📘 GCE A/L ICT – UNIT 7
🔷 7.1 INTRODUCTION TO SYSTEM DEVELOPMENT
🔹 What is a System?
📌 Example: School Management System
| Component | Description |
|---|---|
| Inputs | Student data, attendance, marks |
| Processes | Attendance tracking, marks calculation, report generation |
| Outputs | Reports, results, certificates |
🔹 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 |
🔹 What is System Development?
The process of creating or modifying a system to meet user requirements and solve problems.
🔷 7.2 SYSTEM DEVELOPMENT LIFE CYCLE (SDLC)
🔹 Definition
🔹 The 7 Phases of SDLC
-
Planning
• Identify the problem/need
• Conduct feasibility study
• Define project scope & resources -
Analysis
• Study current system
• Gather user requirements
• Create Requirement Specification Document (RSD) -
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
🔹 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 |
🔹 SDLC Deliverables (Exam Important)
| Phase | Key Deliverables |
|---|---|
| Analysis | • Requirement Specification Doc • DFDs (Level 0, 1) • Use Case Diagrams |
| Design | • ER Diagrams • Database Schema • UI Design Mockups • System Architecture |
🔷 7.3 FEASIBILITY STUDY
🔹 Purpose
Feasibility study evaluates if the project is practical, affordable, and achievable.
🔹 Types of Feasibility (TEOS)
| Type | Key Question | Example |
|---|---|---|
| Technical 🔧 | Do we have the technology & skills? | Need mobile app developers, cloud server |
| Economic 💰 | Do benefits > costs? | Cost: Rs.500k | Benefit: Rs.1M → ✅ Feasible |
| Operational 👥 | Will users accept & use it? | Can teachers learn the new system easily? |
| Schedule 📅 | Can it be done on time? | Can we finish before next academic year? |
🔹 Economic Feasibility Formula (Concept)
Expected Benefits > Development + Operational Costs
Example Calculation:
- 💸 Development Cost: Rs. 500,000
- 📈 Annual Benefit: Rs. 300,000 × 4 years = Rs. 1,200,000
- ✅ Net Gain: Rs. 700,000 → Project is feasible!
🔹 Real-World Example: School Mobile App
🔷 7.4-7.5 DATA FLOW DIAGRAMS (DFD)
🔹 What is a DFD?
🔹 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 |
🔹 Levels of DFD
- 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
🔷 🔹 Context Diagram (Level 0 DFD) – EXAM CRITICAL
- The whole system as a single process
- All external entities interacting with it
- Data flows between entities and system
🔹 Why Context Diagrams Matter
- ✓ Clear system overview for stakeholders
- ✓ Defines system boundaries (what's in/out)
- ✓ Identifies all users & external systems
- ✓ Clarifies inputs & outputs early
- ✓ Improves developer-client communication
🔹 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] [System] → Confirmation → [Student]
🔹 Full Text-Based Example
🔹 Critical Rules (MCQ Gold)
- 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
- Drawing multiple process circles ❌
- Adding database symbols ❌
- Unlabeled arrows ❌
- Missing key entities (e.g., forgot "Bank") ❌
🔷 7.6 ALGORITHMS
🔹 Definition
🔹 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 |
🔹 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)
🔹 Example: Find Largest of 3 Numbers (Exam Level)
🔹 Example: Check Pass/Fail
🔷 7.7 FLOWCHARTS
🔹 Definition
A flowchart is a graphical representation of an algorithm using standardized symbols to show the flow of control.
🔹 Essential Flowchart 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 |
🔹 Example: Check Even/Odd Number
🔹 Loop Structure Concept
For repetition (e.g., FOR or WHILE loops), draw an arrow returning to the decision diamond to show iteration.
🔷 7.8 PROGRAMMING CONCEPTS
🔹 Variables
Named storage locations that hold data values.
int age = 20;String name = "Yew";boolean isActive = true;
🔹 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 |
🔹 Operators
+ - * / %
⚖️ Comparison: == != > < >= <=
🔗 Logical: AND(&&), OR(||), NOT(!)
📝 Assignment: = += -=
🔹 Control Structures (CORE CONCEPT)
1️⃣ Sequence
Statements executed in order, one after another.
2️⃣ Selection (Decision)
Execute different code based on a condition.
IF marks >= 50 THEN
PRINT "PASS"
ELSE
PRINT "FAIL"
END IF
3️⃣ Iteration (Loop)
Repeat a block of code multiple times.
FOR i = 1 TO 10 STEP 1
PRINT i
NEXT i
🔷 7.9 TESTING & DEBUGGING
🔹 Testing vs Debugging
| Testing | Debugging |
|---|---|
| • Finding errors/bugs • Done BEFORE release • Uses test data |
• Fixing identified errors • Done AFTER testing • Requires code analysis |
🔹 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 |
🔹 Test Data Types (EXAM FAVORITE)
| Type | Example (for marks 0-100) | Purpose |
|---|---|---|
| Normal Data ✅ | 50, 75, 90 |
Verify expected valid inputs work |
| Boundary Data 🎯 | 0, 100 |
Test edge limits of valid range |
| Invalid Data ❌ | -10, 150, "abc" |
Check error handling & validation |
🔹 Input Validation Techniques
0 ≤ marks ≤ 100
✉️ Format Check: email@domain.com
🔢 Type Check: isNumeric(phone)
✅ Presence Check: name != empty
🔐 Length Check: password ≥ 8 chars
🔷 7.10 IMPLEMENTATION METHODS
🔹 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 |
"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"
📄 PASS PAPER QUESTIONS & MODEL ANSWERS
🔹 Question 1 (2 Marks)
Define SDLC.
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.
🔹 Question 2 (4 Marks)
List 4 phases of SDLC.
Planning Analysis Design Implementation
(Also accept: Development, Testing, Maintenance)
🔹 Question 3 (2 Marks)
What is a feasibility study?
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.
🔹 Question 4 (2 Marks)
Name two types of feasibility.
Technical Feasibility Economic Feasibility
(Also accept: Operational, Schedule)
🔹 Question 5 (2 Marks)
What is an algorithm?
An algorithm is a finite, step-by-step procedure written in clear, unambiguous language to solve a specific problem or perform a task.
🔹 Question 6 (6 Marks)
Draw a flowchart to find the largest of two numbers.
- Start (Oval)
- Input A, B (Parallelogram)
- Decision: A > B? (Diamond)
- Yes branch → Print A (Rectangle)
- No branch → Print B (Rectangle)
- End (Oval)
🔹 Question 7 (2 Marks)
What is a DFD?
A Data Flow Diagram (DFD) is a graphical representation that shows how data moves through a system, including processes, data stores, external entities, and the flows between them.
🔹 Question 8 (2 Marks)
State two programming control structures.
Selection (IF-ELSE) Iteration (FOR/WHILE loops)
(Also accept: Sequence)
🔹 Question 9 (2 Marks)
What is debugging?
Debugging is the process of identifying, analyzing, and correcting errors (bugs) in a program's code to ensure it functions as intended.
🔹 Question 10 (6 Marks) – Context Diagram
Draw a context diagram for a Library Management System.
- 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
- Supplier → New Books List → System
👉 For DFD/Context Diagram Questions:
✓ Draw neatly with pencil & ruler
✓ Label EVERY arrow with data name
✓ Use correct symbols ONLY (no databases in Level 0!)
✓ Show ALL external entities mentioned in question
✓ Keep system as ONE process box
👉 For Algorithm/Flowchart Questions:
✓ Start with INPUT, end with STOP
✓ Use numbered steps for algorithms
✓ Label decision branches "Yes/No" in flowcharts
✓ Test your logic with sample values!
✨ Practice drawing 3 different context diagrams before exam day! ✨
🌟 UNIT 7 – SUPER SIMPLE EXPLANATIONS
👉 Perfect if you're learning this for the FIRST time!
🌟 1. What is an Information System?
An Information System is a system that:
- 📥 Collects data (Input)
- ⚙️ Processes data (Process)
- 💾 Stores data (Storage)
- 📤 Outputs information (Output)
💡 The Golden Rule: Input → Process → Output
📌 Real-Life Example: Student Result System
| Stage | What Happens | Example |
|---|---|---|
| 📥 Input | User enters data | Teacher types marks: 75, 80, 90 |
| ⚙️ Process | System calculates/works | System adds marks & divides by 3 |
| 📤 Output | System shows result | Displays: "Average = 81.67 – Grade: A" |
🌟 2. Types of Systems – Very Easy!
Think of a school or business — different people need different systems.
🟢 OAS – Office Automation System
💡 Purpose: Helps with documents & communication
🎯 Easy Memory:
OAS = Office work tools
Examples:
Real-life: School office typing student admission letters
🟢 TPS – Transaction Processing System
💡 Purpose: Handles daily small events (transactions)
🎯 Easy Memory:
TPS = Daily work system
What is a transaction? A small event like buying, paying, withdrawing
Examples:
Real-life: You buy a biscuit → system records sale → updates stock
🟢 MIS – Management Information System
💡 Purpose: Takes TPS data & makes reports for decisions
🎯 Easy Memory:
MIS = Reports for managers
Examples:
Real-life: Principal checks "Which subject has lowest pass rate?"
🟢 DSS – Decision Support System
💡 Purpose: Helps make big strategic decisions
🎯 Easy Memory:
DSS = Smart decision helper
Examples:
Real-life: CEO uses sales trends + market data to decide expansion
📊 Quick Comparison Table (MEMORIZE!)
| System | Used By | Purpose | Keyword |
|---|---|---|---|
| OAS | Office staff | Documents & communication | 📝 Office work |
| TPS | Front-line staff | Daily transactions | 💰 Daily events |
| MIS | Managers | Reports from TPS data | 📊 Reports |
| DSS | Top managers | Big decisions | 🎯 Strategy |
🌟 3. System Development Models (How Systems Are Built)
👉 Different ways to build a system — like different recipes for cooking!
🟡 Waterfall Model – Step by Step
🎯 Easy Memory:
Waterfall = Straight line
Steps (Must Know Order!):
- Requirements – What does the user want?
- Design – Plan how it will look & work
- Coding – Write the actual program
- Testing – Find & fix bugs
- Deployment – Launch for real use
✅ Best for: Small projects with clear, fixed requirements
🟡 Spiral Model – Loop with Risk Check
🎯 Easy Memory:
Spiral = Circle + checking risks
How it works:
- 🔄 Plan → Design → Build → Evaluate → Repeat
- ⚠️ Each loop checks: "What could go wrong?"
🟡 Agile Model – Flexible & Fast
🎯 Easy Memory:
Agile = Flexible & fast
How it works:
- 🧩 Break project into small "sprints" (2-4 weeks each)
- 👥 Show working part to user → get feedback → improve
- 🔁 Repeat until complete
🟡 RAD – Rapid Application Development
🎯 Easy Memory:
RAD = Fast development
How it works:
- 🧰 Use pre-built components & templates
- ⚡ Create quick prototypes → test → refine
- 👥 Involve users heavily from start
📊 Model Comparison (Exam Favorite!)
| Model | Key Idea | Best For | Keyword |
|---|---|---|---|
| Waterfall | Step-by-step, no going back | Small, clear projects | 🪜 Straight line |
| Spiral | Loop + risk checking | Large, risky projects | 🌀 Circle + risk |
| Agile | Small parts + user feedback | Changing requirements | 🤸 Flexible |
| RAD | Fast build with tools | Tight deadlines | ⚡ Speed |
🌟 4. Tools Used in System Development
🔵 DFD – Data Flow Diagram
🎯 Easy Memory:
DFD = Data movement diagram
💡 Example: Student Registration
🔑 3 Basic Symbols (Context Diagram Level):
| Symbol | Name | Meaning |
|---|---|---|
| ▭ Rectangle | External Entity | Person/organization outside system |
| ○ Circle | Process | Something that transforms data |
| ➜ Arrow | Data Flow | Direction data moves |
🔵 ER Diagram – Database Design
🎯 Easy Memory:
ER = Data relationships
💡 Example: Student & Course
🔑 3 Key Parts:
| Part | Meaning | Example |
|---|---|---|
| Entity | Object/thing we store data about | Student, Course, Teacher |
| Attribute | Details about an entity | name, ID, email, phone |
| Relationship | How entities connect | Student enrolls in Course |
🔵 Process Description
🎯 Easy Memory:
Process description = step explanation
Two Common Methods:
| Method | What It Is | Example |
|---|---|---|
| Flowchart | Graphical steps with symbols | Diamond for decision, rectangle for action |
| Structured English | Simple English steps (like algorithm) | 1. Input marks 2. If marks≥50 → Pass |
🌟 5. SDLC – Super Simple 4-Step View
👉 Forget complex phases — just remember these 4 big steps:
🟣 Step 1: DESIGN – Plan It
Key Tasks:
- 📝 Design input forms (What data will users enter?)
- 📊 Design output reports (What will system show?)
- 🗄️ Design database (How to store data?)
- 🎨 Design user interface (What will screens look like?)
🟣 Step 2: TESTING – Check It
Two Main Types:
| Type | What It Tests | Example |
|---|---|---|
| Unit Testing | One small part/function | Test "calculateAverage()" alone |
| System Testing | Whole system together | Test full registration → result → report flow |
🟣 Step 3: DEPLOYMENT – Launch It
4 Deployment Methods (Know These!):
| Method | Simple Explanation | Best For |
|---|---|---|
| Direct | Switch off old → switch on new (one day) | Small, low-risk systems |
| Parallel | Run old + new together for a while | Critical systems (banks, hospitals) |
| Pilot | Test in ONE place first (e.g., one branch) | Large organizations |
| Phased | Launch module by module (e.g., registration first, then results) | Complex systems |
🟣 Step 4: MAINTENANCE – Fix & Improve
Two Main Types:
🌟 SUPER SIMPLE SUMMARY – MUST REMEMBER 💯
| Term | Super Simple Meaning | Memory Trick |
|---|---|---|
| OAS | Office work tools | 📝 Office = OAS |
| TPS | Daily transactions | 💰 Transaction = TPS |
| MIS | Reports for managers | 📊 Manager = MIS |
| DSS | Big decision helper | 🎯 Decision = DSS |
| Waterfall | Step-by-step, no going back | 🪜 Stairs |
| Agile | Flexible, small parts | 🤸 Jump & change |
| RAD | Build very fast | ⚡ Lightning |
| Spiral | Loop + check risks | 🌀 Spiral + ⚠️ |
| DFD | How data moves | ➜ Arrow diagram |
| ERD | How data connects | 🔗 Relationship map |
| SDLC | Build → Test → Use → Maintain | 🔄 4-step cycle |
🎯 EXAM TRICKS – VERY IMPORTANT!
| 🔍 Question Keyword | ✅ Write This System | 💡 Why? |
|---|---|---|
| "daily transactions", "buying", "billing", "ATM" | TPS | TPS handles small daily events |
| "reports", "summary", "monthly analysis" | MIS | MIS makes reports from TPS data |
| "decision", "strategy", "should we...?", "future plan" | DSS | DSS helps with big decisions |
| "typing letters", "emails", "documents" | OAS | OAS is for office document work |
| "step by step", "cannot go back", "sequential" | Waterfall | Waterfall is linear, no iteration |
| "flexible", "user feedback", "changing requirements" | Agile | Agile adapts to changes |
| "fast", "prototype", "ready-made tools" | RAD | RAD focuses on speed |
| "risk", "large project", "check each phase" | Spiral | Spiral checks risks in loops |
If asked to draw a Context Diagram:
1️⃣ Draw ONE rectangle in center = [System Name]
2️⃣ Draw rectangles around it = External Entities
3️⃣ Draw arrows between them = Data Flows
4️⃣ LABEL EVERY ARROW!
5️⃣ NO circles, NO databases, NO internal processes!
✅ Beginner Section Complete!
📌 Tip: Review the "Super Simple Summary" table 3x before exam!
🔄 Next: Ask for 1-page revision sheet or model exam answers
📚 GCE A/L ICT – UNIT 7 COMPLETE NOTES
System Development • DFD • Algorithms • Programming • Exam Ready
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