Dependability of Critical Computer Systems 1

M. CARPENTIER Director General DG XIII, Telecommunications, Information Industries and Innovation of the Commission of the European Communities It is with great pleasure that I introduce and recommend this collection of guidelines produced by EWICS TC7. This Technical Committee has consistently attracted technical experts of high quality from all over Europe and the standard of the Committee's work has reflected this. The Committee has been sponsored by the Commission of the European Communities since 1978. During this period, there has been the opportunity to observe the enthusiasm and dedication in the activities of the group, the expertise and effort invested in its work, the discipline in meeting objectives and the quality of the resulting guidelines. It is no surprise that these guidelines have influenced the work of international standardisation bodies. Now the first six of EWICS TCTs guidelines are being made available as a book. I am convinced that all computer system developers who use them will greatly enhance their chances of achieving quality systems. v Acknowledgements In the preparation of this book, the editoLisgrateful to P. Bishop, G. Covington II, C. Goring, and W. Quirk for their help in editing the guidelines. In addition, he would like to thank S. Bologna, W. Ehrenberger, M. Ould, J. Rata, L. Sintonen and J. Zalewski for reviewing the chapters and providing additional material.

1 A Guideline for the Documentation of Critical Computer Systems.- 1 About this Guideline.- 1.1 Scope.- 1.2 Intended Audience.- 1.3 Main Topics.- 1.4 Tailoring.- 1.5 Relationship of this Guideline to Other Documents.- 1.6 References.- 1.7 Principles Determining the Documentation Set.- 1.8 Structure and Content of the Guideline.- 2 Documentation Guideline.- Topic 1: Management Documentation.- 1.1 Documentation structure.- 1.2 Documentation standards.- 1.3 Documentation maintenance.- Topic 2: System Requirements Specification (SRS).- Topic 3: System Description.- 3.1 The system.- 3.2 Hardware.- 3.3 Software.- 3.4 System operation and user aspects.- Topic 4: Technical Support Documentation.- 4.1 Verification, validation and test plans.- 4.2 Record of verification activities.- 4.3 Project development report.- Topic 5: Project Management Documentation.- 5.1 End-product specification.- 5.2 Technical approach document.- 5.3 Activity description.- 5.4 Risks and fallback documents.- 5.5 Dependency diagrams/network.- 5.6 Bar charts.- 5.7 Budgets.- 5.8 Project management and quality plans (PMQP).- Topic 6: Maintenance Documentation.- 6.1 Introduction.- 6.2 Maintenance organization.- 6.3 Maintenance procedures.- 6.4 Maintenance provisions.- 6.5 Maintenance equipment.- Topic 7: Operational Documentation.- 7.1 System overview.- 7.2 Operator interfaces.- 7.3 Tasks and procedures.- 7.4 Operator responsibilites and demands.- Topic 8: Additional Equipment and Software Documentation.- 8.1 Introduction.- 8.2 Management tools.- 8.3 Development documentation tools.- 8.4 Verification and validation tools.- 8.5 Operation tools.- 8.6 Interfaces with other systems and external costraints.- 8.7 Additional documentation.- 2 A Guideline for the Production of System Requirements Specifications.- 1 About this Guideline.- 1.1 Scope.- 1.2 Intended Audience.- 1.3 Main Topics.- 1.4 Tailoring.- 1.5 Terms & Definitions.- 1.6 Existing Requirements Specification Practice.- 1.7 Structure of an SRS.- 1.8 Relationship of this Document to Other Standards.- 1.9 References.- 2 About System Requirements Specifications (SRSs).- 2.1 Importance of SRSs.- 2.2 Purpose.- 2.3 Form.- 2.4 Areas Subject to Customer Requirements.- 2.5 Stability.- 2.6 Quality—What is a Good SRS.- 2.7 Standard SRS Outline.- 2.8 Life-Cycle of an SRS.- 3 The Form of a System Requirements Specification.- 3.0 Title.- 3.1 Contents.- 3.2 Introduction.- 3.3 About this Document.- 3.4 Definitions of Terms Used in this Document.- 3.5 Target System in Context.- 3.6 Target System Requirements.- 3.7 Target System Environment Requirements.- 3.8 Development Project Requirements.- 3.9 Development Project Environment Requirements.- 3.10 Acceptance Test Plans and Criteria.- 3.11 References.- 3.12 Appendices.- 3 A Guideline for the Development of Critical Software.- 1 About this Guideline.- 1.1 Scope.- 1.2 Intended Audience.- 1.3 Main Topics.- 1.4 Tailoring.- 1.5 Structure of the Guideline.- 2 About the Development of Critical Software.- 2.1 Guideline Approach.- 2.2 Approach to Software Design.- 2.3 The Development Process.- 2.4 Appropriate Programming Language and Compiler.- 2.5 Verification of Criteria Compliance.- 3 Detailed Guideline for the Design and Construction of Critical Software.- 3.1 Design and Construction Procedures.- 3.2 Structuring of Software.- 3.3 Program Self Checks.- 3.4 Detailed Design and Coding.- 3.5 Language-Dependent Considerations.- 4 Language, Translator and Linkage Editor.- 4.1 General.- 4.2 Error Handling.- 4.3 Data and Variable Handling.- 4.4 Timing Aspects.- 4 A Guideline for the Design and Production of Hardware for Safety-Related Computer Systems.- 1 About this Guideline.- 1.1 Introduction.- 1.2 Scope.- 1.3 Intended Audience.- 1.4 Main Topics.- 1.5 Existing Practice.- 1.6 Relationship of this Document to other Standards.- 1.7 References.- 1.8 List of Abbreviations.- 2 Safe Hardware.- 2.1 Aim.- 2.2 Methods.- 2.3 Types of Failures.- 2.4 Possibilities for Fail-Safe Systems, Including Computers.- 2.5 A Qualitative Safety Investigation on the Influence of and Protective Measures against Failures.- 2.6 A Quantitative Safety Investigation on the Influence of Failure-Detection Time and Failure-Detection Completeness.- 2.7 Special Programs for Failure Detection.- 2.8 Verification of the Checking Programs.- 2.9 Comparative Discussion of the Various Systems from a Fail-Safe Point of View.- 2.10 New Developments.- 5 A Guideline for the Verification and Validation of Critical Computer Systems.- 1 About this Guideline.- 1.1 Scope.- 1.2 Intended Audience.- 1.3 Assumptions.- 1.4 The Verification and Validation Process.- 1.5 The Verification and Validation Plan.- 2 The Verification and Validation Activities.- 2.1 Design Verification.- 2.2 Design Verification Report.- 2.3 Code Verification.- 2.4 Code Verification Report.- 2.5 Hardware/Software Integration Verification.- 2.6 Integration Verification Report.- 2.7 Computer System Validation.- 2.8 System Validation Report.- 2.9 Post-Certification Software—Change Verification and Validation.- 2.10 Related Standards and Guidelines.- 6 Techniques for the Verification and Validation of Critical Software.- 1 About this Guideline.- 1.1 Scope.- 1.2 Intended Audience.- 1.3 Classification.- 1.4 Format of the Survey.- 2 A Survey of Software Verification and Validation Techniques.- 2.1 Method Class 1: Analysis Tecniques.- 2.2 Method Class 2: Testing Tecniques.- 2.3 Method Class 3: Reliability Assessment.- 2.4 Method Class 4: Tests of Databases.- 2.5 References.