The composite signal flow model of computation targets systems with significant control and data processing parts. It builds on the data flow and synchronous data flow models and extends them to include three signal types: non-periodic signals, sampled signals, and vectorized sampled signals. Vectorized sampled signals are used to represent vectors and computations on vectors. Several conversion processes are introduced to facilitate synchronization and communication with these signals. We discuss the severe implications that these processes have on the causal behavior of the system.We illustrate the model and its usefulness with three applications. A co-modeling and co-simulation environment combining Matlab and SDL; a high level timing analysis as a consequence of the operations on vectors; conditions for a parallel, distributed simulation.