Messages in this thread | | | Date | Mon, 28 Aug 2000 17:13:41 -0600 | From | yodaiken@fsmlabs ... | Subject | Re: SCO: "thread creation is about a thousand times faster than on |
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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
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