๐ GCE A/L ICT – UNIT 7
System Development & Programming Concepts
Complete exam-focused notes for Sri Lankan GCE Advanced Level ICT
๐ท 7.1 Introduction to System Development
๐น What is a System?
A system is a collection of interrelated components working together to achieve a common goal.
๐ Example: School Management System
| Component | Description |
|---|---|
| Inputs | Student data, attendance, marks |
| Processes | Attendance tracking, marks calculation, report generation |
| Outputs | Reports, results, certificates |
๐น Types of Systems
| Type | Characteristics | Example |
|---|---|---|
| Manual Systems | • Paper-based • Human-operated • Slower processing |
Attendance register, paper files |
| Computer-Based Systems | • Automated • Software-driven • Faster & accurate |
School ERP, Library Management System |
๐น What is System Development?
The process of creating or modifying a system to meet user requirements and solve problems.
๐ก Key Point: System development follows a structured approach called SDLC to ensure quality and efficiency.
๐ 7.2 SDLC – System Development Life Cycle
๐น Definition
SDLC is a structured, phased process followed to plan, create, test, and deploy an information system.
๐น The 7 Phases of SDLC
Planning → Analysis → Design → Development → Testing → Implementation → Maintenance
-
Planning
• Identify the problem/need
• Conduct feasibility study
• Define project scope & resources -
Analysis
• Study current system
• Gather user requirements
• Create Requirement Specification Document -
Design
• System architecture
• Database design (ERD)
• UI/UX mockups & DFDs -
Development
• Actual coding/programming
• Database implementation
• Module integration -
Testing
• Find & fix bugs
• Unit testing, system testing
• User acceptance testing (UAT) -
Implementation
• Install & deploy system
• Train users
• Data migration -
Maintenance
• Fix post-launch issues
• Apply updates & patches
• Add new features
๐น SDLC Example: Library System
| Phase | Activity |
|---|---|
| Planning | Identify need to manage books digitally |
| Analysis | Interview librarians, list requirements |
| Design | Create database schema + UI wireframes |
| Development | Code the system in chosen language |
| Testing | Test borrowing, returning, fine calculation |
| Implementation | Install in library, train staff |
| Maintenance | Fix bugs, add e-book feature later |
๐ฏ Exam Tip: Memorize the 7 phases IN ORDER. A common 4-mark question asks you to list them sequentially.
๐ 7.3 Feasibility Study (TEOS)
๐น Purpose
❓ Key Question: "Is this system worth developing?"
Feasibility study evaluates if the project is practical, affordable, and achievable.
Feasibility study evaluates if the project is practical, affordable, and achievable.
๐น Types of Feasibility (TEOS)
| Type | Key Question | Example |
|---|---|---|
| Technical ๐ง | Do we have the technology & skills? | Need mobile app developers, cloud server |
| Economic ๐ฐ | Do benefits > costs? | Cost: Rs.500k | Benefit: Rs.1M → ✅ Feasible |
| Operational ๐ฅ | Will users accept & use it? | Can teachers learn the new system easily? |
| Schedule ๐ | Can it be done on time? | Can we finish before next academic year? |
๐น Economic Feasibility Formula
Feasible if:
Expected Benefits > Development + Operational Costs
Example Calculation:
- ๐ธ Development Cost: Rs. 500,000
- ๐ Annual Benefit: Rs. 300,000 × 4 years = Rs. 1,200,000
- ✅ Net Gain: Rs. 700,000 → Project is feasible!
๐ฏ Exam Trick: If asked "Explain feasibility study", use the TEOS structure + one calculation example for full marks.
๐ท 7.4-7.5 Data Flow Diagrams (DFD)
๐น What is a DFD?
A Data Flow Diagram is a graphical representation showing how data moves through a system – from input, through processes, to output.
๐น DFD Symbols (MEMORIZE FOR EXAMS)
| Symbol | Name | Meaning | Example |
|---|---|---|---|
| ○ Circle | Process | Transforms input to output | "Calculate Marks" |
| ➜ Arrow | Data Flow | Movement of data | "Student Details" |
| ▭ Rectangle | External Entity | Source/destination outside system | Student, Admin, Bank |
| ▭▭ Open Rectangle | Data Store | Where data is stored | Database, File |
๐น Levels of DFD
๐ฏ Exam Focus: You MUST know Context Diagram (Level 0) in detail!
- Level 0 (Context Diagram): Entire system as ONE process + external entities
- Level 1 DFD: Breaks system into major sub-processes
- Level 2+ DFD: Further decomposition of processes
๐น Context Diagram – EXAM CRITICAL
✅ What it Shows:
- The whole system as a single process
- All external entities interacting with it
- Data flows between entities and system
๐น How to Draw: 4 Simple Steps
- Identify the System
Example:[ Student Registration System ] - Identify External Entities
Example:[Student][Admin][Examination Dept] - Map Inputs & Outputs
Entity Input to System Output from System Student Registration details Confirmation SMS Admin Course data Enrollment reports - Draw Labeled Arrows
[Student] → Registration Details → [System]
๐น Critical Rules (MCQ Gold)
✔ MUST DO:
- Only ONE process box (the whole system)
- NO internal processes or data stores
- ALL external entities must be shown
- EVERY arrow must have a clear label
- Arrows show direction of data flow
❌ AVOID THESE MISTAKES:
- Drawing multiple process circles ❌
- Adding database symbols ❌
- Unlabeled arrows ❌
- Missing key entities ❌
๐งฎ 7.6 Algorithms & 7.7 Flowcharts
๐น Algorithm Definition
An algorithm is a finite, step-by-step procedure written in simple language to solve a specific problem.
๐น Characteristics of a Good Algorithm
| Characteristic | Meaning |
|---|---|
| Finite | Must have a definite end point |
| Clear | Each step must be unambiguous |
| Logical | Steps must follow correct order |
| Effective | Must solve the problem correctly |
| Input/Output | Must have defined inputs & outputs |
๐น Algorithm Writing Rules (Exam)
- ✓ Use numbered steps (1, 2, 3...)
- ✓ Use simple, plain English (no code syntax)
- ✓ Start with INPUT and end with STOP/END
- ✓ Use IF-THEN-ELSE for decisions
- ✓ Keep each step atomic (one action per step)
๐น Example: Find Largest of 3 Numbers
1. INPUT A, B, C
2. IF A > B AND A > C THEN
3. PRINT "Largest is", A
4. ELSE IF B > C THEN
5. PRINT "Largest is", B
6. ELSE
7. PRINT "Largest is", C
8. END IF
9. STOP
๐น Flowchart Definition & Symbols
A flowchart is a graphical representation of an algorithm using standardized symbols.
| Symbol | Name | Purpose |
|---|---|---|
| ⬭ Oval | Terminal | Start/End points |
| ▭ Rectangle | Process | Calculation/action step |
| ◇ Diamond | Decision | Yes/No condition check |
| ➜ Arrow | Flow Line | Direction of execution |
| ▱ Parallelogram | Input/Output | Read data / Display result |
๐ก Exam Tip: Always label decision branches with "Yes/No"! Missing labels cost marks.
๐ป 7.8 Programming Concepts
๐น Variables & Data Types
Named storage locations that hold data values.
Example:
int age = 20;String name = "Student";boolean isActive = true;
๐น Basic Data Types
| Data Type | Stores | Example |
|---|---|---|
| Integer | Whole numbers | 25, -10, 0 |
| Float/Double | Decimal numbers | 3.14, -0.5 |
| String | Text characters | "Hello", "A/L 2026" |
| Boolean | True/False values | true, false |
๐น Operators
๐ข Arithmetic:
+ - * / %
⚖️ Comparison: == != > < >= <=
๐ Logical: AND(&&), OR(||), NOT(!)
๐ Assignment: = += -=
๐น Control Structures (CORE CONCEPT)
1️⃣ Sequence
Statements executed in order, one after another.
INPUT name
PRINT "Hello", name
CALCULATE total
PRINT total
2️⃣ Selection (Decision)
Execute different code based on a condition.
IF-ELSE Example:
IF marks >= 50 THEN
PRINT "PASS"
ELSE
PRINT "FAIL"
END IF
3️⃣ Iteration (Loop)
Repeat a block of code multiple times.
FOR Loop Example:
FOR i = 1 TO 10 STEP 1
PRINT i
NEXT i
๐งช 7.9 Testing & Debugging
๐น Testing vs Debugging
| Testing | Debugging |
|---|---|
| • Finding errors/bugs • Done BEFORE release • Uses test data |
• Fixing identified errors • Done AFTER testing • Requires code analysis |
๐น Types of Testing
| Type | Purpose | Example |
|---|---|---|
| Unit Testing | Test individual modules/functions | Test "calculateTotal()" function alone |
| System Testing | Test complete integrated system | Test full library borrowing workflow |
| Acceptance Testing | User validates system meets needs | Librarian tests before going live |
๐น Test Data Types (EXAM FAVORITE)
| Type | Example (marks 0-100) | Purpose |
|---|---|---|
| Normal Data ✅ | 50, 75, 90 |
Verify expected valid inputs work |
| Boundary Data ๐ฏ | 0, 100 |
Test edge limits of valid range |
| Invalid Data ❌ | -10, 150, "abc" |
Check error handling & validation |
๐น Input Validation Techniques
๐ Range Check:
0 ≤ marks ≤ 100
✉️ Format Check: email@domain.com
๐ข Type Check: isNumeric(phone)
✅ Presence Check: name != empty
๐ Length Check: password ≥ 8 chars
๐ 7.10 Implementation Methods
๐น When to Use Each Method
| Method | Best For | Pros | Cons |
|---|---|---|---|
| Direct (Big Bang) |
Small, low-risk systems | • Fast • Low cost |
• High risk • No fallback |
| Parallel | Critical systems (Banks, Hospitals) | • Safe • Easy rollback |
• Expensive • Double work |
| Pilot | Large organizations (Test in one branch) | • Low risk • Real-world feedback |
• Slow rollout • Branch comparison issues |
| Phased (Modular) |
Complex modular systems | • Manageable • Early benefits |
• Integration challenges • Longer timeline |
๐ฏ Exam Answer Template:
"For a banking system, I would recommend Parallel Implementation because:
✓ Critical data must not be lost
✓ Old system can run as backup
✓ Users can be trained gradually
✓ Errors can be fixed without stopping service"
"For a banking system, I would recommend Parallel Implementation because:
✓ Critical data must not be lost
✓ Old system can run as backup
✓ Users can be trained gradually
✓ Errors can be fixed without stopping service"
๐ Pass Paper Questions & Model Answers
๐น Question 1 (2 Marks)
Define SDLC.
✅ Model Answer:
SDLC (System Development Life Cycle) is a structured, phased process used to plan, create, test, deploy, and maintain information systems through stages such as planning, analysis, design, development, testing, implementation, and maintenance.
SDLC (System Development Life Cycle) is a structured, phased process used to plan, create, test, deploy, and maintain information systems through stages such as planning, analysis, design, development, testing, implementation, and maintenance.
๐น Question 2 (4 Marks)
List 4 phases of SDLC.
✅ Model Answer:
Planning Analysis Design Implementation
Planning Analysis Design Implementation
๐น Question 3 (2 Marks)
What is a feasibility study?
✅ Model Answer:
A feasibility study is the process of evaluating whether a proposed system is practical, affordable, technically achievable, and worth developing before committing resources to the project.
A feasibility study is the process of evaluating whether a proposed system is practical, affordable, technically achievable, and worth developing before committing resources to the project.
๐น Question 4 (6 Marks) – Context Diagram
Draw a context diagram for a Library Management System.
✅ Model Answer Structure:
- Center:
[ Library Management System ] - External Entities: Member Librarian Supplier
- Data Flows:
- Member → Book Request → System
- System → Borrow Confirmation → Member
- Librarian → Update Catalog → System
- System → Overdue Report → Librarian
๐น Question 5 (2 Marks)
State two programming control structures.
✅ Model Answer:
Selection (IF-ELSE) Iteration (FOR/WHILE loops)
Selection (IF-ELSE) Iteration (FOR/WHILE loops)
๐ Beginner-Friendly Quick Review
๐น Super Simple Summary Table
| Term | Super Simple Meaning | Memory Trick |
|---|---|---|
| SDLC | Build → Test → Use → Maintain | ๐ 4-step cycle |
| DFD | How data moves | ➜ Arrow diagram |
| Algorithm | Step-by-step problem solver | ๐ Recipe |
| Flowchart | Picture of an algorithm | ๐ผ️ Visual steps |
| Testing | Finding bugs before launch | ๐ Check first |
| Debugging | Fixing bugs after testing | ๐ง Repair mode |
| Direct Changeover | Switch old→new in one day | ⚡ Fast but risky |
| Parallel | Run old+new together | ๐ก️ Safe but costly |
๐น Exam Keyword → Answer Trick
| ๐ Question Keyword | ✅ Write This |
|---|---|
| "daily transactions", "billing", "ATM" | TPS |
| "reports", "summary", "analysis" | MIS |
| "decision", "strategy", "future plan" | DSS |
| "step by step", "cannot go back" | Waterfall |
| "flexible", "user feedback", "changing" | Agile |
| "fast", "prototype", "ready-made" | RAD |
๐ง FINAL MASTER TIP
๐ For DFD Questions:
✓ Draw neatly with pencil & ruler
✓ Label EVERY arrow with data name
✓ Use correct symbols ONLY
✓ Keep system as ONE process box
๐ For Algorithm Questions:
✓ Start with INPUT, end with STOP
✓ Use numbered steps
✓ Test your logic with sample values!
๐ For DFD Questions:
✓ Draw neatly with pencil & ruler
✓ Label EVERY arrow with data name
✓ Use correct symbols ONLY
✓ Keep system as ONE process box
๐ For Algorithm Questions:
✓ Start with INPUT, end with STOP
✓ Use numbered steps
✓ Test your logic with sample values!
