Resumen
The growing tendency to embed software in powerful and invasive physical devices brings greater risk, especially in medicine, where software can save lives but also kill. Software problems led to the recall of 200,000 implanted pacemakers and defibrillators between 1990 and 2000. In the 20 years prior to 2005, the US Food and Drug Administration recorded 30,000 deaths and 600,000 injuries from medical-device failures. How many of these incidents can be attributed to software is unclear, though separate studies have found that about 8% of medical-device recalls are software-related. This article argues that developers should produce direct evidence of their software's dependability. The potential advantages of this approach are greater credibility (as the claim is not contingent on the effectiveness of the practices) and reduced cost (because development resources can be focused where they have the most impact). The direct approach, by definition, is straightforward. The desired dependability goal is explicitly articulated as a collection of claims that the system has some critical properties.