Title: Some notes on software failure Date: 24/Oct/2001 Author: Les Hatton The problem Software failure manifests itself in at least three important ways:- Process failure. Here the process of producing software fails in some fundamental way so that the wrong system is produced, or the right system is produced but very late, or even no system is produced at all. This has been a very common source of failure in all types of development. An example is the Taurus Stock Exchange system in the UK as well as a significant number of Government sponsored initiatives. The NHS has been rather blighted here. We are not alone. In the US, a study of $140 million worth of Flight Controls Software Projects 1985-1990 by the Audit Office of the US D.o.D. revealed that 90% was either never delivered or never worked. Product failure (cessation). Here the product fails when it is running leading to some adverse behaviour. There are numerous examples of this with a significant number of billion dollar failures occurring around the world in the 1990s, the first probably being the AT&T failure of January 1990 when a single mistake took down the entire US long-distance telephone network for 9 hours. In the last two years, most major car companies have had very expensive recalls because of mistakes in software controlled systems leading to unacceptable failures. Product failure (misleading results). Here the results of scientific research are erroneous because they are computer simulated by defective software. As an example of this, the main mathematical technique used for oil & gas exploration is fundamentally damaged by software failure, (Hatton & Roberts (1994), Hatton (1997)), with an unexpected drop to one significant figure of accuracy instead of the expected four and the necessary three. The evidence suggests that many other numerical simulations in science may be similarly affected. In aggregate, the cost of failure is now such as to be unquestionably damaging to the UK economy (as well as all other major economies) and a resolve to improve matters would be central to the global performance of the UK economy in IT and any dependent activity. It is a genuinely strategic issue. Aggravating factors Size. Software systems are growing by a factor of two every 18 months in consumer embedded systems. Today we have around 3,000,000 source lines in a car. © Copyright, Les Hatton, UKC, 2001, 24-Oct-2001 Page .. 1