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Path: utzoo!linus!philabs!micomvax!musocs!mcgill-vision!mouse
From: mouse@mcgill-vision.UUCP (der Mouse)
Newsgroups: net.decus
Subject: mVAXII vs PDP11/44 comparison?
Message-ID: <153@mcgill-vision.UUCP>
Date: Wed, 25-Sep-85 20:58:02 EDT
Article-I.D.: mcgill-v.153
Posted: Wed Sep 25 20:58:02 1985
Date-Received: Fri, 27-Sep-85 07:31:01 EDT
Organization: McGill University, Montreal
Lines: 99

Apologies to anyone who's seen this before....

Short Version: 
	I am interested in receiving any performance
or compatability comparaisons between a pdp-11/44 running
RSX , used for neurological imaging  and imaging analysis , 
and running a (high end) mVaxII (VMS)- for the same application. 

	a) I/O questions, q-bus vs unibus.
	b) program development.
	c) Unibus peripherals-->Q-bus. Can it be done well ?. 
	etc etc

Note that the applications presently run on a 11/34.
Please email letters or flames or whatever to me at the
following address. Thanks
Sean Marrett

Use the following uucp address..not what the header says.
{..ihnp4,decvax etc}utcsri!mcgill-vision!vnode!webb1
OR
...!philabs!micomvax!musocs!mcgill-vision!etc
From the ARPANET:
(hopefully)
utcsri!mcgill-vision!vnode!webb1@uw-beaver

Long Version:
This is my very first posting. Please be patient with me.
I have recently become responsible for a small computing facility in a
brain imaging center. I am looking for some advice about pdp-11/44, 11/73
vs mVaxII performance and compatability. I will first describe the
problem, then get a bit more specific about what I am after.

	There is a desire and funding (limited) to expand the computing
enviroment, for instance to ease development work. There is 
also no question that *eventually* we will have to
upgrade to a Vax-something ( there are already a few in the institute). 
But the immediate question is whether it is
worth going for a mVaxII now, or to go for a stop-gap pdp-11/44 (actually
an 11/73 acting as an 11/44 emulator). My immediate and almost definite
prejudice, based on a variety of technical and compatability reasons (also
just cuz I HATE to tell someone that, oh yes, I run a few pdp-11's...) is
for the mVaxII. However, I need to be able to back this up on a sound
technical basis....money is not
so easily available that I can go wrong on this question without serious
repercussions. People are willing to be convinced if I can show that a
mVaxII will aid their (neurological) research. Before I forget, I should mention that at present, the
system can support 2 users doing simple PET image analysis...and runs
under RSX-11m.

	There are all sorts of good reasons in terms of compatability with
other facilities in the same group with which we wish to collaborate to
get a Vax, but what I need is good, *HARD* , technical reasons to show
that the mVaxII is worth the extra 30-40K investment NOW (not 1-2 years
from now). I should add that our resources are strained at the moment. The
sorts of questions I THINK i need to address are...

	a) I/O questions, q-bus vs unibus. I have heard rumours of
mVaxII's bogging down under heavy I/O use...I need to make sure this is
is not true. 
	b) program development. Even with an extra 2 meg of memory, and
	the 11/44, how transparent is it to an applications programmer ?
       Ie would a programmer have to use 'virtual arrays etc' to access
       memory or is it real easy to have big arrays etc.
	c) Unibus peripherals-->Q-bus. Can it be done well ?. EG, if we
       have a unibus winchester controller, can I plug it into a
       unibus-qbus adapter and then hang it off the q-bus and use it right
       away, or is it (i) a whole lot harder and (ii) really, really slow,
       to do that.
	
	etc etc

I am using this forum 'cuz I am sure that others have gone through similar
experiences, and would have good advice to offer. I am NOT afraid of being
deluged by mail (PLEASE e-mail any replies directly). If anything
interesting turns up, I will post again. So, don't delay, write to me
today !

Sean Marrett

Use the following uucp address..not what the header says.
{..ihnp4,decvax etc}utcsri!mcgill-vision!silvest1
AND/OR
{..ihnp4,decvax etc}utcsri!mcgill-vision!vnode!webb1
OR
...!philabs!micomvax!musocs!mcgill-vision!etc
From the ARPANET:
(hopefully)
utcsri!mcgill-vision!silvest1@uw-beaver
OR
utcsri!mcgill-vision!vnode!webb1@uw-beaver
-- 
					der Mouse

{ihnp4,decvax,akgua,etc}!utcsri!mcgill-vision!mouse
philabs!micomvax!musocs!mcgill-vision!mouse

Hacker: One responsible for destroying /
Wizard: One responsible for recovering it afterward


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