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A special purpose simulation engine based on the Time Warp mechanism is proposed to attack large-scale discrete event simulation problems. A key component of this engine is the rollback chip, a hardware component that efficiently implements state saving and rollback functions in Time Warp. The algorithms implemented by the rollback chip are described, aa well aa mechanisms that allow efficient implementation. Results of simulation studies are presented that show that the rollback chip can virtually eliminate the state saving overhead that plagues current software implementations of Time Warp.

A new Conservative algorithm for both parallel and sequential simulation of networks is described. The technique is motivated by the construction of a high performance simulator for ATM networks. It permits very fast execution of models of ATM systems, both sequentially and in parallel. A simple analysis of the performance of the system is made. Initial performance results from parallel and sequential implementations are presented and compared with comparable results from an optimistic TimeWarp based simulator. It is shown that the conservative simulator performs well when the "density" of messages in the simulated system is high, a condition which is likely to hold in many interesting ATM scenarios.