Applications considerations in the system design of highly concurrent multiprocessors

A five-year series of studies, which ended in 1982 and which was supported in part by NASA and in part by Burroughs Corporation, led to the system design of a very large, very high-speed multiprocessor. This system was intended to solve large scientific problems, especially modeling problems such as those in computational aerodynamics. The performance objective was to sustain execution rates up to one billion floating-point operations per second with problems requiring 40 million words of main memory. The viability of this design depended on an in-depth understanding of the projected applications of the system. An overview of the project objectives and the resulting 128 processor design will be presented showing the local private memories available to each processor, the 64 million word shared memory, the dual-omega interconnection network, and the important programming concepts. During the design of the system, studies were conducted which determined the number of processors (a tradeoff with individual processor speed), the memory organization (program and data, private and shared), and the structure of the networks used to interconnect the processor and memory resources. These studies and the important application-related considerations are presented. Although this system was never constructed and tested, it was extensively simulated and the design was completed to sufficient detail to develop a reasonably accurate parts list and implementation plan.