
6
General
introduction
design in the system is in the controlling program, and it is far from
easy to ensure that a series of instructions will always do exactly what
they are intended to. There are two particular points to observe.
Firstly, mistakes in a program are errors in
design.
The failures they
cause cannot be guarded against by duplication of the system (since
both sets of equipment would make the same error at the same time),
and they always come without prior warning.
Secondly, programming is an activity fraught with psychological
difficulty. It has been compared to compulsive gambling. Most people
are unreasoning optimists abou