Demonstration of Advanced Reliability Techniques for Safety-Related Computer Systems

DARTS - 2354

Keywords safety-critical software, software certification, metrics

Start Date: 12-JUN-89 / Duration: 54 months

[ contact / participants ]

Objectives and Approach

The aim of DARTS is to facilitate the selection of reliable systems for safety-critical applications. It will do so by moving towards the establishment of a single, universally agreed method of certifying computer-based, safety-critical systems and by reporting the cost-effectiveness of various approaches to software reliability measurement. Accordingly, the objective of the project is to demonstrate the use of advanced reliability techniques for the selection of safety-critical computer systems.

DARTS is based on the design and licensing of a four-channel, safety-critical computer-based system. The development of the four diverse software versions will focus on a variety of methodologies, each using different tools and techniques, and each originating from different project teams. Four teams will each design of one of the channels, one will design the test environment, and two teams will act as licensing bodies. Once a licence has been granted, the prototype system will be installed in the test environment. An evaluation of comparative channel performance and of the selection process will be provided by monitoring system performance.

The main stages of the project are:

Progress and Results

After an initial study, a control application in a nuclear plant was selected, and the parameters drawn up to assign development work to the teams. All channels passed the simple acceptance tests and were delivered for integration into the demonstrator/test harness at AEA. The product and process data from the channels was collated and sent for consistency checking to AEA. Assessment data was also collected for subsequent analysis. The first phase of the system testing of the channels showed a number of errors that required repair before testing could continue. Preliminary analysis of the development data was carried out. Repairs to the channels were completed and a second phase of testing started. Analysis of the assessment data commenced with the production of system models and the use of the SLAT (Software Lifecycle Assessment Technique) to establish the risk of using a particular lifecycle. Phase two of the system testing was completed. The Prometrix tool was used to provide metrics of the product source code, allowing comparison of the source and the productivity achieved by the different lifecycles employed. In conjunction with the development and assessment it will be possible to establish the most efficient lifecycle used, the efficiency of the system testing and the strategies to be used in testing.


The system may be used to explore further different types of testing to promote increased reliability to be claimed for safety-critical software and computer-based systems in general. This could further establish optimum testing strategies, provide a vehicle for reliabiity growth assessment and examine overall reliability of back-to-back diverse systems.


Mrs J.A. Baldwin
AEA Technology
tel: + 44/ 305-251888 ext 2380
fax: + 44/ 305-631113479


AEA - UK - C
NE - UK - P
EDF - F - P
GRS - D - P

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DARTS - 2354, December 1993

please address enquiries to the ESPRIT Information Desk

html version of synopsis by Nick Cook