The Design and Implementation of an Asynchronous Microprocessor

Nigel C. Paver

Abstract

A fully asynchronous implementation of the ARM microprocessor has been developed in order to demonstrate the feasibility of building complex systems using asynchronous design techniques. The design is based upon Sutherland's Micropipelines and allows considerable internal asynchronous concurrency. The design exhibits several novel features including: a register bank design which maintains coherent register operation while allowing concurrent read and write access with arbitrary timing and dependencies, an ALU whose speed of operation depends upon the data presented, and an instruction prefetch unit which has a non-deterministic (but bounded) prefetch depth beyond a branch. The design also includes many complex features commonly found in modern RISC processors, such as support for exact exceptions, backwards instruction set compatibility and pipelined operation.

This thesis introduces the Micropipeline approach and discusses the design, organization, implementation and performance of the asynchronous ARM microprocessor which was constructed in the course of the work.

The thesis is available in postscript form by ftp (1.4MB compressed) and the colour postscript pages are available here (as a 900K compressed tarfile of the colour postscript pages)
Some comments about the postscript (produced by FrameMaker) are included here (ghostview users should read this)