Graphical programming of time-deterministic real-time systems

In this paper we present the Picasso programming language and the underlying design philosophy. Our goal is to provide programmers working with distributed embedded real-time systems with a tool to manage the complexity of this class of systems. The proposed tool allows easy and safe changes of the system software and hardware at any time during the lifetime of the system. This means that even during operation the system can be changed safely. This is not only important for enhancing the design process but is also necessary for a class of systems that need to be in service at all times. We have chosen to call this approach Change-Orientation. The most characteristic properties of the language are that it is graphical and that it shows time explicitly. All processing is described as functional transformations. These transformations are called processes. A very direct way of implementing a process is possible because the semantics of the description maps directly on the computation model of the processor