14.3 System Functional Specifications
14.3.1 Overview
System functions are described broadly in three ways: block diagrams, functional diagrams, and requirements specifications, as in Figure 14.7.
14.3.2 Block Diagram Description
These are high-level documents, designed to give an overview of the total system. They consist of a series of block diagrams, augmented with text, with their primary purpose being to describe the system operation. In large or complex systems, these need to be expanded using a series of subsystem descriptions. Their purpose is to do the following:
- Give a comprehensive description of the total system function and operation.
- Define the physical (hardware) composition of the total system.
- Identify the processor-based units within the total system.
- Define the operational features of all human-computer interfaces (HCIs).
- Identify electronic communication methods used within the system.
