systolic array
Beginner
A grid of tiny calculators that pass numbers to their neighbors, step by step. Each number gets used many times instead of being fetched again.
Novice
A grid of identical multiply-and-add cells. On every tick of the chip’s clock each cell passes its numbers to its neighbor, so a value read once from memory is used by a whole row or column of cells. It computes matrix products with few memory reads.
Expert
A regular mesh of processing elements in which operands move one neighbor per cycle. Which operand stays put (weights, outputs or inputs) defines its dataflow. It trades flexibility for operand reuse and short wires; utilization drops on small or oddly shaped matrices, and the cycles to fill and drain the array matter for small batches.
Explained in AI accelerators and datacenter (Industries).
See also: MAC (multiply-accumulate).