The Vortex: A Superscalar Asynchronous Processor

Abstract

The "Vortex" processor is a general purpose CPU with a novel architecture and instruction set. The primary feature of the Vortex architecture is many parallel function units which communicate through a central crossbar, instead of a traditional register file. Instructions are fetched in parallel by cache lines, as in a VLIW processor, but any data or structural dependencies are resolved deterministically by the hardware, as in a superscalar processor. The prototype Vortex CPU supports a 32-bit integer datapath and executes up to 9 instructions per cycle. It uses the "integrated pipelining" asynchronous design style, was fabricated in 2001 in TSMC's 0.15 mum G process, and runs at a typical frequency of 475MHz. Although the Vortex CPU itself has not been commercialized, many of its component circuits have been used in the products of Fulcrum Microsystems.