1.1 INTRODUCTION Systems are created to solve problems. One can think of the systems approach as an organized way of dealing with a problem. In this dynamic world, the subject System Analysis and Design (SAD), mainly deals with the software development activities. 1.2 OBJECTIVES After going through this lesson, you should be able to define a system explain the different phases of system development life cycle enumerate the components of system analysis explain the components of system designing 1.3 DEFINING A SYSTEM A collection of components that work together to realize some objectives forms a system. Basically there are three major components in every system, namely input, processing and output. Input Output
Fig. 1.1: Basic System Components
2 :: Computer Applications
In a system the different components are connected with each other and they are interdependent. For example, human body represents a complete natural system. We are also bound by many national systems such as political system, economic system, educational system and so forth. The objective of the system demands that some output is produced as a result of processing the suitable inputs. A well-designed system also includes an additional element referred to as ‘control’ that provides a feedback to achieve desired objectives of the system. 1.4 SYSTEM LIFE CYCLE System life cycle is an organizational process of developing and maintaining systems. It helps in establishing a system project plan, because it gives overall list of processes and sub-processes required for developing a system. System development life cycle means combination of various activities. In other words we can say that various activities put together are referred as system development life cycle. In the System Analysis and Design terminology, the system development life cycle also means software development life cycle. Following are the different phases of system development life cycle: Preliminary study Feasibility study Detailed system study System analysis System design Coding Testing Implementation Maintenance The different phases of system development life cycle is shown in Fig. 1.2 below. System Study Maintenance Implementation Testing Software Development Life Cycle Feasibility Study System Analysis System Design
Coding Fig. 1.2: Phases of System Development Life Cycle
Introduction to System Analysis and Design :: 3
INTEXT QUESTIONS 1. Write True or False for the following statements. (a) A collection of components that work together to realize some objectives forms a system.
(b) System life cycle is not an organizational process of developing and maintaining a system. (c) In the system analysis and design terminology the system development life cycle means software development life cycle.
(d) Coding is not a step in system development life cycle. (e) System analysis and system design are the same phase of system development life cycle.
1.5 PHASES OF SYSTEM DEVELOPMENT LIFE CYCLE Let us now describe the different phases and related activities of system development life cycle. (a) Preliminary System Study Preliminary system study is the first stage of system development life cycle. This is a brief investigation of the system under consideration and gives a clear picture of what actually the physical system is? In practice, the initial system study involves the preparation of a ‘System Proposal’ which lists the Problem Definition, Objectives of the Study, Terms of reference for Study, Constraints, Expected benefits of the new system, etc. in the light of the user requirements. The system proposal is prepared by the System Analyst (who studies the system) and places it before the user management. The management may accept the proposal and the cycle proceeds to the next stage. The management may also reject the proposal or request some modifications in the proposal. In summary, we would say that system...