When calling the COBOL library routine PC_READ_DRIVE the drive letter is sometimes returned in upper-case while other times it is returned in lower-case.  How can I make this consistent so that the drive letter can successfully be used in comparisons?

This is actually a Windows issue in that the underlying API call can return the drive in either upper-case or lower-case depending opn how the system was setup and some other factors.

To ensure consistency in your application please use the appropriate intrinsic function to convert the drive letter returned to either upper-case or lower-case as show below:

MOVE FUNCTION UPPER-CASE(DRIVE) to DRIVE