a semiconductor wafer has a plurality of holes therein which correspond to pins of an electrical connector . the wafer includes circuitry thereon and contacts for making electrical connection to the pins . in such manner , the circuitry on the wafer can be used for a wide variety of purposes such as testing or modifying signals carried by the pins . the wafer can be installed in any common electrical connector pair without prior modification or preparation of the connectors and without impairing the normal fit or function of the mated connector pair .