From: jcbhrb@nic.cerf.net (Jacob Hirbawi)
Newsgroups: comp.sys.transputer
Subject: RE: IMPORTANT questions. please read.
Date: 22 Aug 92 01:23:26 GMT
Organization: CERFnet

With a subject line like this how can I not respond ;-) 

In comp.sys.transputer <zv_nwff.cliff@netcom.com>
Cliff Rodriquiez <cliff@netcom.com> writes:

> I am doing a VR game.  My original hardware choice
> was to use transputers for the graphics pipeline.

> If you have experience with transputers and graphics,
> could you please answer one or more of these questions?
> I'm funding this project myself, the more info I have
> the better chance of the investment being worth while.
> thanks in advance.....cliff

> note: i am looking at an intel 486 system and adding
>       cards on for co-processing.

Not a bad setup. I assume that you will be using the PC for the
non-computationally intensive tasks like user interface and the
Transputers (or i860's) for the real graphics work. You might
want to consider a seperate graphics card that is independant of
the PC's.

> 1. on a price per performance basis, is the i860 better
>    than the transputer?  i see the very low mips of 
>    a T800 and wonder how many i would need in parallel
>    to make up one i860.

I don't think the T800 has enough power for really complicated graphics
or image processing; unless you use lots and lots of T800's. The i860 
is more powerful but has none of the "parallelism" of Transputers. If
you can, wait for the T9000; otherwise you might want to consider a hybrid
situation: one or more i860's for processing connected to a Transputer
for the I/O. As a rough benchmark of processing power an i860 can do a 1K
complex FFT in something like 1 msec. I don't think a T800 can do much 
better than 40 msec.

> 2.  transputers seem to be a lot more expensive than
>     i originally thought.  if i want to put 3-4 on
>     my machine and give them each a couple of meg
>     i am talking about serious bucks (pricing from
>     my local inmos dist in sunnyvale ca).  has anyone
>     seen good pricing?  is there an alternative to
>     using inmos transputers?  what are some prices 
>     you have seen for: transputer boards for pc's,
>     trams, memory for trams.  
    
And I have a quote from Inmos of about (US) $700 for a T9000 !.
I don't think you can really do this type of work too cheaply.
To be fair though an i860 or even a 486 isn't that cheap either.
There are many other companies that sell TRAMS besides Inmos.
Ask Inmos for a Transputer Yellow Pages (I think that's what they 
call it!) for a list. Transatec usually has lower prices than Inmos
but there are smaller companies that might have lower prices still.

> 3.  i am currently developing my own 3d routines that
>    will be ported over to the transputer env.  the i860
>    has quite a lot of 3d hardware/software support.  has
>    anyone see graphics libraries and/or specialize graphics
>    hardware for the transputer?  my catalog only shows a 
>    simple (vga like) display chip.  i would like something
>    a little more performance oriented tward 2d and 3d 
>    graphics.

I will be developing a similar library for the Inmos IMS B419 soon.
For those unfamiliar with this, it has a T800 with 4MByte RAM, 2MBytes
of which are dual ported Video RAM. It also has a G300 Video controller
so it can, under software control, drive several types of RGB monitors.
This will be an all OCCAM code and will include contours and 3D surface
graphics with hidden surface removal. I will start as soon as I work out
all the bugs from a C++ version. I don't think I understand what you mean by 
the i860 having a lot of 3d hardware/software support. As far as I know it 
doesn't even have 2d support ( you still have to draw lines pixel by pixel 
under software control ).

> 4.  last question:
>
>    if i am going to all the trouble of making a graphics
>    pipeline with transputers that are around 1-2 mips,
>    am i kidding myself when compared to:
>    specialized 3d hardware designed for high performance
>    polygon throughput, coupled with a risc based motherboard
>    giving me 15 mips.  

If you use T800 then yes , you are kidding yourself :-) . But if you
use T9000 or i860/T800 combination then definitely not. The risc 
machines you are talking about are expensive and you still need to network
several of them to get any type of VR perfromance; and I haven't even
mentioned the price of the software for these machines. Now let's say a
T9000 costs $700 and 4MBytes of DRAM $100 and say $200 for other parts;
(let's forget about development and manufacturing costs for now).
You have 25 MFlops (or 200 Mips or anyway you look at it: a lot of
power) *with built-in parallelism* for about $1000. The real cost is higher,
but not by much. And you can stamp out as many copies as you need! . 
Now if you are a company and try to sell these things you have to cover 
advertising, payroll, insurance, and all that jazz and the price skyrockets.
But for your own use you have a reasonably priced processing unit.

Jacob Hirbawi
JcbHrb@CERF.net