INT 7F - Alloy NTNX (Slave) - ALLOCATE FREE CLUSTER ON SHARED DRIVE
        AH = 06h
        DL = drive number (1=A:,2=B:,etc)
        CX = number of clusters to allocate
Return: AH = status
            00h successful
                CX = number of clusters still free
            10h invalid shared drive request
                CL = first and second shared drives
            11h invalid cluster count (must be 01h-FFh)