HIGHLY PARALLEL COMPUTER ARCHITECTURE EMPLOYING CROSSBAR SWITCH WITH SELECTABLE PIPELINE DELAY

A crossbar switch which connects N (N=2.sup.k ; k=0, 1, 2, 3) coarse grain processing elements (rated at 20 million floating point operations per second) to a plurality of memories provides for a parallel processing system free of memory conflicts over a wide range of arithmetic computations (i.e. scalar, vector and matrix). The configuration of the crossbar switch, i.e., the connection between each processing element unit and each parallel memory module, may be changed dynamically on a cycle-by-cycle basis in accordance with the requirements of the algorithm under execution. Although there are certain crossbar usage rules which must be obeyed, the data is mapped over parallel memory such that the processing element units can access and operate on input streams of data in a highly parallel fashion with an effective memory transfer rate and computational throughput power comparable in performance to present-day supercomputers. The crossbar switch is comprised of two basic sections; a multiplexer and a control section. The multiplexer provides the actual switching of signal paths, i.e. connects each processing element unit to a particular parallel memory on each clock cycle (100 nsec). The control section determines which connections are made on each clock cycle in accordance with the algorithm under execution. Selectable pipelined delay in the control section provides for optimal data transfer efficiency between the processors and memory modules over a wide range of array processing algorithms. The crossbar switch also provides for graceful system degradation in computational throughput power without the need to download a new program.