System Life Cycle
INTRO
Evaluation
Maintenance
Testing
Design
Implementation
Development
Diagrams
Analysis
Investigation
Feasibility
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why is a new system needed
This is so that in a business, or anywhere else, a new system will be more helpful for them to carry out tasks
A system analysis is to be performed regularly to ensure that there are no casualties in the current system.
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During this stage, the company will decide whether there is a need for the system and if the cost of it can be justified
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alternatives to choose from
Company makes alterations to half the system
Complete overhaul
Change nothing:
Performance: No change, system remains outdated. Process becomes increasingly less efficient.
Benefit: Best parts of the system are kept, whilst the least efficient parts are redesigned to improve performance.
Benefit: No disruption to the business. Least cost.
Performance improvement: 30%
Cost: High, given that new equipment / software will be required. Training for staff needed.
Cost: Moderate, training moderate.
Benefit: Reduces running costs for the company (more profitable).
Performance: 70% improvement over the old system in time.
Techniques used to analyze about the current system
Interview
Observing others doing their job
Questionnaire
Finding out what happens to the document at every stage
Data Flow Diagrams
Process Diagrams
System diagrams
These show the relationships between the various systems in the company (or even outside if relevant) - how they interact, what depends on what and so on.
Most systems deal with information in one way or another. What really matters is how the information flows through the system.
People handle information in a specific way - they have a 'process'. For example, an employee makes an expense claim. First of all their manager counter-signs the claim. It then goes to the account manager who authorises payment and so on.
A process diagram will try to show these processes in action.
The analysis phase is where you look at alternative solutions which could be used to solve the problems.
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Here are some of the decisions that are taken during the design phase:
The error messages are written
The way that you will navigate from one page to another is defined
The screen layout is designed
9)
The system opens and closes properly
Work can be saved
2) You run the old and new system in parallel for a time.
3) You run only part of the new system
1) Switch off the old system and switch on the new.
Does the finished system do what it is supposed to?
Does it solve the problem that was found in the first place?
Staff or developers will identify parts of the system which could be tweaked to work more efficiently.
Over time, bugs will be discovered that weren't picked up in the testing. These will need to be fixed.