Abstract: A system (such as a multiprotocol LAN adapter) for use in a workstation or other processing machine automatically determines the type of network to which the workstation is connected and for automatically determines the type of physical medium to which the workstation is attached. The system has a plurality of different physical ports for supporting various available physical media over which network data may be transmitted. For example, the system may have a port for connecting to shielded twisted pair (STP) wiring, a port for connecting to unshielded twisted pair (UTP) wiring, a port for connecting to coaxial cable, and a port for supporting the Attachment Unit Interface (AUI). Connected to each of these physical ports are various network interface devices for supporting the various available networking protocols, e.g., token ring, Ethernet, etc. Logic circuitry and control software are connected to the network interface devices.