Perspectives on supercomputing: three decades of change

I am fortunate to have had access to supercomputers for the last 28 years. Over this time I have used them to simulate time-dependent fluid flows in the compressible regime. Strong shocks and unstable multifluid boundaries, along with the phenomenon of fluid turbulence, have provided the simulation complexity that demands supercomputer power. The supercomputers I have used-the CDC 6600, 7600, and Star-100, the Cray-1, Cray-XMP, Cray-2, and Cray C-90, the Connection Machines CM-2 and CM-5, the Cray T3D, and the Silicon Graphics Challenge Array and Power Challenge Array-span three revolutions in supercomputer design: the introduction of vector supercomputing, parallel supercomputing on multiple CPUs, and supercomputing on hierarchically organized clusters of microprocessors with cache memories. The last revolution is still in progress, so its outcome is somewhat uncertain. I view these design revolutions through the prism of my specialty and through applications of the supercomputers I have used. Also, because these supercomputer design changes have driven equally important changes in numerical algorithms and the programs that implement them, I describe the three revolutions from this perspective