Configuration and status of the core, including access to and from the optional Auto-Negotiation function, uses the Management registers defined in clause 37 of the IEEE 802.3-2008 Specification [Ref 2] . These registers are accessed through the serial Management Data Input/Output Interface (MDIO), defined in clause 22 of the IEEE 802.3-2008 Specification [Ref 2] , as if it were an externally connected PHY.
An additional configuration vector and status signal interface is provided to configure Base Control register (Register 0) and Auto-Negotiation Ability Advertisement register (Register 4).