Safety computer systems special applications

SwS is a special aspect, and subset, of system safety it is also sometimes referred to as SwSS. The scope and coverage of SwS includes computer software, firmware, and programmable logic arrays. SwS is primarily concerned with application software developed as part of a system development program. However, due to the permeating nature of software, SwS must also consider operating systems, compilers, software tools, and reused software, including any form of COTS software that is utilized in the system. In the case of SwS, actual hazard risk cannot be calculated thus, acceptable risk is nebulous and is based on a diverse SwS process. 

The redundant computer DIGISAFE XME is based on a redundancy management protocol that allows two coded uniprocessor computers to work as symmetrically as possible. Each computer (called units) is intrinsically safe, and the maintenance of consistency between the execution contexts of the two units allows the switching or transition to the non-redundant (isolated) unit at any time, without requiring special precautions at the application or system level. This last point is extremely important because it significantly reduces system complexity and the associated safety analysis. 

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