On-line testing of an off-the-shelf microprocessor board for safety-critical applications

The paper describes the strategy adopted to implement on-line test procedures for a commercial microprocessor board used in an automated light-metro control system. Special care has been devoted to chose the most effective test strategy for memory elements, processors, and caches, while guaranteeing a minimum impact on the normal behavior of the whole system. Implementation of the described techniques will significantly improve the system ability to safely react to possible faults. This will be quantitatively determined in the subsequent dependability evaluation phase.