Em View is an extensible visualization system that integrates to emstar-based systems, simulators, and emulators. It can also be connected via gateways and other means to other systems. Em View grew out of a need to develop a unified visualization system to replace a host of individually developed single-application visualizers. Thus, Em View is designed specifically to visualize a wide range of applications from a single reusable framework. A highly customizable interface enables multiple visualization schemes to coexist in a single display, while a simple API significantly reduces the coding required to develop new application specific visualization modules.