Matrox card?

I have an old Matrox video card that I can't find out much about. It's actually two cards sandwiched together. It looks vaguely like a VME card but has connectors on the side and not on the edge of the card. The connectors look like S-bus connectors like those used in Sun computers. There is one connector in the middle along one edge and a second identical connector offset to one side. The video connector in on the metal mounting plate on the opposite of the card from the S-bus connectors. It's a 13W3 type connector like those used on many SUN, HP and SGI computers. The card is marked Matrox Electronics Systems SG3-1152B/BASE 0385-06-02 Made in Canada Copyright 1990". The only reference that I could find on the net says "I found an old triple-width, Anybody know any more about it? Joe