Software change control board

In one of the leading UK pharmaceutical companies, a printed circuit board assembly in a plant controller was replaced after a failure with an ostensibly identical unit. To everyone s complete surprise, this simple action, regarded as relatively routine, led to a major operational incident. The cause was found to be an EPROM chip on the replacement board. This chip not only carried an upgraded version of the software on the original but also possessed different operational parameters. Despite the fact that the replacement printed circuit assembly had been successfully tested (in accordance with quality procedures), it was the lack of effective configuration management that allowed the change in the software to elude detection, which led directly to the failure. 

Inside the IXV spacecraft, the On-Board Software (OBSW) plays an important role. The OBSW manages the IXV elements that are necessary to perform all mission modes, including Launch, Orbital, Re-Entry and Descent-Flight, The IXV needs the OBSW to control the vehicle, perform experiments, monitor data, and provide data storage and telemetry, A number of constraints affect the OBSW it is embedded software, with hard real-time, dependability and safety constraints it must operate autonomously over extended periods of time it faces important hardware limitations and it has to cope with a hostile environment (radiation, large temperature changes). 

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