The PE-SMII pack provides a Serial MII Interface for a 10/100 Mbps Ethernet MAC to be used with PHYs that offer two pins per port. The Ethernet MAC core is also available in the Mentor Graphics Inventra (TM) range of soft cores. The required 2-signal + clock and synchronization interface to the PHY is provided by the PESMII module within the PE-SMII pack. This module performs the conversion of the 4-bit MII data handled by the basic MAC design to/from the serial data format of the Serial-MII interface in both the transmit and the receive directions. The registers within the PHY are read and written through the MAC’s Host Interface.