Systolic Super Summation

  • Authors:
  • Peter R. Cappello;Willard L. Miranker

  • Affiliations:
  • Princeton University, Princeton, NJ;New York University, New York, NY

  • Venue:
  • IEEE Transactions on Computers
  • Year:
  • 1988

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Abstract

A principal limitation in accuracy for scientific computation performed with floating-point arithmetic is due to the computation of repeated sums, such as those that arise in inner products. A systolic super summer of cellular design is proposed for the high-throughput performance of repeated sums of floating-point numbers. The apparatus receives pipelined inputs of streams of summands from one or many sources. The floating-point summands are converted into a fixed-point form by a sieve-like pipelined cellular packet-switching device with signal combining. The emerging fixed-point numbers are then summed in a corresponding network of extremely long accumulators (i.e., super accumulators). At the cell level, the design uses a synchronous model of VLSI. The amount of time the apparatus needs to compute an entire sum depends on the values of summands; at this architectural level, the design is asynchronous. The throughput per unit area of hardware approaches that of a tree network, but without the long wire and signal propagation delay that are intrinsic to tree networks.