Introduction:

Parallel programs have considerably more complicated structures than do sequential programs. A parallel program has many threads to the computation, and each thread can have all the complexity of structure of a sequential program. In addition, there can be a complicated communication structure between these threads. Pictorial methods can help make the parallel structure more visible.

In this paper I describe a pictorial representation of occam programs. This representation has been developed as part of the Alvey ParSiFal project, for use by one of its tools, GRAIL.

The structure of the program is shown pictorially, by use of nested boxes, and by arrows. This pictorial representation continues down to the level of an individual statement. Statements themselves are shown textually - little is gained, and much is lost, trying to contrive a pictorial representation for these.

@inproceedings(SS-GTSE,
  author = "Susan Stepney",
  title = "Pictorial Representation of Parallel Programs",
  booktitle = "Graphical Tools for Software Engineering",
  editor = "Alistair Kilgour and Rae A. Earnshaw",
  series = "BCS conference proceedings",
  publisher = "CUP",
  year = 1989
)