9:04:07beachfrodef: Multics did not use the idea that every user has a virtual computer, at least not in the sense of a linear address space starting at 0. Multics used "segments" that were fixed-size arrays and that were pages. A Multics virtual address was a pair [segment-number,offset]. Unix, on the other hand did use that idea. Probably because they had to. The first computers it ran on, did not have a memory management unit.
9:06:47beachfrodef: But, yeah, Multics used processes to separate users from one another. Virtual addresses were 18+18 bits, so there were not enough addresses for everyone to share the same address space. Therefore, virtual addresses were not valid across process boundaries, just like with Unix.