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From: normt@ihlpa.ATT.COM (N. R Tiedemann)
Newsgroups: comp.sys.dec
Subject: Re: UNIX on a PDP11
Message-ID: <3335@ihlpa.ATT.COM>
Date: Thu, 19-Mar-87 08:40:25 EST
Article-I.D.: ihlpa.3335
Posted: Thu Mar 19 08:40:25 1987
Date-Received: Sat, 21-Mar-87 04:42:04 EST
References: <1741@a.cs.okstate.edu>
Organization: AT&T Bell Laboratories - Naperville, Illinois
Lines: 38

In article <1741@a.cs.okstate.edu>, chris@a.cs.okstate.edu (Chris Schuermann) writes:
> I have recently acquired 2 PDP11/34s.
> Now, I am in need of some info. From what I can tell, they have
> been upgraded to 11/40s. Is this even possible?? All the drawings
> are for an 11/40.  I have several RK05j HDs (well, they work :-)
> I have no docs at all on the OS (which I am reasonably certain is RSX )
> By now I am sure you can tell that I live in the UN*X world.
> the RK05s or will I have to get something larger. Again an assumption:
> RK05s are 5Meg ?????
> Chris Schuermann

To upgrade an 11/34 to an 11/40 would be a step back in time, and would require
a new backplane, cpu, memory, disk controller, possibly the power supplies
could stay the same, but I doubt it. The 11/40 is a vintage PDP (ie Unibus), it
has very little capability for virtual memory, only an 18 bit address bus, and
the only ones that I know are still around, are in my old lab at the U of Wis.
in Madison, and in the Digital Museum. The 11/34 was (about 1978) the newest
and best Q-bus machine, it does support virtual memory, and will easily run a
multitasking operating system (11/40 will only run RT-11 without a lot of
overhauling). 

The RK05's are 2.5Mbyte drives, (I don't know what the j means), to run a
modern version of Un*x it would take a couple of these. The RK05 and RK06
are the only drives that still support the PDP8 family. (At least that's
what I can find in the DEC catalog.)

So in summary, if they are 11/34's you could run a Un*x, on them. I have
seen Un*x for Q-bus machines, the only problem may be distribution. If
it really is an 11/40 (Unibus) you may have real problems running a "big"
operating system on it. Most software that specs for UNIBUS requires
an 11/70 with its expanded memory capabilities.

	Norm Tiedemann		ihnp4!ihlpa!normt
	AT&T Bell Labs
	Naperville, IL
		 60566

Just because we invented Unix, doesn't mean we have to like it (RT-11 YEH!)