This paper deals with integrating an interactive simulator within a behavioral synthesis tool, thereby allowing concurrent synthesis and simulation. The resulting environment provides a cycle based simulation of a behavioral module under synthesis. The simulator and the behavioral synthesis are based on a single model that allows to link the behavioral description and the architecture produced by synthesis. The basic simulation-synthesis model is extended in order to allow for concurrent architectural simulation of several modules under synthesis. This paper also discusses an implementation of this concept resulting in a simulator, called AMIS. This tool assists the designer for understanding the results of behavioral synthesis and for architecture exploration. It may also be used to debug the behavioral specification.