Asynchronous Controller Design

This paper introduces a new method for the synthesis of gate-level asynchronous controllers. The method is based on a user-level specification formalism, the path model, and a simple algebraic tool, the signal calculus, that in combination provide a formalism for the specification and analysis of path-model designs. The path model view of communication is state-based as in other asynchronous finite-state-machine methods; however it focuses on the critical component of state machines, the paths, and ignores other non-critical free states. The signal calculus, a temporal lifting of Boolean logic, helps to formalise path-model specifications algebraically, removing much of the inadequacy of traditional tabular tools like flow tables, with their dependency on table cells that is exponential in input size. The method is demonstrated on two examples. Li Xiaolei is a DPhil student in the Programming Research Group at the University of Oxford. Jeff Sanders is Senior Research Fellow at UNU-IIST, having recently joined from the Programming Research Group at Oxford. His interests lie largely in Formal Methods. Copyright c © 2007 by UNU-IIST