to configure the network controller for the proper mode of operation for example the controller is configured to a specific mac address and setup to operate in a promiscuous manner where all incoming packets are passed to the interface board 30 additionally the controller is configured to contain a particular size of receive and transmit buffer fig4 shows another embodiment of the interface board 30 in this embodiment each of the connectors 40 42 and 44 are the same as already described additionally the physical layer network controller 46 and the control and buffering 62 are the same as previously described a switch 70 is coupled between the network controller 46 and the emulator connector 42 the switch 70 has three data terminals 72 74 76 and a control input 78 the switch 70 is bidirectional so that terminal 76 is either electrically coupled to terminal 72 or terminal 74 more specifically the switch 70 either electrically couples the network controller 46 to the emulator connector 42 or electrically couples the control and buffering 62 and the emulator connector 42 thus in one mode of operation with terminals 74 and 76 electrically connected the emulator 12 is electrically connected to the network 33 and can receive and send packets to the active or live network in a second mode of operation the terminals 72 and 76 are electrically connected and the network is electrically disconnected.