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The GRAPE project

Figures gif and gif show the basic idea of GRAPE systems. The special-purpose device performs only the force calculation, while a general-purpose host computer takes care of everything else. In the special-purpose device, a pipeline which embodies the data flow for the force calculation calculates interactions at the rate of one interactions per cycle (around 30 operations/cycle). Multiple pipelines can be attached to one memory unit so that they calculate the force on different particles. With multiple memory unit, it is also possible for multiple pipelines to calculate partial forces on one particle.

Figure: The basic architecture of GRAPE

Figure: The force calculation pipeline

Table gif summarizes the history of GRAPE project. New machine has become larger and more complex, but at the same time more cost-effective, even when the improvement due to the advance in the device technology is discounted.

Table: History of GRAPE project

For N-body simulations of planetary formation and globular clusters, GRAPE approach proved itself to be extremely effective. In fact, significant fraction of N-body studies in these fields are now performed on GRAPEs, and many new and important results are published. Many copies of GRAPE hardwares are now used for SPH and N-body simulations in cosmology, galactic dynamics and galaxy formation.

Jun Makino
Fri Jun 5 15:55:17 JST 1998