I don't have any idea what this is but it appears to have Z-8000 CPU+MMU chips. Perhaps an Onyx or S8000 CPU card? I know some folks here are in to that sort of thing. http://www.ebay.com/itm/NOS-Vintage-DSC-MP-4-EPC-Rev-D-K-Expansion-Board-Card-PCB-for-Mini-Computer/152475939021 KJ