In 1989, the United StatesAir Force (WI-,/A&W) awarded the Ada Embedded Computer Software Support (AECSS) applied research contract to SBS Engineering Incorporated. The objective of the AECSS effort is to enhance the support of A& software for advanced avionics systems. Specifically, the AECSS effort is designed to i&ntify and develop technology to support distributed multiprocessor Ada software. Since fault tolerance is an obvious requirement for safety-critical applications of thefuture, the AECSS research team has included a rudimentary but effective level of fault tolerance support.

TM paper describes in detail the implementation of “application-level” fault tolerance in rhe AECSS Distributed Ada testbed. Architectuml information describing the distributed system software is fmt briefly provided so that the fault tolemnce approach maybe filly appreciated. The current state of fault tolerance support is then dkcuss~ as well as potential approaches to supporting alternative fault tolerance capabilities.