protected void mkBus (String busname, int busnum)
        throws IOException, SecurityException
        {
            USB  bus;

            bus = new USB (directory_prefix, busname, busnum, listeners, self);
            if (trace)
                System.err.println ("mkBus " + bus);

            busses.put (busname, bus);
            for (int i = 0; i < listeners.size (); i++) {
                USBListener listener;
                listener = (USBListener) listeners.elementAt (i);
                try {
                    listener.busAdded (bus);
                } catch (Exception e) {
                    e.printStackTrace ();
                }
            }

            /*  while (bus.scanBus ())
                  continue;*/
        }