Abstract: A terminal controller system is described wherein several feature cards are plugged into slots on a board, and I/O signal cables are connected between cards and/or remote multiplexors or terminals. A special purpose card identification (ID) bus is driven by the feature cards and received by an ID adapter. The ID adapter has one select line running to each of the slots on the board. The ID adapter enables the select lines one at a time, whereby the selected feature cards drive their IDs onto the ID bus. A processor records the slot population by ID and also can analyze the IDs to determine if a valid configuration exists. The processor then performs a wrap test on each of its ports. This test alters the ID which it wraps and by comparison with the IDs recorded originally, this enables the processor to logically establish the physical link to particular cards connected to the ports.