Hehe, I think the "Ethernet" part in that last picture is a big clue
Although that wasn't really necessary; the coax wiring in the first picture is typically thin Ethernet, and the other connector looks like AUI, pointing heavily toward Ethernet as well.
The presence of the DP8390 controller in the first & second pictures is the definitive answer: it's an old Ethernet (10base2 & AUI) card.
if it was designed the same as all the others DP8390-based devices with an appropriate Declaration Rom, then it should work without additional software in 7.1+ I think (definitely in 7.5+).