The LAN91C100FD is designed to facilitate the implementation of first generation Fast Ethernet adapters and connectivity products. For this first generation of products, flexibility dominates over integration. The LAN91C100FD is a digital device that implements the MAC portion of the CSMA/CD protocol at 10 and 100 Mbps, and couples it with a lean and fast data and control path system architecture to ensure the CPU to packet RAM data movement does not cause a bottleneck at 100 Mbps.