For complex systems, especially embedded systems, it is highly desirable to organize run-time objects into manageable units such as tasks, components, and subsystems. A UML structure diagram can be used to capture the structure of a complex class (say, task) and the run-time information about the contained objects. UML component and (sub)system diagrams are simply large-scale structure diagrams. UML deployment diagrams are used to define the deployment of software artifacts in the execution environment. As a case study, we show how to model the physical components and subsystems of the AT91SAM9G45 evaluation board.