Processing element (PE)
Beginner
One of the small, identical calculator cells in a grid. Each one does a tiny piece of the work and hands numbers to its neighbors.
Novice
The repeated cell of a spatial or systolic array. In an AI accelerator it is usually one multiply-accumulate unit plus a few registers that hold a stored value and the values passing through.
Expert
A MAC datapath with operand and partial-sum registers, sometimes a small register file (0.5 kB per PE in Eyeriss) and local control. Its contents and its links to neighbors define the dataflow; its pipeline registers set the array’s clock rate.
Explained in Systolic arrays (Architectures).
See also: systolic array, MAC (multiply-accumulate).