Software FMEA


No known method of software failure mode effects analysis--- some work has been done on
Sofware FTA a top down approach---
Bottom up approach means all known failure modes must be modelled.
SIL does not have metric or tools to analyse software for saefty,
it instead applies best practises and constraints on computer language features (i.e.
in C limited use of pointers  no recursion etc).


Introduce concept of FMEA
* bottom up
* all failure modes for all componnts

Concept of FMMD

Look at the structure of software
* a natural hierarchy

Software written for  a controlled
Contract programming
* describe concept
* describe how this fits in with failure modes and failure symptoms concepts

Describe how contract programming represents the failure modes of software

Now describe how this fis in with the structure of FMMD