One of my Mac IIs came with a portrait display card and a DB13W3 to DB15 cable. I connected it to a High Resolution RGB monitor, but it wasn't recognised by the Mac II (I had two other regular cards in it as well). I'm guessing a portrait card simply can't drive a 640*480 monitor. Is there a way to test it? I haven't tried throwing in a VGA converter into the mix and played with the DIP switches...