Technology Library

Jun 1998
The Engineering of (Mixed Technology) Systems

Components of systems may be built using a single technology or several technologies, such as electronics, software and mechanics, but systems incorporate several technologies. A consequence is that systems encompass interfaces between components of the various constituent technologies and the real world. The more complex the system the more likely it is that the development process will be incremental and involve producing successive physical prototypes which iterate towards the desired functionality and performance of the target system. The modeling of complex systems requires radically different technologies and approaches if safe systems are to be realized. In general, systems are too complex to be modeled using a single modeling technique. But using several systems models usually results in inconsistent views of time, signals and states.

This paper addresses the efficacious modeling of predominantly digital systems, including the trans-technology interfaces, and discusses techniques which enable the consistent treatment of time, causality and signals. The relationship between modeling and engineering is direct. Systems should be specified using notations that admit accurate modeling which is consistent with the system functioning and performance after synthesis. Competent modeling naturally supports iterative system development via soft prototypes and, when sufficiently fast and accurate, obviates the need for all but a final physical prototype. For systems on a chip, or on a circuit board, the process is the same.