Multi-processor systems are becoming more prevalent due to the many advantages which they offer over single-processor systems. A multi-microprocessor system can smoothly accommodate expansion and increasing levels of integration of separate controllers, facilitating modernization of industrial plants without large capital outlay. This book deals with the ways in which Ada can be used for such distributed systems. The main part of the book is devoted to the issue of how to construct and run an Ada program for a variable target configuration of several microcomputers, interconnected through shared memories, multi-access busses, local area networks or end-to-end lines. It is recognized that Ada and current Ada Programming Support Environments (APSEs) do not address distributed targets, and different approaches are therefore considered for coping with distribution without changing the language or unduly restricting the way in which it is used. The approach which emerges as the most natural is one where the designer is required to cluster tightly coupled Ada tasks into 'virtual nodes'. The implications of this approach for the user and the APSE are examined in detail, and further implications concerning use of the multi-microprocessor approach to achieve reliability and extensibility are also studied.