Design validation of digital systems

The design process of a digital system involves conversion from the mission objectives expressed in natural language to a specification which is hopefully complete, consistent, and correct. However, there is extensive literature describing system failures that shows that this conversion process is error-prone. In addition, it is also found that correcting the design errors would be very expensive, if the errors are not found earlier. As a result, how to spot, reduce, or even eliminate these errors, becomes an important problem in developing a digital system.In the specification refining and validating process for a digital system, using an informal method is necessary, because the process needs engineering estimation about the characteristics of operational environment, engineering judgements about the system characteristics wanted, and tradeoffs among conflicting system attributes. The validation of the specification definition can't be fully automated and must rely on system designers' manual intervention. A checklist of design criteria or guidelines will help them in this process.In order to have a better insight into what can go wrong in system design, a simple model for system development is presented. For the purpose of later analysis, a system and environmental model using parameters is defined to show what are the important parameters concerned in the interaction of a system and its environment. In order to identify what are the most problematic areas in specification defining process, a taxonomy of the past system failure cases according to available information is presented.For validating the timing relationship of a round-robin systems, a set of timing constraints is developed. For efficient buffer size allocation, a set of criteria for system loading and buffer allocation is derived. For validating a system specification in a comprehensive manner, an expanded set of design guidelines or criteria is produced, which is much more comprehensive than those previously published.