Subject: Re: Transputers...

From: Dave Stampe-Psy+Eng <[email-masked]>
Date: Tue, 22 Oct 91 22:53:13 -0400

> From [email-masked] Tue Oct 22 21:09:29 1991
> From: [email-masked] (Dave Newton)
> Subject: Transputers...
> To: [email-masked]
> 
> Howdy...
> 
> I'm trying to figure out why nobody on here has proposed using those $400
> T400 transputer cards hooked into a slave-PC to use for rendering...
> 
> My idea was basically have a T400 card w/ 1Meg ($396) and perhaps a few
> slave cards ($296?).  Each transputer has 10Mips sustained, 20 Mips
> peak.  The C compiler will automagically take advantage of other processors
> if the code is set up in a parallel fashion.  
> 
> Now, color me stupid, but wouldn't this be a cheap way to get a whole bunch
> of power?  The transputers could either be used in the main PC or put out
> in a slave PC somewhere.  I was planning on getting two dirt-cheap PC boards,
> three transputer boards (one for the main CPU, one for each slave) and
> communicate to the slave T400 boards using the on-board 20M data link...
> Let the slave boards handle the image calculation and spit it out via
> J. Random NTSC-board.
> 

Yep.. that would give you power.  But what has to be considered is cost
for the power, and software development.  I wouldn't take on the task
myself, because I have little experience in programming the Transputer systems.
You'd have to do at least the rendering stuff in assembly, too.  Have
you got cost quotes on the video cards?  Do they double buffer?  

Eventually we'll have to get renderers on all sorts of platforms.  The
Amiga, Atari, IBM PC etc. are being considered first because they're
the most common.   The Amiga-IBM idea was suggested because of the
dedicated hardware in the Amiga for graphics.  If you can get some
estimates on how fast the Transputer can do graphics, it might be
worth discussing it.

Possible problems:  If the 20M(bit) transputer link is used to talk to the
video buffer, how much overhead is there (i.e. do you have to send both 
address ans data, or is there a burst mode)?  How many units can talk to
the video board at once? etc. etc.  I used to have access to the data
on this stuff, but not currently.  Hope you can fill me in again.

- Dave Stampe

---

From: [email-masked]
Date: Wed, 23 Oct 91 10:22:20 -0600

I have also considered transputers for high speed rendering.  I was
interested in complex scenes with thousands of polygons rather than
stereo, but they should work for either.  My idea was one transputer
with lots of ram to store the display list and n transputers suitably
connected to video ram to do the rendering.  Then the PC would be used
to control the whole system and to talk to the user.  After seeing the
specs on the new T9000 (Byte, August 1991) I realized that these would
make a very powerful system.  However, at this point in time I don't
have the money to buy a bunch of transputers.  (Just an aside, there
really isn't an assembly language for the transputer.  If the C
compiler doesn't generate fast enough code for you then you would
write in OCCAM.  However, from what I have heard of the quality of the
C compiler, you are unlikely to need to do this.)

However, I haven't given up on the transputer.  If you have addresses
for companies which are selling PC transputer cards I would love it if
you sent them to me.

I really think that people who are interested in VR are going to have
to look at some kind of parallel architecture.  It is very unlikely
that you will be able to get a single serial CPU that is fast enough.
Also, VR is quite amenable to parallelizing.  A cpu for input devices,
a cpu (or more) for stereo output, a cpu for sound, a cpu for the
motion platform, a big cpu to coordinate things, and a collection of
cpu's to model objects.  The only question is whether 100Mbps
interconnect is fast enough.  Anybody know of a transputer board that
has NTSC output and another with a/d and parallel inputs?

Dudley Irish
________________________________________________________________________
Dudley Irish / [email-masked] / Manager Computer Operations
Center for Scientific Computing, Dept of Mathematics, University of Utah

The views expressed in this message do not reflect the views of the
Dept of Mathematics, the University of Utah, or the State of Utah.

---

From: James Helman <[email-masked]>
Date: Wed, 23 Oct 91 10:28:31 -0700

A cpu for input devices, a cpu (or more) for stereo output, a cpu
    for sound, a cpu for the motion platform, a big cpu to coordinate
    things, and a collection of cpu's to model objects.

This is very close to what Division Ltd. system does.  Their ProVision
system even uses transputers (Iann Barron from Inmos is Division's
chairman) with a couple i860's thrown in for FP speed.  MP systems can
provide better price/performance.  The big question is whether the
general purpose MP's (off the shelf PCs, Suns or SGIs) will get cheap
enough, fast enough.  If not, special purpose systems whether home
brewed or off-the-shelf like PROVision look attractive.

-jim

Jim Helman					Lab:  (415) 723-9127
Stanford University				FAX:  (415) 591-8165
([email-masked]) 			Home: (415) 593-1233

"The power of the computer is locked behind a door with no knob."
							-B. Laurel

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From: [email-masked] (Dave Newton)
Date: Wed, 23 Oct 91 12:22:17 CDT

In a previous message, [email-masked] said:
> (Just an aside, there really isn't an assembly language for the transputer.

   That strikes me as odd, since the $396 T400 board I mentioned comes with
C, Occam, and assembly.

> The only question is whether 100Mbps interconnect is fast enough.

   Um, I would certainly hope so.  That two-page article about the VPL thing
was using straight ethernet for their interconnects.  If 100M isn't fast
enough, there's a serious software problem, I'd have to say.

---

From: J Eric Townsend <jet>
Date: Wed, 23 Oct 91 13:00:54 CDT

>enough, there's a serious software problem, I'd have to say.

Ether isn't fast enough for parallel computing.. Intel found this out
with the iPSC/1.  The iPSC/2 and iPSC/860 use proprietary "Direct Connect"
technology that runs dedicated bit-stream lines w/ almost no protocol from
one node to the next.

-- 
J. Eric Townsend - [email-masked] - Systems Wrangler, UH Dept of Mathematics
vox: (713) 749-2126  '91 CB750, DoD# 0378, TMRA# 27834
PowerGlove mailing list: [email-masked]
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