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From: rconn%brl@sri-unix.UUCP
Newsgroups: net.micro
Subject: Re:  IBM vs VAX/unix
Message-ID: <17659@sri-arpa.UUCP>
Date: Sun, 18-Mar-84 07:08:54 EST
Article-I.D.: sri-arpa.17659
Posted: Sun Mar 18 07:08:54 1984
Date-Received: Tue, 20-Mar-84 01:13:29 EST
Lines: 62

From:      Rick Conn 

	I'm not sure what a mere dozen IBM-PC's or twenty Mac's will do
for you, but how about 6,000 IBM-PC's?  I think word of this will start
getting around quickly, and my information is only sketchy (but reliable).
MIT, with $Million support from both IBM and DEC, is setting up a rather
massive net of IBM-PC's and MicroVAXen (the numbers I heard were 6,000 PC's
and 160+ MicroVAX).  All of the PCs will be running a varient of UNIX from
a 68000 card, and the MicroVAX will act as local area network controllers
to provide communication with the larger mainframes et al.  The PC's will
be scattered about the campus, in dorms, classrooms, labs, etc.

	This was just an interesting tidbit.  You certainly have a point,
however, about your applications.  I agree that there are a large number
of applications which don't fit the PC world.  I've seen a CYBER 175
become bogged down under heavy LISP applications, and I've also seen
a VAX 11/780 die (in terms of response time) when just two or three users
are running certain compilations.  In these circumstances, in which
response time and performance from a human-interface point of view
degrade so fantastically, the application of PCs (IBM or otherwise) in
conjunction with the mainframes makes a lot of sense.  From the point of
view of the human, most spend the majority of the time in an editor or
similar tool.  The PC can be used to offload this type of processing quite
easily, and the user realizes fantastic response as a matter of routine.
When the user has finished his edit and then needs the compilation to be
performed, linking with the mainframe, transferring the file, starting
the compilation (perhaps as a batch job to start at 1 or 2 AM), and
then returning to the PC and continuing on with other work is a reasonable
scenario.  Additionally, while the PC can't be expected to do the compilation
or application by itself, it may act as a preprocessor, performing a
preliminary syntax check and looking at minor details before shipping
the file off for the main processing.  This can save a lot of time and
effort.

	A real-life example of this concept which has been around for some
time is PLATO.  Under the old PLATO IV, the CDC 6000 mainframe did all
the processing.  The terminals had some intelligence in them in that they
could receive a "DRAW CIRCLE at x,y with RADIUS r" command from the system
and do the graphics themselves.  Many high-order functions like this were
supported in the terminal itself, and PLATO IV claimed it could support
1,000 interactive terminals from the one mainframe.  Now we have PLATO V,
where the terminals contain micros.  Local editing of lessions, compilations,
execution, and other functions can be performed in the terminal without
accessing the mainframe.  The mainframe serves mainly as a data repository.
I have heard claims that PLATO V can support 10,000 terminals from the
ONE mainframe!  Most impressive.

	So, I feel that you certainly have a good point in emphasizing
that there are applications which micros can't meet at this time.  Leave those
to the mainframe.  But there is also the point that there are many
applications which micros CAN meet, and, combined in a distributed
sense with a mainframe, the flexibility, responsiveness, and utility
of the pair can help you to realize a much better working environment.
Software is the key to all of this, and in many cases, you would have to
write it yourself to meet your applications.  Precompilers on the micros,
communications software, and other utilities which support the distributed
environment are necessary before you can begin to make effective use
of the system for your original application.  MIT, as I understand it,
plans to write most, if not all, of their support software in-house.
The Univ of Illinois did indeed write PLATO and microPLATO themselves also.

		Rick