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Analysis And Design } |
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| Systems Analysis and Design is an interdisciplinary part of science, which can related to: |
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Systems analysis
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Systems design
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System Analysis : |
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| Assuming that a new system is to be developed, the next phase is system analysis. Analysis involved a detailed study of the current system, leading to specifications of a new system. Analysis is a detailed study of various operations performed by a system and their relationships within and outside the system. During analysis, data are collected on the available files, decision points and transactions handled by the present system. Interviews, on-site observation and questionnaire are the tools used for system analysis. Using the following steps it becomes easy to draw the exact boundary of the new system under consideration: |
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| All procedures, requirements must be analysed and documented in the form of detailed data flow diagrams (DFDs), data dictionary, logical data structures and miniature specifications. System Analysis also includes sub-dividing of complex process involving the entire system, identification of data store and manual processes. |
| # The main points to be discussed in system analysis are : |
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Specification of what the new system is to accomplish based on the user requirements.
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Functional hierarchy showing the functions to be performed by the new system and their relationship with each other.
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Function network which are similar to function hierarchy but they highlight the those functions which are common to more than one procedure.
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List of attributes of the entities - these are the data items which need to be held about each entity (record)
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| # System Design : |
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| Based on the user requirements and the detailed analysis of a new system, the new system must be designed. This is the phase of system designing. It is a most crucial phase in the development of a system. Normally, the design proceeds in two stages : |
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| Preliminary or general design: In the preliminary or general design, the features of the new system are specified. The costs of implementing these features and the benefits to be derived are estimated. If the project is still considered to be feasible, we move to the detailed design stage. |
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| Structure or Detailed design: In the detailed design stage, computer oriented work begins in earnest. At this stage, the design of the system becomes more structured. Structure design is a blue print of a computer system solution to a given problem having the same components and inter-relationship among the same components as the original problem. Input, output and processing specifications are drawn up in detail. In the design stage, the programming language and the platform in which the new system will run are also decided. |
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| There are several tools and techniques used for designing. These tools and techniques are : |
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Flowchart
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Data flow diagram (DFDs)
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Data dictionary
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Structured English
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Decision table
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Decision tree
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