Detailed Design

Introduction

• The design translates the system requirements into ways of operate them.

• The design is a solution, a “ how to “ approach, compared to analysis, a “what is” orientation.

• The design phase focuses on the detailed implementation of the system recommended in the feasibility study.

Modularization

• One way to plan a new system is to focus on each functional subsystem as a separate entity or application area.

• Using such an approach, each application area is treated as if it were totally independent.

• The modular systems approach divides each application area into a number of smaller units called modules.

Advantages Of Modularization• speed up the systems process.

• eliminates unnecessary duplication.

• result in higher quality.

• provides better control over the total system project.

• allows flexibility as additional features may be added later.

• parts of the system can be tested separately.

limitations Of Modularization• Numerous unique application requirements

which must be incorporated in common modules. If a single module is to accommodate all situations, it will become very large & complex.

• Modular systems design is best viewed as one aspect of a broader planning issue, but it is not a required step in the design process.

• changes and errors affect common modules, the negative consequences can be widespread

Input Design

• Inaccurate input data are the most common cause of error in data processing.

• Errors entered by operator can be controlled by input design.

• Input design is the process of converting user-originated inputs to a computer based format.

Goal of input design

• The goal of designing input data is to make data entry:-

• Easy

• Logical

• Error free.

Input media and devices

• Keyboard• Mouse• Touch Screen• Point-of-sale terminals• Sound and speech• Automatic data capture

• Optical mark recognition (OMR)• Bar codes

• Optical character recognition (OCR)• Magnetic Ink• Electromagnetic transmission• Smart cards

Data input methods

• ON-LINE - User directly Enters data using screen prompts.

• OFF-LINE -Forms filled by users- for example-candidates for admission to a college fill forms

OFF LINE DATA ENTRY –PROBLEMS• It is not always possible for the form to give

message when input is wrong, error may be found after elapse of time period. Therefore, good controls of automatically detect and if possible correct errors is required.

ON LINE DATA ENTRY –PROBLEMS1. Errors in on-line data entry due to poor

screen design. System should inform the user immediately when wrong data is input.

2.Errors in off-line data entry due to bad form design and human errors by users and data entry operator.