Boot ROM for network card

How does a boot ROM for a network card work? ie. how does it boot up and what happens in the process?

Gee, don't people around here help others out? Art there really no one who can give me a general view of how a boot ROM for a NIC works?

Boot ROMs are options to be installed on the network adapters's on-board remote boot socket. They contain boot programs that permit diskless workstations to boot from a boot server. Network administrators can set up a network security scheme by pre-defining a password, a boot volume and the boot volume's content for each workstation.
Etherboot is software you can use to create your own boot rom.