Issue No. 12 - December (1968 vol. 17)
G.G. Langdon , IEEE
Abstract?Asynchronous circuits are analyzed from the stand- point of different constraints which may apply to the stray delays (zero-line delays, bounded delays, and the use of delay elements). The relationship between "hazard-free" sequential networks and "speed independent" circuits is illuminated. Speed independence is defined relative to a fundamental mode circuit (which in turn may be described by a flow table); the analysis is carried out from this stand- point. The allowed sequence graph may be used to detect critical races. A circuit is seen to be speed independent if and only if its circuit-derived excitation matrix has no 1-input change critical races. The generalization of the essential hazard has been studied in detail and is shown to be an obstacle to hazard-free realizations when line delays can be arbitrarily large.
Index Terms?Asynchronous circuits, fundamental mode, hazards, races, speed independence, stray delays.
G. Langdon, "Analysis of Asynchronous Circuits Under Different Delay Assumptions," in IEEE Transactions on Computers, vol. 17, no. , pp. 1131-1143, 1968.