I have no doubt whatsoever about the ability to do that for scientific algorithms given enough time, so it is the accelerated schedule that is a source of high risk; people are not used to having to program that way. So, it is a good combination of the system's software, which tends to lag pretty badly in terms of its ability to exploit these very complicated processors, and then the applications.

The one thing I did not emphasize at all is that the way we have obtained this wonderful Moore's curve for the processor increase in speed is not so much by having faster clocks on our cycle speeds, but by making the guts of the processor much more complicated. And so, theoretically, if everything works you get this wonderful speed. But it means keeping several arithmetic units busy, loading and storing data simultaneously, and that is a hard thing to do. So, to actually get the benefits of these faster processors, even one processor, is beyond what many compilers can do.

Andrew White, Los Alamos National Laboratory: Thom mentioned the Science Simulation Plan and the PITAC response as a new program for FY2000. How would this new initiative and ASCI/Stockpile Stewardship play together?

Paul Messina: One of the things that I hope to do in part during my 2 years in ASCI is to work out a way that the two efforts can get mutual benefit. So, specific things that I can imagine are that perhaps the SSX SSStar program will select machines that are similar to the ones that ASCI has selected. Then, these two things that I just identified as the highest-risk items, the system software and tools and the algorithms, could be developed jointly so that we would be able to actually use the machines. I would say that is a real target of opportunity, to have very similar machines instead of deciding to diverge here and therefore have to develop all new and different algorithms.

So, at the level of helping to mature the system, I would first think of software, tools, and the algorithms for the applications. One could imagine sharing facilities. That is practical, but often politically unpalatable, so I do not know that there is much hope of doing that. But I think that in figuring out how to use these new systems, making them robust earlier and sharing the results, and maybe even having joint teams doing applications, would help both tremendously.

Thom Dunning: I think one of the real benefits of ASCI is that it has made computational scientists start to ask such questions as, What would we do if we had 100 times more power on the desktop or 10,000 times more power on the very high-end systems? These are very good questions to be thinking about because that is the direction that the computer industry is taking us, whether it succeeds on the accelerated time scale as outlined with ASCI or whether it comes on a little more slowly.



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