Exciting!
It's newer than the A560, so it's not a prototype of that. There's also that mini-DIN connector perpendicular to the RCA jacks. Wonder what it could be?
EDIT: @ tone007
Ah, some quick Googling shows that's an Arcnet controller. An A560-CR (cost-reduced) prototype? Something AppleTalk compatible? Where are the Commodore networking group veterans when you need them?
