91Ó°ÊÓ

In the insulin pump system, the user has to change the needle and insulin supply at regular intervals and may also change the maximum single dose and the maximum daily dose that may be administered. Suggest three user errors that might occur and propose safety requirements that would avoid these errors resulting in an accident.

What is the fundamental difference between hardware and software failures? Given this difference, explain why hardware reliability metrics are often inappropriate for measuring software reliability.

Explain why it is practically impossible to validate reliability specifications when these are expressed in terms of a very small number of failures over the total lifetime of a system.