only things I can think of of the top of my head that used these 15-pin D-Sub connectors are AUI (a very early Ethernet format), PC Game Port, and possibly a few non-PC RGB connections...
other intriguing things on this card...
the POT near the bottom for selecting/adjusting something (network address? just assuming AUI, here)
2 spots for what look like crystal oscillators (DIL-14), with a jumper next to each (removed if you solder a crystal in place, I suppose)
a teeny tiny battery in the top right to provide a trickle charge for when the machine is off.... for something... (the network address? but wouldn't a jumper(s) simply suffice...)
it's an odd one...
Copyright (C) Digital Art System 199(0 or 3) by EFK