On the correctness of the Sproull counterflow pipeline processor

The Sproull Counterflow Pipeline Processor Architecture has been posed as a common problem in asynchronous design, so as to compare various design methodologies with one another. Using DI-algebra we discuss a path to a decomposition of the problem, which is subsequently shown to be correct. In the process we discover several design decisions that may have an impact on the performance of such a pipeline. By also introducing two processes that act as the environment of the pipeline, we can restrict the pipeline correctness considerations to one pipeline element and the two environment processes.