The part number (21-01170-01) is from Digital Equipment Corporation (DEC), which had factories near to the item's location, in Maynard and Marlborough, Mass. I have not seen that part before, and it doesn't appear to be indexed by G**gle anywhere.
My wild-ass-guess would be that it has something to do with the VAX 9000 (Aquarius), which was a VAX supercomputer with vector extensions. The mezzanine connector looks like a FCI Meg-Array 10022671. These chips are probably not usable by breaking bond wires due to rough handling.
Incidentally, your "divide by cucumber error" sig is relevant to DEC microcircuits. The engineers there published a joke paper about "organic light emitting materials" in which they stuck electrodes into a pickle. That inside joke became the code number for Alpha CPUs, which were numbered EVxx for "Electro Vlasic" (Vlasic is a brand of pickle). EV also could stand for "Extended VAX", but the joke explanation for the name was preferred.