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Date: Fri, 10 Nov 1995 08:46:36 -0800
From: "Steven M. Schultz" <sms@wlv.iipo.gtegsc.com>
Message-Id: <199511101646.IAA18106@wlv.iipo.gtegsc.com>
To: oldunix@minnie.cs.adfa.oz.au, rjm@swift.eng.ox.ac.uk
Subject: Re: Which versions for 11/34 (Sep I+D space)

Bob -

> From: rjm@swift.eng.ox.ac.uk (Bob Manners)
> 
> It has been suggested to me that since the 11/34a MMU doesn't support
> separate instruction and data space, certain versions of UNIX are not
> suitable. Does anyone out there have any idea which versions of UNIX
> require separate I+D space?

	The last version of UNIX for the PDP11 which stood a chance of
	running on a non split machine was 2.9BSD.  I'd expect it to be
	a very tight fit though because even on a split I/D machine we
	ended up overlaying the kernel (but then even V7 took overlays
	to fit - which we hacked into the kernel, at least in the environment 
	here).  A long long time ago I did squish a V7 system into an 11/23 - 
	not a pretty sight, each command you ran caused the others on the 
	system to be swapped out (do a "ls -l" and watch the shell get swapped,
	when the 'ls' finished then the shell would be swapped back in, etc.)

	V6 would be a better match for a non-split (248kb max) machine.  By
	the time V7 was out the 11/70 was being used as the development 
	platform and split I/D was becoming more and more necessary.

	Steven Schultz
	sms@wlv.iipo.gtegsc.com