A System is a collection of interrelated componets that work together 
      to achieve some objective.

  2.1 Systems and their environment
        Two reasons why system engineers must understand the environment of a system : 
                (1) The reason for the existence of a system is to make some changes in its 
                   environment.
                (2) The functioning of a system can be very difficult to predict.
  
  2.2 System procurement
        -. System procurement  is the process of  acquiring a system for  an organization to 
          meet some identified need. 
        -.  It may  be necessary  to  complete some  system specification  and  architectural  
          design before procurement decisions are made. 
           There are two main reasons for this :
                (1) To  buy or  let a contract  to design  and build a  system, a  high-level  
                  specification of what that system should do must be completed.
                (2) It is almost always cheaper to buy a system than to design, manufacture 
                  and build it as a seperate project.

  2.3 The system engineering process
        -. Distinctions between the system engineering process and this sofrware process :
                (1) Interdisciplinary involvement.
                (2) Reduced scope for iteration between phases.
        -. System requirements definition
                (1) Coarse-grain functional requirements.
                (2) System properties.
                (3) Characteristics which the system must not exhibit.
        -. To provide  a fire and intruder  alarm system for the building  which will provide 
          internal and external warning of fire or unauthorized intrusion.
        -. To ensure that  the normal functioning of the work carried out  int the building is 
          not seriously disrupted by events such as fire and unauthorized intrusion.
        -. System desing
                (1) Partition requirements.
                (2) Identify sub-systems.
                (3) Assign requirements to sub-systems.
                (4) Specify sub-system functionality.
                (5) Define sub-system interfaces.
        -. Problems that can arise during system installation are :
                (1)  Proposed changes  have  to  be analysed  very  carefully both  from  a   
                   business and a technical perspective.
                (2) Because sub-systems are  never independent, changes to one sub-system 
                   may adversely affect the performance of another sub-system.
                (3) The reasons for original design decisions are often unrecorded.
                (4) As  systems age, their structure  typically becomes corrupted  by change 
                   so the costs of additional changes increase.

  2.4 System architecture modelling
        -. Functional system components
                (1) Sensor components.
                (2) Actuator components.
                (3) Computation components.
                (4) Communication components.
                (5) Interface components.

  2.5 Human factors

  2.6 System reliability engineering
        In a system, there are three closely related influences on the overall reliability :
                (1) Hardware reliability.
                (2) Software reliability.
                (3) Operator reliability.