A SPECIAL-PURPOSE COMPUTER FOR N-BODY SIMULATIONS - GRAPE-2A

We have developed GRAPE-2A, which is a back-end processor used to accelerate simulations of gravitational N-body systems, such as stellar clusters, a proto planetary system, and the structure formation of the universe. GRAPE-2A calculates the forces exerted on one particle from all other particles. The host computer, which is connected to GRAPE-2A through a VME bus, performs other calculations, such as time integration. In the simulation of gravitational N-body systems, almost all of the computing time is consumed in calculating the forces between particles. GRAPE-2A performs this force calculation with a speed that is much faster than that of a general-purpose computer. GRAPE-2A can be used for cosmological N-body simulations with periodic boundary conditions using the Ewald method, and for molecular-dynamics simulations of proteins and crystals. The computational speed of GRAPE-2A is 180 Mflops.