Portable code for complex critical systems

A common requirement on future safety-critical systems is to support hardware interchangeability. In this paper work sponsored by British Aerospace Military Aircraft and Aerostructures is reported which addresses this issue. Interchangeability is motivated by the need to perform technology upgrades within a system when components become obsolete-hardware computer components are often superseded within a few years, whereas the total system may have a lifetime of decades. Hardware interchangeability, implies that software needs to be moved to a new platform and execute with minimal network or disturbance to the rest of the system. Movement of software to a new (different) hardware platform is a difficult proposition without network, e.g. re-compilation of the software. For safety-critical systems, the rework could also include test, analysis, verification and validation efforts, adding to the overall cost of the change. In this paper the problem of movement of software to a new platform is considered, within the critical systems domain. The solution to the problem proposed in this paper is portable code (PC) whereby source code is compiled to an intermediate portable form that can then be instantiated to, or directly executed by any platform. This solution can remove much or all of the network costs involved in moving software to a new platform, thus substantially reducing system lifecycle costs.