2542	 A Software Design and Evaluation System	 A critical failure of current software system design and implementation methodology is that the performance of a proposed design is not evaluated before it is actually implemented. In this paper the reasons for this failure are explored and a new methodology which overcomes many of the difficulties is proposed. A system which integrates performance evaluation with design and implementation is described. This system is based on a simple high level language which is used to describe the evolving system at all stages of its development. The source language description is used as direct input to performance analysis and simulation routines. Using the performance information obtained from these routines as feedback the problems which adversely affect performance are detected early enough so that they can be corrected without costly major reimplementation of the proposed system. operating system development language processing software evaluation compilers system programming supervisory systems debugging program maintenance modeling system integration simulation
