Yes perhaps I should have said something stronger than merely 'facilitate' but 'MMU parameters were better for GC' is a long way from the Lisp machine hardware/software mindmeld. It's still, as far as I can tell, pretty much just a MMU, right?
I think the main point was to have a more interactivity friendly GC than otherwise possible. Having the user notice GC pauses on an interactive computer - a tablet - would have been a problem. MCL provided an ephemeral GC using the MMU of the 68020 (external) or 68030/40 (integrated). It dealt with short-lived objects in main memory, avoiding virtual memory activity. A similar level of responsiveness probably was the goal.
On the other hand, the newt (Senior, anyway) was running Dylan on bare metal; you don't need to have fancy-pants LISP-accelerating hardware to do that. You just need to have the intestinal fortitude to write an OS and runtime in something not C :-)
