Asynchronous systems are being viewed as an increasingly viable alternative to purely synchronous systems. This paper gives an overview of the current state of the art in practical asynchronous circuit and system design in four areas: controllers, datapaths, processors, and the design of asynchronous/synchronous interfaces. 1 Asynchronous Control Classical asynchronous controllers were typically implemented as Huffman machines [67]. These machines do not use clocked latches or flip-flops: the state is simply stored on feedback loops. Typically a fundamental mode assumption is required, to insure correct operation: once an input change occurs, no new inputs may arrive until the machine has stabilized. Much of the basic theory on asynchronous state machines was developed by Huffman, Unger, and McCluskey (see [67]). Hazards, or the potential for glitches, are an important consideration in any asynchronous design [67]. In synchronous systems, the global clock usually filters out the effec...
Erik Brunvand, Steven M. Nowick, Kenneth Y. Yun