This particular board allows Apple computers to be part of a token ring network. The token ring network architecture is an alternative to networks based on TCP/IP. Token ring systems pass around a specialized series of bytes (tokens) in a round-robin fashion to all machines within a network. This ensures that all machines on this network will have at least some guaranteed portion of network bandwidth, a property of great importance in real-time control applications (manufacturing, for example). The token ring architecture was invented by IBM and is still in broad use today. NuBus card. Worked when removed from equipment.