"Robert J. Bradbury" wrote:
> If they are taking an example out of the GRAPE book, they are designing the
> instructions for molecular modeling.
Perhaps, but....
I read the IBM announcement on their web site, and a New York Times article that
had a little more detail (can't vouch for its accuracy:
http://www.nytimes.com/library/tech/99/12/biztech/articles/06blue.html)
Neither piece had enough detail to really say what IBM's design plans are, but
among the few facts I gleaned from there were:
The "instruction
set" -- the total vocabulary of machine-language
instructions a computer understands -- will number 57
for Blue Gene, compared with about 200 for most RISC
machines. (NYT)
57 instructions is not a lot for a processor - Intel 486 has around 170, the IBM
390 (extreme CISC) has over 400. Of course these are general purpose processors,
and a special-purpose architecture like GRAPE probably has many fewer
instructions; however, I would expect many of those instructions to be relatively
complex to render in the hardware:
(From IBM's announcement):
"We call this new approach to computer
architecture SMASH, which stands for Simple,
Many and Self-Healing."
The SMASH architecture differs from existing
approaches in three ways:
It dramatically simplifies the number of
instructions carried out by each processor,
allowing them to work faster and with
significantly lower power and chip surface
requirements (the traditional approach is
to add complex features to gain
performance);
It will facilitate a massively parallel
system capable of more than 8 million
simultaneous threads of computation
(compared to the maximum of 5000
threads today);
It will make the computer self-stabilizing
and self-healing -- automatically able to
overcome failures of individual
processors and computing threads.
To me, this implies that their approach to the hardware design is unit simplicity for raw speed, massive redundancy for fault tolerance and throughput. It seems to me they intend to handle the complexity at a higher level (in the software).
> They may have sat back after
> doing the molecular modeling stuff and said, ok, now how can
> we turn the machine into a good data-mining computer, or a
> good speech recognition processor, or a good image processor
> and added some more instructions to round things out.
>
>
But even if I'm right, the task of designing software to make full use of the machine's capabilities may be so daunting that no one else will want to take it on, effectively making it a single-purpose machine. And this is likely the only one they will build, like Deep Blue.
Must sleep........