Avid / E3 Engine / Internals
The Avid:E3 Engine contains a daughter board (the Diamond Platform controller) running Linux that enables the AVB protocol stack, and connects to the physical audio interfaces of the E3 engine. The fourth Ethernet port is controlled by Windows.
It also contains a second daughter board (the Feroceon-KW controller) running Linux that enables the Ethernet switching functionality of the AVB ports. It also provides an EUCON proxy for connecting to the S3 console.
This is a rough block diagram of the Avid:E3 Engine:Internals based on my current understanding from my digging.
The Avid:E3 Engine is made up of multiple embedded controllers.