The SUPERNET 3 is backward compatible to the SUPERNET 2 Tag Mode of operation in which the SUPERNET 3 buffer memory interface logic maintains the buffer memory as multiple FIFOs. The SUPERNET 3 provides DMA channels, arbitrates access to the network buffer memory, and controls the data path between the buffer memory and the medium. The MAC also implements the timed-token protocol and receive/transmit control as specified for the Media Access Control (MAC) sublayer of the ISO standard 9314-2 for FDDI. The Physical Layer functions defined by the ISO 9314-1 are performed by the SUPERNET 3. SUPERNET 3 implements on-chip digital clock recovery and transmit functions for fiber. To support copper media, the PHY-PMD interface is maintained and an external module can be implemented in the same footprint as the fiber optic transceiver to perform the MLT-3 encoding/decoding and equalization. SUPERNET 3 integrates the scrambler and descrambler functions for transmissions over copper media.