Ptolemy Classic is a heterogeneous simulation and design environment supporting multiple models of computation. It is written in C++, and has a (now rather old) graphical user interface for constructing models visually as block diagrams. It supports dataflow, discrete-event, process networks, synchronous/reactive, and finite-state machine models of computation. It can generate implementations in C and assembly code for at least two programmable DSPs from certain dataflow descriptions of systems.
The Ptolemy project continues to use Ptolemy Classic occasionally as a laboratory for experimenting with models of computation, but most of our work has shifted to a new Java-based environment called Ptolemy II.