Re: SCO: "thread creation is about a thousand times faster than on

Date: Mon Aug 28 2000 - 18:13:41 EST

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.

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