GCSE ICT The Systems Life Cycle

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GCSE ICT The Systems Life Cycle

• Year 10

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The Systems Life Cycle

• Objectives
• To learn the stages in the systems life cycle
• To understand the role of the systems analyst

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The systems life cycle
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Why introduce a new system?

• The current system may no longer be suitable for
  its purpose.
• Technological developments may have made the
  current system redundant or outdated.
• The current system may be too inflexible or
  expensive to maintain, or may reduce the
  organisations ability to respond quickly enough
  to customers demands.
• Better management information is required for
  decision-making.
• The provision of better customer service.

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The role of the systems analyst

• investigating and analysing the existing system
  to establish how things work currently
• performing a feasibility study to judge whether a
  new computer system is feasible
• designing the new system, specifying programs,
  hardware, and procedures to be followed
• testing and overseeing the installation of the
  new system
• making sure that all user and technical
  documentation is complete
• evaluating the performance of the new system to
  make sure it fulfils the requirements

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The feasibility study

• The purpose is to see if it is worth going ahead
  with a new system.

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Feasibility study questions

• What are the problems with the existing system?
• Can the problems be solved?
• How much will it cost?
• What is the scope of the project?
• What must the new system do?
• What are the benefits of a new system?
• What are the recommendations?

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The feasibility report

• The findings of the feasibility study are
  summarised in a document called the feasibility
  report.
• The report is shown to senior managers, who use
  it to decide whether or not to go ahead with the
  new system.

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The feasibility study
Technical feasibility Economic feasibility Legal
feasibility Operational feasibility Schedule
feasibility
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Analysis - Investigating the current system

• Interviewing staff
• Examining current business and systems documents
  and output.
• Sending out questionnaires and analysing
  responses
• Observation of current procedures, by spending
  time in various departments.

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Analysis Understanding the problems

• Identifying problems with the current system
• Identifying the needs of users
• Investigating similar systems elsewhere
• Investigating what input, processing and output
  are needed
• Establishing what tasks need to be completed
• Establishing deadlines for completion of tasks

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Analysis Tools

• Flow charts
• Data flow diagrams
• Structure diagrams

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Design

• The design stage looks at how the new system will
  be built.
• Ict systems can be broken down into
• Input Process Output
• This stage looks at the design of all three.
• When the design is complete, a document called a
  design specification is created.
• This is shown to users for their comments.

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The Design Specification

• The hardware platform (PC, mainframe)
• The software (off the shelf, bespoke)
• The outputs (hardware, reports)
• The processing (sorting, searching, grouping)
• The inputs (data capture, input devices)
• Storage (devices, method)
• Security and backup
• The user interface (GUI, command line)
• The modular design of each program in the
  application
• The test plan and test data
• Conversion plan
• Documentation including systems and operations
  documentation. Later, a user manual will be
  produced.

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Implementation

• Programs written, tested and documented
• Data loaded from old system to new system
• Staff trained on new system
• May be parallel running of both systems for a
  while or direct implementation or phased
  implementation
• System maintained by keeping it up-to-date,
  solving any problems and writing new programs
  when required.

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Testing

• As soon as a system is developed it should be
  checked against user requirements to ensure the
  system does everything the user wants.

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Testing Four stages

• System tested with data that contains no errors
  to see if it produces correct results.
• Known errors are introduced into the data to see
  how the system handles them
• Output is produced and checked
• Extreme data is entered to ensure range checks
  are included as part of validation

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Test plan
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Documentation

• Two types of documentation are produced
• User guide so that users can learn to use the
  system
• Technical documentation so that the system can
  be maintained

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Evaluation

• Does the system meet all user needs?
• Is it functioning correctly?
• Are any improvements needed?

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Maintenance

• Providing support for users
• Providing enhancements
• Creating patches (fixing bugs)
• Improving software (updates)