MCS 014 Important Questions and Notes PdF for Exams SAD 2021

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MCS 014 System Analysis And Design Important Questions and Notes 

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MCS-014 Notes 


Unit 3 – Process of System Development 


➢ System Development Life Cycle 

The system development life cycle (SDLC) is a common methodology for system development in many organizations, featuring various phases that mark the progress of the system analysis and design effort. For example, in any given SDLC phase, the project can return to an earlier phase, if necessary. If a commercial product does not perform well just after its introduction, it may be temporarily removed from the market and improved before being re-introduced


• Waterfall Model - The waterfall Model illustrates the software development process in a linear sequential flow. This means that any phase in the development process begins only if the previous phase is complete. In the waterfall model, the phases do not overlap. Fig 3.1 shows waterfall model. 

• Iterative or Prototyping Model - An iterative life cycle model does not attempt to start with a full specification of requirements. Instead, development begins by specifying and implementing just part of the software, which is then reviewed to identify further requirements. This process is then repeated, producing a new version of the software at the end of each iteration of the model. 


• Spiral Model - The spiral model combines the idea of iterative development with the systematic, controlled aspects of the waterfall model. This Spiral model is a combination of iterative development process model and sequential linear development model i.e. the waterfall model with a very high emphasis on risk analysis. The spiral model has four phases (Identification, Design, Construct or build and Evaluation and Risk Analysis). A software project repeatedly passes through these phases in iterations called Spirals. 





Important Question – 

Explain how both waterfall model and prototyping model can be accommodated in the spiral process model?

The waterfall model is ideally used when the risk in the specification is low resulting in no need of risk resolution measures like prototyping. In this case, the second quadrant based activities of the spiral model are skipped. The Prototyping model is ideally used when the specification phase is less and the prototyping or risk resolution is quite high. The third quadrant based activities of the spiral model are skipped or have reduced scope. 


➢ Phases of SDLC

 SDLC consists of mainly seven steps. These are: 


1. Project Identification and Selection - The first phase in the SDLC is called project identification and selection. In this phase, the user identifies the need for a new or improved system. In large organizations, this identification may be part of a systems planning process. The outcome of the project identification and selection process is a determination of which systems development projects should be undertaken by the organization at least in terms of an initial study. 


2. Project Initiation and Planning - The second phase is project initiation and planning. The problems that are identified should be investigated and a decision to implement the information system or not for the organization should be taken. The project leader customizes the standardized SDLC and specifies the time and resources needed for its execution. 


3. Analysis - Analysis is the next phase. During this phase, the analysis has several sub-phases. The first is requirements determination. In this sub-phase, analysts work with users to determine the expectations of users from the proposed system. Next, the requirements are studied and structured in accordance with their interrelationships and eliminate any redundancies. Third, alternative initial design is generated to match the requirements. In this phase, feasibility study of the proposed system is also performed. Various types of feasibilities are: 

• Technical feasibility 

• Economic feasibility 

• Behavioural feasibility 

• Operational feasibility 

• Legal feasibility 

• Time feasibility. 


4. Logical Design - Logical design is not tied to any specific hardware and systems software platform. Logical design concentrates on the business aspects of the system. 


5. Physical Design - In physical design, the logical design is turned into physical or technical specifications. For example, you must convert diagrams that map the origin, flow, and processing of data in a system into a structured systems design. During the physical design, the analyst team decides the programming language in which the computer instructions will be written in, which database system and file structure will be used for the data, the platform that will be used and the network environment under which the system will be run. 


6. Implementation - During implementation, you turn system specification into working system that is tested and put into use. Implementation includes coding, testing and installation. During coding, programmers write programs that make up the system. Installation of the system can be done in the following three ways: 

• Direct conversion: In this type of conversion, the software is directly installed at user’s site. 

• Parallel conversion: In this type of conversion, both the old and new systems are run in parallel for some time. After monitoring the new system is implemented replacing the old one. 

• Phased conversion: In this type of conversion, the system is installed module by module. 


7. Maintenance - The final phase is maintenance. When a system is operating in an organization, users sometimes find problems with how it works and often think of better ways to perform its functions. During maintenance, programmers make the changes that users ask for and modify the system to reflect and support changing business conditions. These changes are necessary to keep the system running and useful. Maintenance is of three types: 

Corrective maintenance: In this type, the errors that creep into the system are removed. 

Adaptive maintenance: It is done to adapt with the changing external factors. For example, if the government rules change regarding the Dearness Allowance from 52% to 58%. 

Perfective maintenance: This is done to satisfy the users’ requirements to make the system more and more perfect. 


Questions related to unit 3: 


What are different phases in SDLC ? Also explain the need of SDLC for proper development of a system. 

Explain how both waterfall model and prototyping model can be accommodated in the spiral process model. 

Explain waterfall model with the help of a diagram. How is it different from spiral model ? Explain the merits and demerits of both the models. 

Explain the advantages and disadvantages of the following software development models 

(i) Waterfall 

(ii) Prototype 

(iii) Spiral 

Waterfall Model – Advantages 

• Simple and easy to understand and use 

• Easy to manage due to the rigidity of the model. Each phase has specific deliverables and a review process. 

Waterfall Model - Disadvantages 

• No working software is produced until late during the life cycle. 

• High amounts of risk and uncertainty. 

Iterative Model - Pros 

• Some working functionality can be developed quickly and early in the life cycle. 

• Results are obtained early and periodically. 

Iterative Model – Cons 

• More resources may be required. 

• Although cost of change is lesser, but it is not very suitable for changing requirements. 

Spiral Model - Pros 

• Changing requirements can be accommodated. 

• Allows extensive use of prototypes. 

Spiral Model – Cons 

• Management is more complex. 

• End of the project may not be known early.