It appears that Lars Brinkhoff <lars(a)nocrew.org> said:
G. Branden Robinson wrote:
well after Unix had fledged, its developers at
CSRC found it necessary
and/or desirable to borrow back a Multics concept: they named it mmap().
It has been argued the borrowing was from TENEX. TENEX in turn would
have been influenced by Multics and the SDS 940 timesharing system.
mmap() is a lot more like Tenex than it is like Multics. Tenex ran
on a PDP-10 with a flat 18 bit address space, and you could map files
to places in that address space. It didn't have any of the Multics
segment stuff where a process was a collection of segments and you
made a segment addressable which implicitly mapped the whole segment.