Distributed simulation employing the Time Warp mechanism suffers from the enormous amount of memory it uses for state saving. The main goal of this paper is to address this problem b y introducing an incremental state saving technique with an optimized rollback mechanism. This method is especially suitable for simulations with large simulation states and a small amount of state change from one simulation step to the next. A very common example of such a simulation environment is digital logic simulation with up to a few hundred thousand signal and element states with only a small number of signals changing between two simulation steps.The event queue-indispensable p a r t of every discrete event simulation system-is used as a management tool for incremental state saving, thus reducing administration overhead drastically. A n optimized rollback mechanism ensures that only those parts of the simulation state are restored which have to be updated to the rollback time.Results on the experimental observation of memory usage for incremental state saving and time performance show the effectiveness of the introduced mechanisms on our Time Warp system.

In this paper an XML based language format to describe specifications of analog IPs and its usage in a validation flow is presented. With the help of an XMLSchema-Definition (XSD) a specification description language called Analog Specification Description in XML (ASDeX) is introduced. An ASDeX-file contains not only specification parameters but also measurement definitions and testbenches to enable specification validation based on simulation. The intention is to generate executable modules (tasks) for running simulations and extracting and checking the actual property values of analog circuits. The task generation is based on a generic template approach using a Meta-Simulator to achieve vendor independent analog IP representation including IP verification.

Time Warp has evolved to a common technique for distributed simulation. Speedup in Time Warp simulation systems mainly depends on two overhead factors: first, the load on the simulators has to be well balanced and second, communication and rollbacks have to be kept to a minimum.

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