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From: john@frog.UUCP
Newsgroups: comp.sys.dec
Subject: Re: UNIX on a PDP11
Message-ID: <1299@frog.UUCP>
Date: Mon, 23-Mar-87 15:49:00 EST
Article-I.D.: frog.1299
Posted: Mon Mar 23 15:49:00 1987
Date-Received: Wed, 25-Mar-87 06:17:04 EST
References: <1741@a.cs.okstate.edu> <3335@ihlpa.ATT.COM>
Organization: Superfrog Heaven [ CRDS, Framingham MA ]
Lines: 45

In some article, someone answers:
> In article <1741@a.cs.okstate.edu>, chris@a.cs.okstate.edu (Chris Schuermann) writes:
> > I have recently acquired 2 PDP11/34s....upgraded to 11/40s.
with:
> 
> ...The 11/40 is a vintage PDP (ie Unibus), it has very little capability
> for virtual memory, only an 18 bit address bus...
> 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
> 
> The RK05's are 2.5Mbyte drives...to run a modern version of Un*x it would
> take a couple of these.
> 
> 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

In the words of Zero Mostel, "Say OOPS and get out!" (The Producers).  The
11/34 is definitely a UNIBUS machine (according to my 1978/79 copy of the
"pdp11/04/34/45/55/60 processor handbook", and according to the 11/34 I used
at MIT), and since it is neither an /04 (oh-four) nor a /20, it has an 18-bit
physical address space (and 16-bit virtual address space, like any other
PDP-11).  I don't remember what the /40 (forty) is, but I seem to recall that
the /34 is basically a new-technology /40.

UNIX runs on the /34, but it's a tight fit.  Get 2.8BSD/2.9BSD if you can,
it has overlays to use up memory at incredible rates :-).

What the respondant may have been thinking of is the 11/04 (a new-technology
/20, and thus quite crippled), and the 11/23 (such as I have at home), which
is, indeed a QBUS machine that, if you have the 11/23+ and not the bare 11/23
(such as I have at home :-( ), has a 22-bit physical address space (the bare
11/23 has only 18).

The RK05 is, indeed, a 2,457,600 byte cartridge.  It makes a perfectly
adequate backup UNIX root for mitccc's PDP-11/70 (and seems perfectly
miniscule compared to our two 300Mb drives :-).


--
John Woods, Charles River Data Systems, Framingham MA, (617) 626-1101
...!decvax!frog!john, ...!mit-eddie!jfw, jfw%mit-ccc@MIT-XX.ARPA

"Happiness is the planet Earth
	in your rear-view mirror."
		- Sam Hurt, in "Eyebeam, Therefore I Am"