HARP-1: a special-purpose computer for N-body simulation with the Hermite integrator

The authors have designed and built HARP (Hermite AcceleratoR Pipeline)-1, a special-purpose computer for solving astronomical N-body problems with high accuracy using the Hermite integrator. The Hermite integrator uses analytically calculated time derivatives of the acceleration, in addition to the acceleration, to integrate orbits of particles. HARP-I has a 24-stage pipeline to perform the calculation of the acceleration and its time derivative, which is the most expensive part of the Hermite scheme. The pipeline calculates one gravitational interaction at every three clock cycles. Thus, the acceleration and its time derivative of a particle are calculated in 3N+24 clock cycles, where N is the number of particles. The peak speed of HARP-1 is 160 Mflops.<>