Massively Data-Parallel Computers

There is a small but growing base of special-purpose machines in two forms: multicomputers (e.g., hundreds and thousands of computers interconnected) and the SIMD (e.g., the Connection Machine, MasPar), some of which supply a peak of 10 times a CRAY Y-MP/8 with about the same peak-delivered power (1.5 GFLOPS) on selective, parallelized applications that can operate on very large data sets. This year a Connection Machine won the Bell Perfect Club Prize^[*] for having the highest peak performance for an application. These machines are not suitable for a general scientific workload. For programs rich in data parallelism, these machines can deliver the performance. But given the need for complete reprogramming to enable applications to exploit their massively parallel  architectures , they are not directly substitutable for current supercomputers. They are useful for the highly parallel programs for which the super is designed. With time, compilers should be able to better exploit these  architectures  that require explicitly locating data in particular memory modules and then passing messages among the modules when information needs to be shared.

The most exciting computer on the horizon is the one from Kendall Square Research (KSR), which is scalable to over 1000 processors as a large, shared-memory multiprocessor. The KSR machine functions equally well for both massive transaction processing and massively parallel computation.