GCE A/L ICT Unit 7 - System Analysis & Design
Unit 7: System Analysis & Design is one of the most important units in GCE A/L ICT (Sri Lanka Local Syllabus). It is heavily tested in MCQ, structured, and essay questions.
1. Information Systems
Definition: An Information System is a collection of people, hardware, software, procedures, and data that work together to process data into meaningful information.
Key Idea
Input → Processing → Output (Information)
2. System Development Life Cycle (SDLC)
SDLC is a structured process used to develop information systems efficiently.
- Planning
- Feasibility Study
- System Analysis
- System Design
- Development
- Testing
- Implementation
- Maintenance
3. Feasibility Study
- Technical: Technology availability
- Economic: Cost vs benefit
- Operational: User ability
- Legal: Law compliance
- Schedule: Time management
4. Fact Finding Techniques
- Interviews
- Questionnaires
- Observation
- Document Study
5. Data Flow Diagram (DFD)
A Data Flow Diagram (DFD) is a graphical representation of how data moves through a system.
DFD Symbols
- Circle → Process
- Arrow → Data Flow
- Rectangle → External Entity
- Open Rectangle → Data Store
6. DFD Past Paper Questions (Very Important)
Question 1
Q: Draw a Context Diagram for a Library Management System.
Answer: A single process representing the whole system connected to external entities like Student and Librarian.
Explanation:
A context diagram is the highest level DFD showing system boundaries and external interactions only.
Question 2
Q: Draw Level 0 DFD for a School Admission System.
Answer: Includes processes like Receive Application, Process Application, and Generate Admission Result.
Explanation:
Level 0 DFD breaks the system into main processes and shows data flow between them.
Question 3
Q: Identify symbols used in DFD.
Answer:
- Process → Circle
- Data Flow → Arrow
- External Entity → Rectangle
- Data Store → Open Rectangle
Question 4
Q: Differentiate Context Diagram and Level 0 DFD.
| Context Diagram | Level 0 DFD |
|---|---|
| Shows whole system as one process | Breaks system into sub processes |
| No internal processes shown | Internal processes shown |
7. System Testing
- Unit Testing
- Integration Testing
- System Testing
- Acceptance Testing
8. System Conversion Methods
- Direct Changeover
- Parallel Running
- Pilot Running
- Phased Implementation
9. Maintenance Types
- Corrective Maintenance
- Adaptive Maintenance
- Perfective Maintenance
Exam Focus Areas
- SDLC (Very Important)
- DFD Drawing (Most Repeated)
- Feasibility Study
- Testing Methods
- Conversion Methods
Exam Tips
- Practice DFD drawing daily
- Memorize SDLC stages
- Focus on past paper patterns
