Systems for computer-aided development of software or hardware: A basis for comparative assessment.

Three mutually complementary main-stream approaches to the development of software or hardware for control-intensive applications such as communication protocols are identified and assessed: 1) Development through structured design. 2) Development through modelling. 3) Development through testing. The first is found to be an attractive and important component of most contemporary software or hardware development tools. The second is found to be the one which has sustained the most intensive theoretical investigation, but by itself of only limited value for software or hardware development, because of the general inability to translate directly from a model to an implementation. Informal models are found to be generally inadequate. The third approach is found to be potentially the most powerful, when interpreted as symbolic testing of an implementation. However, to be effective, it must be able to cope with the apparent intractability of such testing.