[pups] PDP-9?

Warren Toomey wkt at minnie.tuhs.org
Mon Sep 2 18:00:35 AEST 2002

In article by Fred N. van Kempen:
> Unix was _developed_ on the 11/20.  The first versions (up to  the
> fourth or fifth edition or so) didn't require an MMU, and, therfore,
> had no protection whatsoever.
> Dennis... tell us the "All out?" story.. please.. :)
> --fred

Was it this story (from http://cm.bell-labs.com/cm/cs/who/dmr/odd.html):

Back around 1970-71, Unix on the PDP-11/20 ran on hardware that
not only did not support virtual memory, but didn't support any
kind of hardware memory mapping or protection, for example against
writing over the kernel. This was a pain, because we were using
the machine for multiple users. When anyone was working on a program,
it was considered a courtesy to yell "A.OUT?" before trying it, to
warn others to save whatever they were editing.

[A substory: at some point several were sitting around working
away. Bob Morris asked, almost conversationally, "what are the
arguments to ld?" Someone told him. We continued typing for the
next minute, as a thought began to percolate, not quite to the top
of the brain - in other words, not quite fast enough. The terminal
stopped echoing before anyone could stop and say "Hold on Bob, what
is it you're trying to do?"]


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