The Mac Plus could take a 68020 Accelerator board, and mine came without a co-processor, so... I found a 68882 with a missing pin, and soldered one on. It worked like a charm. Wait... Apple SANE did not come out until the Macintosh II... OH! You made a joke. ok. a Cray-X-MP/48 is a math co-processor for a Macintosh.