Experiences assessing high integrity software

The author presents the methodology called RISCS (Reliability, Integrity and Safety Critical Studies) developed by CSE for assessing the safety and reliability of the computer-based control systems. The methodology permits differing hazards of the system to be assessed at differing levels, making use of the most powerful assessment techniques available. RISCS assesses the reliability, system integrity and safety in the context of the complete system and not just the software, though this is an important part of the assessment. What is more the client is able to decide on the level of assessment required. The RISCS approach consists of a number of consecutive stages: hazard criteria selection, legal/economic consideration, determination of assessment level, selection of assessment, and evaluation