IBM vs VAX/unix
ron%b...@sri-unix.uucp
Oh well, time to start the big computer/little computer flames.
I agree with all of your first paragraph that anything that can
be put on one chip is cheap, etc. One of the big problems is that
industry has this "one chip" CPU brain-set. Companies can't seem
to succeed by releasing a "two chip" CPU even if it costs only
50% more but provides 300% of the capacity. This dates back even
to the 6800. Original plans called for an even nicer implementation
of this chip, but it had to be scaled back because it wouldn't fit
into one IC and marketing decided no one would buy a two chip CPU
regardless of how good it was.
You seem to limit yourself to the idea that only microprocessor CPU's
are cheap. *WRONG* The CPU these days is almost always the cheapest
part. You can get a 11/780 CPU (just the boards and backplane) for
about $50,000. However the minimal 780 system costs $140,000 (with
the console terminals as the only peripheral). The minimal practical
configuration is abou $270,000.
I totally disagree with your last paragraph. While a IBM PC is a wonderful
computer for home and I really like toting a Grid Compass on travel with me
but I wouldn't want to really have to work on one. A central computer has
some of the following advantages:
1. Since the cost is spread out over several users you can purchase
things like more expensive peripherals, large amounts of memory, etc...
that are used less frequently by any one user, but allows it to be
accessible when needed.
2. There is more CPU headroom for the reason specified in #1.
3. Someone else usually backs it up.
4. System support is shared by all the users. Which means one copy
of system software. (On our systems, this is put in RAM disk).
5. Communications between users on a single machine is almost always
easier than networking.
-Ron
rcon...@sri-unix.uucp
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
LCAMPBELL%d...@sri-unix.uucp
When you refer to "6,000 IBM PC's (running Un*x on 68000 boards)",
it's probably a bit more accurate to say "6,000 68000-based Un*x
systems with power supplies and keyboards by IBM"...
--------
Mats Wichmann
was just given a rather large grant from IBM, which will take the form
of a s**t load of PC's. Nobody quite knows what the disposition will be
yet; everything is still in the formative stages. *BUT*, the Physics Depart-
ment has been using the University's computing facilities the past few years
because they have never gotten the money to replace their old IBM 1620 (yes,
you read that right!!!); now it looks like they will never get their own
machine because people are starting to say "why should we buy a large
expensive machine, when we can get everybody a PC for their desk". The PC
clearly does NOT meet the needs of large number crunching applications that
physicists and astronomers, to name two groups, are likely to perform. But
becuase of the easy availability of the PC's, it looks like they may not be
able to get funding for a machine to do these sorts of things. The problem
here seems to be that the sort of hype surrounding the PC, and other
similar machines, is creating a blindness amongst the decision-makers
(who are typically NOT computer users to any great degree) to the total
needs to their computing environment. By all means, use a PC if it is
appropriate for your needs, but let's not completely ingnore the need
for larger computational machines as well.
Another perspective is my own. When I was a student, competition for
the computing facilities at UC was fierce (although not quite as bad as
it is today). All undergraduate classes were confined to a bunch of PDP
11-70's, only one of which belonged to the CS dept. outright. The purpose
was to provide a programming environment for testing out certain concepts
being taught in the classes. This environment could be provided by a micro
of the ilk of an IBM PC. Basically, what I needed for COURSE work was
the pascal interpreter/compiler, a c compiler, editor, and a couple
of other utilities (program beautifiers, printer spooler). Most of what
I learned about UNIX, and what made me employable as I came out of college,
was done on my own time, by browsing through the system and trying various
things out. Trying to put each student on an individual machine almost
eliminates this aspect - which is there for anyone who cares to use it
right now. With a small disk on the system, the amount of stuff that
can be stored permanently is quite limited. I had the opportunity to
browse through those portions of several huge disks which were not
protected - and managed to learn quite a bit from that. I would not
want to give this up. I don't really object to some of the load
being offloaded onto smaller machines, but not the entire curriculum.
And the lower-level the machine, the less the value to the student. Thinl
of it this way - most of you are involved with the UNIX system in some
way or another. If it were your decision to hire, say four years from
now when the current batch of undergrads have finished college, a
programmer who had done all of his course work on one machine only, what
would look more attractive:
1) Apple II
2) IBM PC Running MS/DOS
3) IBM PC running PC/UX
4) 68000-based machine with UNIX System V or BSD 4.2
5) VAX 11/780
MY contention is that the Apple is already obsolete, and the technology of
the PC is already very near to it. The 68000 or the VAX, on the other hand,
present lots of interesting features, that even if nobody is building those
particular machines any more, would seem to me to bode well to picking up
whatever the current technology is. Four years from now, probably all of
those machines will be near obsolete.
Okay, just my opinion, but certainly grounds for some thought, isn't it???
If it were my decision, the only way I would put students on something
like the PC would be if they were truly well networked together with
some bigger machines, such as Vaxen, so that the resources were there for
those who needed/wnated them.
Mats Wichmann
Dual Systems Corp.
...{ucbvax,amd70,ihnp4,cbosgd,decwrl,fortune}!dual!mats
It now became apparent (despite the lack of library paste)
that something had happened to the vicar; [ Edward Gorey ]
co...@udel-relay.arpa
Your comments about PC's vs. VAX/unix were interesting. I
happen to agree with what you said. Unfortunately, I'm afraid the
audience on this net understands the "use PC's for what they are
good for" philosophy. Like you said, it is those administrators
who don't really use computers that need to learn more.
This brings mind a similar situation. Everyone agrees that
a VAX 11/780 just isn't as powerful as say an IBM 3081. What DEC
seems to be doing is providing a very nicely integrated network
(VAXCluster) so they won't loose people (or as many) to other vendors.
A cluster permits people to transparently access files on a remote
machine, access them from a node who sole purpose is a file server (HSC50),
and access remote print and batch queues as if they were local (under VMS).
This clearly won't compete with mainframes running single jobs that require
huge resources, but it does permit dispersion of load with hassling the
user to do it.
Is there already something out there for micros that does
analogous things?
KC
co...@udel-relay.arpa
r...@brl-tgr.arpa
Actually VAXCluster is a poor excuse for not having a new machine
out in over six years. It's expensive too (albeit not as bad as
going IBM). If all you want is UNIX and aren't locked into UNIBUS
peripherals there are a whole handful of faster/cheaper minis on
the market with better support.
-Ron