INT 21 - Novell NetWare - CONNECTION SERVICES - FILE SERVER CONNECTION
        AH = F1h
        AL = subfunction
            00h attach to file server
                DL = preferred file server (01h-08h)
            01h detach from file server
                DL = connection ID
            02h logout from file server
                DL = connection ID
Return: AL = status
            00h successful
            F8h already attached to server
            F9h connection table full
            FAh no more server slots
            FCh unknown file server
            FEh server bindery locked
            FFh no response from server, or connection does not exist
Note:   these functions are supported by Advanced NetWare 1.0+
SeeAlso: AH=E3h/SF=14h