Currently, we are facing a computer software crisis. The ever increasing burden of maintaining software in businesses with large software holdings has led to this crisis. Over $30 billion per year is being spent on software maintenance worldwide. One solution to the current software crisis is to produce software which has high maintainability. Highly maintainable software can be produced by effective software design; that is, the application of flexible, simple, visible, and easy to use design methodologies and tools. A new software design tool, the Pseudocode-Box (PB) diagram, is proposed in this study to meet these requirements. After presenting a critical evaluation of some currently available methodologies and tools, the PB diagram is proposed with detailed rationale, advantages and disadvantages, basic structure, and an example of actual usage. Next, three performance measures of PB diagrams: understandability, productivity, and adaptability are explained. Then a research methodology to evaluate the performance of PB diagrams is introduced; a quasi-experimental design is adopted. To insure internal and external validity, a separate-sample pretest-posttest control group design is used. Next, three hypotheses regarding understandability, productivity, and adaptability of the PB diagrams are tested. Experimental results provide clear evidence of the superior performance of the PB diagram during both systems development life cycle (SDLC) and systems maintenance life cycle (SMLC). The results support the hypotheses of this study. First, the PB diagram has better understandability than that of the Nassi-Shneiderman (N-S) chart. Secondly, the PB diagram results in higher productivity than that of the N-S chart. Thirdly, the PB diagram is more adaptable in terms of total time required during SMLC than that of the N-S chart. Finally, an ideal combination of software design methodologies and tools for use during both systems development life cycle and systems maintenance life cycle is discussed. Limitations of this study are addressed. And directions for future research are suggested
