ABSTRACT
Computer-based systems, generically referred to as Programmable Electronic Systems (PESs), are increasingly being used in safety-related applications. This trend is certain to continue because of the potential advantages such systems offer. The potential safety advantages will, however, only be realised if appropriate design and assessment methodologies are used. Unfortunately, many of the features of PESs do not enable the safety integrity to be predicted with the same degree of confidence that has traditionally been available for less complex hardware-based systems.
