On Mon, Aug 28, 2000 at 07:16:34PM -0400, Alexander Viro wrote:
> > > Funny. I didn't know that -11/20 had memory protection...
> >
> > PDP-11 had good memory protection. I think PDP 8 may even have had it.
> > None of this newfangled paging b.s. though.
>
> I think you are mixing -11/20 with -11/45... (-8 is completely irrelevant
> and I don't know whether there was any memory protection on -{7,9}, but I
> really doubt it).
I think the 11/20 had an optional MMU, but I'm not sure. I have a vague
memory that the 8 had a map register, but that may be totally wrong.
UNIX as a useful OS begins with V6 which ran on the 11/40 and
up and these, for sure, had segments. Even V5 needed an 11/40.
See sheets 16 & 17 in the Lions book.
But I'd love to see a reasonable argument as to why fork/exec would be useful
on an mmu-less processor in the current state of the field.
90% of the semantics disappear.
-- --------------------------------------------------------- Victor Yodaiken Finite State Machine Labs: The RTLinux Company. www.fsmlabs.com www.rtlinux.com- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/
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