Configuration and status of the core, including access to and from the optional Auto-Negotiation function, is performed with the 1000BASE-X PCS management registers as defined in IEEE 802.3-2008 clause 37. These registers are accessed through the MDIO, defined in IEEE 802.3-2008 clause 22, as if it were an externally connected PHY.
The PCS management registers can be omitted from the core. In this situation, configuration and status is made possible by using configuration vector and status signals. The configuration interface is provided to program Control register (Register 0) and Auto-Negotiation advertisement register (Register 4) independent of the MDIO interface. Bits corresponding to Remote fault and Pause in Register 5 are also part of Status vector.
When the core is using the SGMII standard, the register information is defined differently. 2500BASE-X uses the same PCS management registers as 1000BASE-X PCS.