For certain, ILLIAC, but the 6500 was 2 6400 CPUs
sharing a common
memory and PPU set. ?Doubtless there were other 60's era machines to
do the same, but no others readily come to mind.
I bet Babbage and Zuse also thought the same thing. Anyway, I think
Burroughs the was "first" to get real SMP, with the B5500.
--
Will