System Lifecycle - ICT

Feasability study, Analysis, Design, Testing, Implementation, Evaluation.

(GCSE Level)

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  • Created by: Grace
  • Created on: 08-06-11 21:54

Feasibility Study

This is the first stage wherethe company decide whether a system lifecyle is needed and whether the cost will reach certain benefits.

At this point the company have the option to:

1. Not update their system

- cost is small/non existent, less reliable and may be out dated

2. Half update their system

- cost is moderate, overall system improvement by 30%

3. Complete overhaul

- cost is high, overall system improvement by 70%

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Investigation

This stage is approached when/if the company decide to complete the system lifecycle and agree that they will recieve more benefit over cost.

They must investigate what the current problems are and how they can be solved.

They also learn how their current system works via conducting:

  • Questionnaires
  • Observation on employees at work
  • Interviews

The company want to know what happens to documents and information at each stage so they make:

  • flow diagrams - to see how documents flow through the system
  • system diagrams - to see how systems link and interact
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Analysis

At this stage the company should have a good idea about what the problems are and what changes have to be made in order to overcome them.

The 'Analysis' stage presents the company with options,which may be:

  • Incorporating the current system's good bits in the updated system.
  • Buy an 'off the shelf' solution, this is just a general piece of software.
  • Create a bespoke system, which fits into the company's needs exactly.
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Design

The next stage is designing the new system. This stage requires the company to decide upon:

  • Screen layout
  • What the error messages will say
  • Navigation techniques
  • Menu buttons
  • Font, size and colour
  • Documents that can be printed
  • What hardware will be needed.

During this stage, the requirements specification and system specification will be created

-Requirements specification: details of how the system will operate, how data will be managed within it and what it will look like.

-Systems specification: details of the hardware and software that will be needed.

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Development

This stage requires the software programmers to follow the design stage to obtain a new system. 

the main things that are taken into account are:

  • A team to ensure that the hardware and software have been purchased and are put in place to be used.
  • Programmers write and test the code for the system
  • A team of people will be gathered in order to test the system after this stage, they will begin to write a test plan.
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Testing

By now the system has been created and requires an in depth testing scheme to ensure it works to it's potential.

Examples of what is tested:

  • Opening and closing of the system
  • Saving of work
  • Printing of work
  • Location of saved data
  • When something is wrong an error message will appear
  • Unnecessary data is deleted/removed
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Implementation

After the testing is completed the new system needs to become available to all employees in the company.

it can be installed in 3 ways:

1. Switch off old system and switch new one on. this is the simplest scenario, but information inputted in between the switch over may be lost.

2. Run the new and the old system parallel for a period of time. This lets the old system absorb the information and put it onto the new one.

3. Introduce the system to a couple of branches of the company may be done in order to see how the employees cope with the new system and fixing any problems. this may help them to decide which of the above to do on the rest of the branches.


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Evaluation

Now that the system is running it needs to be evaluated.

Two questions are taken into consideration, and they are:

Does the new system do what it is supposed to do?

Does it solve the original problem?

These are answered by looking back on the requirement and system specifications and seeing how it compares to the actual system.

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Maintenance

All systems need to be maintained, making sure the system continues to function correctly ( errors corrected, modifications made, documentation kept up to date).

Also, it needs to be cleared every so often of all the information it does not need, if it doesn't already do so itself.

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