So I commented on this a bit elsewhere, but the whole object business is irrelevant for how the address translation hardware in this machine actually works. While the subfields of the address are exploited to optimize hash function used, the hardware is otherwise agnostic to what the upper bits of the address mean. The TLB is just huge relative to the amount of memory it had such that there's one entry for each physical page in the system and it deals with collisions in the TLB by evicting pages to disk