The STE100P, also referred to as STEPHY1, is a high performance Fast Ethernet physical layer interface for 10Base-T and 100Base-TX applications. It was designed with advanced CMOS technology to provide a Media Independent Interface (MII) for easy attachment to 10/100 Media Access Controllers (MAC) and a physical media interface for 100Base-TX of IEEE802.3u and 10Base-T of IEEE802.3. The STEPHY1 supports both half-duplex and full-duplex operation, at 10 and 100 Mbps operation. Its operating mode can be set using auto-negotiation, parallel detection or manual control. It also allows for the support of auto-negotiation functions for speed and duplex detection.