7.2 Diagrams for Functionally Structured Methods
7.2.1 Context Diagrams
The purpose of a context diagram is to show the relationship between the system software and its environment. It portrays the complete system in its simplest form: a set of external items connected to a software black box, as shown in Figure 7.1(a):
Figure 7.1: Context diagram — functional flow diagram notation
It contains:
- A single unit representing the complete software system
- The external items that this software interfaces with
- Signal/data flows into and out of the software
The result of applying these ideas to a hypothetical anti-skid braking system is shown in Figure 7.1(b). This would be used in concert with the system operational description contained in the SOR document. Details concerning system behavior, signal levels, required response rates, and so on are normally tied in with the context diagram documentation.
The information presented in...
