GRAPE-5: A Special-Purpose Computer for N-Body Simulations

We have developed a special-purpose computer for gravitational many-bodysimulations, GRAPE-5. GRAPE-5 is the successor of GRAPE-3. Both consist ofeight custom pipeline chips (G5 chip and GRAPE chip). The difference betweenGRAPE-5 and GRAPE-3 are: (1) The G5 chip contains two pipelines operating at 80MHz, while the GRAPE chip had one at 20 MHz. Thus, the calculation speed of theG5 chip and that of GRAPE-5 board are 8 times faster than that of GRAPE chipand GRAPE-3 board. (2) The GRAPE-5 board adopted PCI bus as the interface tothe host computer instead of VME of GRAPE-3, resulting in the communicationspeed one order of magnitude faster. (3) In addition to the pure 1/r potential,the G5 chip can calculate forces with arbitrary cutoff functions, so that itcan be applied to Ewald or P^3M methods. (4) The pairwise force calculated onGRAPE-5 is about 10 times more accurate than that on GRAPE-3. On one GRAPE-5board, one timestep of 128k-body simulation with direct summation algorithmtakes 14 seconds. With Barnes-Hut tree algorithm (theta = 0.75), one timestepof 10^6-body simulation can be done in 16 seconds.Comment: 19 pages, 24 Postscript figures, 3 tables, Latex, submitted to Publications of the Astronomical Society of Japa