Application-specific Processor Architecture: Then and Now

We first relate the architecture of systolic arrays to the technological and economic design forces acting on architects of special-purpose systems some 20 years ago. We then observe that those same design forces now are bearing down on the architects of contemporary general-purpose processors, who consequently are producing general-purpose processors whose architectural features are increasingly similar to those of systolic arrays. We then describe some economic and technological forces that are changing the landscape of architectural research. At base, they are the increasing complexity of technology and applications, the fragmenting of the general-purpose processor market, and the judicious use hardware configurability. We describe a 2D architectural taxonomy, identifying what, we believe, to be a Bsweet spot^ for architectural research.