Application of boundary scan in a fault tolerant computer system

With the successful implementation of boundary scan as a tool for board test, there is a natural evolution towards using this powerful technique for system level test. Testing of back panel assemblies has traditionally been left to operating system or deterministic diagnostic tests. The fault detection capabilities of these tests is usually adequate, but an opportunity for improvement exists in the isolation of faults to a specific pin or device. Use of “board to board” boundary scan addresses this problem as well as several others. This paper describes the implementation of boundary scan in a Stratus Computer system both at the board and system level and discusses general hardware and software requirements. It outlines the cost savings of converting from the traditional approach