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Title:Safety-Critical Computer Systems

Author: Neil Story
ISBN: 0-201-42787-7
Cost: 21-95UKP
Disk: N/A

Safety critical is becoming part of the mainstream computing world as we saunter towards the millennium and some aircraft have control systems only marginally better than Ariane 5 . This book is aimed at anything that has computer control on it somewhere.


The more I looked at this book with definitions at every turn, from “reliability is...” to the various lists of categories from the safety standards of all sorts, the more I realised that this a university course in book form. The text is in short chapters each with simple examples in the text. There are references, further reading and exercises at the end of each chapter.


My test for this sort of book is to look at its language choice for safety critical work. Sure enough it suggests ADA, Pascal and Mod2 totally dismissing C (and C++). Academics tend to miss the point that a theoretically good language is one thing and a language with an industrial strength implementation with tool support is another. (I was once told, by a university lecturer, to use a Mod2 compiler because Mod2 was “safe”. The compiler was written in assembler. Assembler was going to be banned for MOD safety critical work because it was so unsafe.) The other “give away” is the chapter on formal methods so widely loved of universities but so little used in industry. Some of the assertions in the book have been overtaken by modern tools and methods.


The V life cycle model is discussed but the emphasis is on systems in the round rather than software. PLC’s are covered and there are case studies of a well know aircraft and power station. Refreshingly the sections on ethics and legal issues cover UK rather than US law. (Some major companies are due for a shock on 2-1-2000 when they discover the UK does not use US law!)


So this is an academic safety critical systems book for students. Is it of any use? Sorry, not for industrial use. When all examples, exercises and references are removed there is not a great deal of meat left. Those in industry will need more specific books with more depth. This is not a criticism, students need this sort of book as a starting point for which is fits the bill. It is remarkably good value for a hard cover book probably because there is a guaranteed market at least one university.