Hybrid Hardware and Software Approach for More Reliable Computer Applications

Safety-critical aerospace applications have become increasingly dependent on a software component. However, conventional approaches to increasing the software reliability of these systems have focused on purely programming aspects. While these methods can all lead to techniques which should minimize the number of flaws in the logic of programs, none claim to result in generation of code with zero errors. Recognition of the fact that systems for improved code reuse, code testing, or automated code generation will remain imperfect, has inspired the present innovative proposal for a hybrid hardware and software approach for improving software reliability. The Phase I effort is therefore aimed at researching how to create a hardware "watchdog" which is pre-programmed with characteristics of normal execution and flow of the program. Any deviations from normal program execution would be sensed and corrected by the new hardware device. This research is encouraged by preliminary results with similar approaches for improving the fault tolerance of machine controllers. Success with this proposed effort will anticipate demand by NASA and the aerospace industry for improved reliability of critical systems. It will also lead to creation, in Phase II, of a product for the commercial market which provides both soft and hard fault tolerance in the software running on personal computers.