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System design is the most crucial stage of system development process as the design determines the success or failure of the system. System design involves:

1. Reviewing the system's informational and functional requirements and

2. Developing a model of the new system, including logical and physical specifications Of outputs, inputs, processing, storage, and procedures. Before we proceed to the designing of outputs, inputs, storage, processing. and procedures, it is worthwhile to go through the concept of and activities involved in logical and physical design. Figure 1 presents logical and physical design of a system.

Srinivas MBA : MIS : CH 9  2009 

182 Logical Design. Logical design, also known as conceptual design, lays out the components of the system and their relationship to each other as they appear to users. It shows what the system will do as opposed to how it is actually implemented physically; It contains input/output specifications, file specifications, and processing specifications. Input/output specifications describe the forms in which input data will be required and the forms in which outputs will be presented to users. File specifications describe the way in which various files will be organized. Processing specifications describe the mode of data processing. . Physical Design. Physical design, also known as detailed design, translates the abstract logical design into specific technical design for the new system. It includes details of output design, input design, data storage design, processing design and procedure design. Physical design follows logical design as this stage converts the specifications developed at the logical level into specific technical design.

Output Design

Computer output refers to any information generated by a system whether printed or displayed. In fact, the main objective of a system is to generate information in a form which users can use. At the system analysis stage, the system development team identifies the outputs the proposed system should produce in order to satisfy the information requirements of the users. In designing outputs, the factors that should be considered are content, form, format, volume and timeliness. Content refers to the actual pieces of information that should be provided to users. Form refers to the way in which the information is provided like

Srinivas MBA : MIS : CH 9  2009 

183 text, graphics, visual, audio, or a combination of these. Format refers to the manner in which information is physically arranged like tabular, running text, and so on. Volume refers to the details that should be provided, whether in summary form or details of all items included in a report. Timeliness refers to the time at which the information is provided. Output (information) may be presented to users either in printed form or screen display form, the two forms commonly used in business organizations. Printed or display can be either in tabular form or graphic form.

Tabular Form: In general, end-users are more accustomed in receiving information in tabular form. Financial data, sales data, production data, inventory data, etc. are generally presented in tabular form. Certain information in tabular form is more important and can be made more visible than in other form. In order that tabular information is meaningful, it should include the following items :

1. Exceptions to normal expectations.

2. Major categories or groups of activities.

3. Summary of major categories or activities.

4. Unique identification information.

In the output design, tabular output should ensure the above items.

Graphic Form : In graphic form. information is presented in the form of charts.

Diagrams, bars, etc. which not only provide visual appeal but also ease the process of drawing inference from the information. For example, how much growth a business organization has achieved during the successive periods can be presented by bars where comparison can be made easily. Similarly, various components of cost of production can be shown by pie chart for meaningful inference.

Printed Form : Tabular and graphic presentation of information may be either in printed form or screen display form. Both require certain specific layout. A layout is the arrangement of items on the output medium. In preparing the layout of a printed report or document, certain guidelines should be followed:

1. Reports and documents should be designed to read left to right and from top to bottom.

2. The most important items of the report should be highly visible to locate.

3. Report/document should contain title. date of preparation, page number and column headings.

4. Each data item should have a heading which should be short but descriptive.

Data items that are related to each other should be grouped together in the report.

5. Control breaks should be used in the report to increase readability.

Control break reports are those in which repeating columns can be grouped together and exceptions can be highlighted.

6. Sufficient margin should be left on all sides of the report to enable the users to write their comments in case these are needed.

Screen Display Form : Sometimes. printed reports may not be required and inferences from the information can be drawn from looking it at the screen.

Srinivas MBA : MIS : CH 9  2009 

184 Designing of screen display layout begins with verifying the characteristics of the display screen. such as physical dimensions of the screen, number of rows and columns of data that can be displayed, degree, of resolution of colours, number of colours available, methods of highlighting-underline, bold, blinking, intensities, etc., and methods of intensity control. In designing screen display output, areas must be allocated to headings/titles, contents of the display, messages and instructions and explanation of the information if required.

Input Design

For generating outputs, matching inputs are required which requires input design.

Input design consists of developing procedures for data preparation, developing steps that are necessary to put data into a usable form for processing. and data entry. The objective of input design is to make data entry as easy, logical, and free from errors as possible. In input design, the focus is on computer operators and not on end-users. In entering data, operators need to know the following:

1. The allocated space for each field in the computer memory.

2. Field sequence which must match that in the data source.

3. The format in which the data fields are entered, for example, filling out the date field requires edited format-mm/dd/yy or dd/mm/yy.

In input design, many of the issues that are involved in output design are also involved here, such as content, form, volume, timeliness, etc. For capturing input data. different devices can be used, such as keyboard, online entry without using keyboard, and source data automation-scanners, voice input devices and sensors. The input design should take these devices into consideration. When keyed input system, which is most common, is used, it requires form design, coding, and data entry.

Form Design : Forms are printed papers that are filled by those persons who supply the information. Since forms are used as data source, these must be designed properly. In designing forms, following guidelines should be followed:

1. Contents of the form should be in the same sequence in which the data are entered in the computer.

2. Forms should be divided in logical sections. such as headings, identification and access, instructions, body, comments, verification, and signature with date.

3. Forms should be created to serve one or more purposes in recording, processing, storing, and retrieving information for various businesses.

4. Forms should be designed in such a way that these ensure correct and speedy completion.

Coding : Coding is the process of assigning codes to lengthy descriptions. A code is a brief number, title, or symbol that denotes a particular description.

Coding is required because a computer has limited memory and if detailed descriptions are used for inputs, they will occupy memory unnecessarily. For example, instead of using business-to-business as input, its code B2B is used as input, or business-to-consumer is coded as B2C, and so on. Although coding methods may exist in manual system also, it is usually necessary to modify these

Srinivas MBA : MIS : CH 9  2009 

185 to suit computer capabilities since human beings can work with bad and unorganized coding but not the computer.

Designing Data Entry : Designing of an efficient data entry method is a pre-requisite for the system being successful. To the extent data entry can be made automatic, there would be speed and accuracy. While keyed data input is more common, other source data automation devices, such as magnetic ink character recognition (MICR) device, optical character recognition (OCR) device, pen-based input device, etc. can be used for data input. Apart from using various devices to improve the quality of data entry, input validation can also be used for this purpose. The system designer may assume that data entry errors will occur.

Storage Design

In every information system, data storage is required for concurrent use as well as for future use. There can be two approaches for designing data storage system. First, data can be stored in individual files with one file for each application. Second, a database can be developed which can be shared by different users as the need arises. Further, database can be either centralized or distributed. While a file system may be more effective because separate files are designed for specific programs, this method tends to create data redundancy.

Therefore, this method is more suitable for smaller organizations having limited number of applications. In larger organizations, where the number of end-users is quite large and computer networking system is followed, database method is more appropriate. This method allows different users to use data in different forms.

Processing Design

Processing design focuses on the design of software resources, that is, the programs needed by the proposed information system. It involves developing detailed specifications for the program modules. Processing design produces detailed program specifications to meet user interface. Processing design must also produce specifications that meet the control and performance requirements developed in the analysis stage. Software to be used for data processing may be either developed in-house or can be procured from the market depending on the information technology capability of individual organizations.

Procedure Design

Procedure design specifies how the computer will function from data entry stage to output stage. The procedure indicates the logic of data processing and flow of the system control step by step. The steps in the procedure are shown in the computer system flow chart. The broad steps in the procedure are as follows:

1. Data entry-as per the input design specifications.

2. Data validation-as per the data validation specifications controlling data errors and absence of required data.

3. Transaction validation-preventing the entry of wrong transactions.

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186 4. Edit and update-completing records before data processing through data editing and updating.

5. Data processing-sorting. merging. collating. and computing data.

6. Output processing-indicating whether output is to be printed, displayed, or stored.

Documentation

After completion of system analysis and design, documentation is required.

Documentation describes how an information system works from both a technical and end-user standpoint. It is a written record of different phases of a system development and establishes design and performance criteria for these phases.

Lack of proper documentation often leads to system failure. Therefore, documentation should be done carefully. Since, documentation provides detailed procedures of how a system works, such procedure should be prescribed for all types of personnel who come in contact with the system. These personnel are end-users, secondary users, computer operating personnel, and trainers.

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