Sunday, February 17, 2013

System Design


System Design
1.  System Model:
A logical or mathematical representation of a system is known as system model.
Model can be built for the existing system to better understand the proposed system.
2.  Process Modelling:
Process modelling is technique which involves graphical representation of functions or processes that capture , manipulates, stores or distribute data between a system & its environment or among components within a system. DFD(Data Flow Diagram) is one of the common form of process model.
3.  Logical & Physical design:
System design involves two categories-
a.  Logical design:
It is concerned with the specification of major features of the system that would meet the objectives. The delivered product of logical design may be called as a blueprint of a new system.
Logical design of a system includes content requirements and some of following components-
                                                                   i.            Output(Reports & Displays)
                                                                 ii.            Input forms
                                                              iii.            Procedures(Structured of procedures to collect, transforms & output data)
                                                              iv.            Storage(Requirements for data to be stored in the database)
                                                                 v.            Control(Requirements for data integrity, security & procedure for recovery)
b.  Physical design:
It requires logical design or blueprint and produces the program specification, physical files or database definitions. It also includes user interface design and selects hardware & software packages.

4.  Input Output Design:
a.  Input Design:
Part of the system which deals with the design of the interface through which user communicates with the system and feeds the input data to the system.
b.  Output Design:
The part of the system which deals with determining how the output is to be presented, in what format or shape is known as output design of the system. Computer produces displays and print reports that are to be read and used by users therefore the output must be clear and easy to understand.

c.   I/O Forms:
It is primary carrier for data or information. They are the user requests for some action. A properly designed form is necessary for efficient functioning of a system.
Form is used to –
                                                                   i.            To obtain information efficiently
                                                                 ii.            Distributes information easily
                                                              iii.            Store information effectively and economically
            Types of Forms:
1.  Action Form:
This type of form requests the user to perform certain actions and they are generally moves from one person to organisation or another person.
2.  Memory Form:
It record historical data such as stock ledger, purchase record, bond form.
3.  Report Form:
It provides summarised information. These are generally used by managers and such people who are required to make decision making. They guide supervisors and administrators for decision making.

Form designing:
Steps for form designing-
                                                                               i.            Define the purpose of form
                                                                             ii.            Specify its data contents
                                                                          iii.            Using a guide sheet enter title, form number and indicates position of any specially located material
                                                                          iv.            Review with the user & revised if necessary
                                                                             v.            Create few test forms.

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