There is disclosed an apparatus for controlling a physical layer interface of a network interface card. The apparatus comprises: 1) a read only memory (ROM) for storing an embedded control program; 2) a random access memory for storing a downloadable software control program; and 3) a microcontroller for controlling the physical layer interface, wherein the microcontroller in a first operating mode executes the embedded control program to thereby control the physical layer interface, and wherein the microcontroller in a second operating mode downloads the downloadable software control program from an external processing system and executes the software control program in place of the embedded control program to thereby control the physical layer interface.