[TUHS] advent of "modern" Unix OS

[Paul Winalski via TUHS]

On Sun, Apr 26, 2026 at 3:04 AM Lars Brinkhoff via TUHS <tuhs at tuhs.org>
wrote:

> John Cowan wrote:
> > Larry McVoy wrote:
>
>> Mojo did the VM system that gave us the first version of mmap() (that
> >> I'm aware of, maybe Multics had one?).
> > In Multics it was all mmap()
>
> And in between, TENEX had PMAP.  I have seen a claim that Berkeley's
> mmap was essentially modeled on PMAP.
>

VAX/VMS allowed memory mapping of files via the $CRMPSC (create and map
section) system service.  This is the general system call to create virtual
address space, either read-write or read-only.  By default the backing
store for the VM is the paging file but you can specify any arbitrary file
as backing store, thus memory mapping that file.  The design work for this
feature would have been done ca. 1975.

-Paul W.