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

	    bus = new USB (dir, 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;
	}