2IntroductionComputers are used in all areas of business, industry, government, education, transport, medicine, everywhere. Each one of these applications arose as someone’s solution to a problem.Solving a problem may be seen as a number of main stages. In producing a solution, a new information system is developed.
3System Life CycleThe sequence of steps in developing a new system to solve a problem is called the system life cycle.A systems analyst analyses existing systems and develops new ones.
4System Life Cycle The main steps in the system life cycle are: problem recognition;feasibility study;analysis of the problem;design of a new system;construction of the new system;conversion from the old system to the new;maintenance and review of the new system.
5Problem RecognitionProblem Recognition establishes what exactly the problem is. It is a preliminary study of the situationYou would study the following;A situationA userA problem
6Feasibility StudyA feasibility study establishes whether or not a new system is a good idea, and estimates the time and resources required to develop it.Management has to approve the feasibility report before the project can go ahead.
7Analysis of the problem Once permission to go ahead an analysis is done to:Study the existing system - interview users of the current system, read any manuals or instructions that are in use and observe the system in operationWork out what the new system requires.Decide what the new system has to do.
8Design of the new system At the design stage:different possible solutions are considered;it is decided whether new software and hardware is required;a design is prepared of the new system including: data capture, type of user interface, validation methods, data files, output and security.diagrams produced include: system flowcharts and program flowcharts or structure diagrams.
9Construction of the new system Construction of the new system includes:writing new programs;system testing and debugging;acceptance testing;producing technical and user documentation;users are trained to use the new system
10Conversion to the new system Software and hardware needs to be installedFiles need to be convertedConversion can be carried out as:a direct change over;parallel working;a phased introduction.System maintenance and reviewRepair faults;Monitor and solve problems;Upgrade as requirements change
11EXAM QUESTIONSJean has to write a program that helps young children to add and subtract.Suggest three things Jean should do to improve her understanding of what the children need.Give three pieces of advice to Jean to help her to design the program specially for the children.Grade DDescribe the following stages involved in producing an information system:DesigningTestingGrade C
12EXAM QUESTIONSA computer is being installed in a theatre to deal with bookings. It is to replace the manual system used for bookings.Give three activities which a systems analyst should carry out when analysing an existing system.When the system is installed parallel running takes place.What is parallel running?When is it no longer necessary?Grade C