Abstract

Abstract. In this paper we present a method for modeling asynchronous digital circuits by timed automata. The constructed timed automata serve as\mechanical " and veri able objects for asynchronous sequential machines in the same sense that (untimed) automata do for synchronous machines. These results, combined with recent results concerning the analysis and synthesis of timed automata provide for the systematic treatment of a large class of problems that could be treated by conventional simulation methods only in an ad-hoc fashion. The problems that can be solved due to the results presented in this paper include: the reachability analysis of a circuit with uncertainties in gate delays and input arrival times, inferring the necessary timing constraints on input signals that guaranteeaproper functioning of a circuit and calculating the delay characteristics of the components required inorder to meet some given behavioral speci cations. Notwithstanding the existence of negative theoretical results concerning the worst-case complexity of timed automata analysis algorithms, initial experimentation with the Kronos tool for timing analysis suggest that timed automata derived from circuits might not be so hard to analyze in practice. 1

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