide to create a .REG file to add or edit Dos devices, add a second backslash to every backslash in the folder path. It won’t work otherwise. An example .REG file of the above would be:
Windows Registry Editor Version 5.00
[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Session Manager\DOS Devices]