Function:   GetDrive()

               This function provides some control over the
               Acces of logical drives from DOS. Using GetDrive()
               one can inspect the drive letter that was last to
               access a Drive. Needs DOS 3.20!.

   Syntax:     GetDrive([<nDisk>]) --> nLastAccessed

   Arguments:  <nDisk> is the drive to inspect, 0 or none
               indicates current drive, 1=A: etc.. Note that the
               coding begins with 0 = default and 1=A, contrary
               to some other Disk functions.

   Returns:    a Numeric, 0 if the specified disk drive has only
               One letter assigned to it, if Non Zero, the
               function returns the drive Letter the specified
               drive was last accessed with.

   Usage:      See the SetDrive() example.