Date of Award


Document Type


Degree Name

Doctor of Philosophy (PhD)


Computer Science

First Advisor

Doris L. Carver


The goal of this research is to provide a graphical system that supports the program understanding process by representing the program's control flow, the code and the identifiers local to a specific point within the program. By having more information local to the point of interest, the programmer can maintain continuity in developing program understanding. The programmer can see loops, procedure calls, and other structures with respect to their execution order and can view them in the environment or the context in which they will execute. The Peec system supplies a graphical representation of the program's control flow in which the control structures are represented as tiers. The tiers are arranged in a three-dimensional space representing the program's operational flow. The body of the procedure or function is nested within the reference tier so that the programmer views the routine local to its reference point. Also, a list of live identifiers is displayable for the current tier element. The advantage is that the routine's text and the identifier list are local to the area of study and the programmer does not have to look elsewhere for the program text and the identifier definition. The programmer can maintain a continuity in developing program understanding using information local to the point of interest. The Peec system consists of the Peec compiler which transforms a Pascal program into tier and identifier information, and the Peec environment for modeling the program's operational flow image. The Peec environment provides the programmer many interactive capabilities. These capabilities consist of browsing the flow model, displaying text, displaying identifiers and transforming the three-dimensional flow model into appropriate views. These features are aimed at assisting the programmer in the processing of developing program understanding.