Drive Letter Assignment

The Windows Assigned Drive Letter

When a USB drive is plugged into a computer Windows assigns the drive a drive letter. The drive letter used may change from one computer to the next. The Windows assigned drive letter can even change on the same computer between sessions. The variability of the drive's assigned letter is an issue for non-portable apps since those apps assume the letter of the drive they are running from never changes, and they tend to form dependencies based on that assumption.

The App Briefcase Assigned Drive Letter

App Briefcase resolves the issue of a USB drive's varying drive letter by assigning a second drive letter to the drive. App Briefcase assigns the same second drive letter every time App Briefcase is started. Note the Windows assigned drive letter and the App Briefcase assigned drive letter both refer to the same physical USB drive! The App Briefcase assigned drive letter is a temporary assignment which is removed when App Briefcase exits.

You should always use the App Briefcase assigned drive letter, rather than the Windows assigned drive letter, while using your portable USB drive. For example, if App Briefcase assigns drive letter M to the USB drive then you should always install new apps to drive M, always open files from drive M, and always save files to drive M. Consistent use of the App Briefcase assigned drive letter instead of the Windows assigned drive letter ensures the apps installed on the USB drive are always working with a stable drive letter.

Changing the App Briefcase Assigned Drive Letter

The App Briefcase assigned drive letter is chosen by you the first time you run App Briefcase. The App Briefcase assigned drive letter can be changed in the Options window. However, it is recommended that you do not change the App Briefcase assigned drive letter after you have begun installing apps using the letter since doing so can cause drive letter confusion for those apps.