When Japan's Earth Simulator surged to life two years agoas the world's most powerful supercomputer, it heightened concerns that computing efforts in the United States were falling behind (see "Supercomputing Resurrected," TR February 2003). The machine performs more than 35 trillion operations per second, or 35 teraflops, at its peak speed. Now, two contenders that will vastly outperform the Earth Simulator are waiting in the wings: a 360-teraflops IBM-built machine at California's Lawrence Livermore National Laboratory, scheduled for completion in 2005, and a 100-teraflops Cray system at Tennessee's Oak Ridge National Laboratory, due to be up and running in 2006, and possibly expanding to 250 teraflops the following year.

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