🏢 G.C.E. A/L ICT Chapter 07: Information Systems
Complete Revision Package | Systems, SDLC, Security & Types of IS
What is a System?
Definition: A collection of interrelated components working together to achieve a common objective.
Characteristics: Organization, Interaction, Interdependence, Integration, and Goal-Oriented.
5 Components: Input → Processing → Output → Feedback → Control.
Data vs. Information vs. Knowledge
| Concept | Definition | Example |
|---|---|---|
| Data | Raw, unprocessed facts | 75, 80, 90, "Amal" |
| Information | Processed, meaningful data | Amal's average mark = 82% |
| Knowledge | Info + experience for decisions | Stocking umbrellas before monsoon based on past sales data. |
Types of Systems
- Physical: Contains physical objects (Computer, School).
- Abstract: Concepts or ideas (Mathematical formula, Business plan).
- Open: Interacts with external environment (Bank, Hospital).
- Closed: Little/no external interaction (Mechanical watch).
- Natural: Created by nature (Solar system, Human body).
- Artificial: Created by humans (Banking system, IS).
6 Components of an Information System
- Hardware: Physical devices (CPU, Keyboard, Scanner, Server).
- Software: Programs (System Software like OS, Application Software like Payroll).
- Data: Raw input (Numeric, Text, Multimedia, Date/Time).
- People: End users, System Analysts, Programmers, DBAs, Network Admins.
- Procedures: Rules/instructions for using the system correctly.
- Networks: Connected devices for data sharing (LAN, Internet, Wi-Fi).
Information Processing Cycle
Input: Collecting/entering data.
Processing: Transforming data (Classification, Sorting, Calculation, Summarizing).
Output: Producing meaningful information (Reports, Charts, Bills).
Storage: Saving data for future use (Database, Cloud).
Feedback: Information returned to improve system performance.
Characteristics of Good Information
Accuracy: Correct and error-free. | Relevance: Useful for the purpose.
Timeliness: Available when needed. | Completeness: Contains all required details.
Reliability: From trustworthy sources. | Security: Protected from unauthorized access.
Management Pyramid Systems
| System | Users | Purpose | Example |
|---|---|---|---|
| TPS | Operational Staff | Process daily transactions | ATM, POS, Airline Booking |
| MIS | Middle Managers | Generate summarized reports | Monthly Sales Report |
| DSS | Managers/Analysts | Support semi-structured decisions ("What-if" analysis) | Loan Approval System |
| EIS | Senior Executives | Strategic, long-term planning | Business Dashboard |
Expert Systems (ES) & Office Automation (OAS)
Expert System: AI-based system imitating human expert decision-making. Components: Knowledge Base, Inference Engine, User Interface. (e.g., Medical Diagnosis).
Office Automation System (OAS): Technology to improve office productivity (e.g., Word Processors, Spreadsheets, Email, Video Conferencing).
System Development Life Cycle (SDLC)
Stages: 1. Planning → 2. Feasibility Study → 3. Requirement Analysis → 4. System Design → 5. Development → 6. Testing → 7. Implementation → 8. Maintenance.
Feasibility Types: Technical, Economic, Operational, Schedule, Legal.
Requirements: Functional (what it does) vs. Non-functional (how well it does it: speed, security).
System Analyst & Fact Finding
System Analyst: Analyzes problems, gathers requirements, and designs IS solutions.
Fact-Finding Techniques: Interviews, Questionnaires, Observation, Document Review, Sampling.
DFD & Database Basics
DFD Components: External Entity, Process, Data Flow, Data Store. (Context Diagram shows the whole system as one process).
Database: Entity (real-world object), Attribute (property), Primary Key (unique identifier), Foreign Key (links to another table's primary key).
Normalization: Organizing data to reduce redundancy (1NF, 2NF, 3NF).
System Testing Levels
- Unit Testing: Testing individual modules separately (by developers).
- Integration Testing: Testing combined modules to ensure they work together.
- System Testing: Testing the complete integrated system as a whole.
- User Acceptance Testing (UAT): Testing by actual end-users to confirm it meets requirements.
Methods: Black Box (tests functionality, no code knowledge) vs. White Box (tests internal logic/code). Alpha (internal) vs. Beta (external users).
System Conversion Methods
| Method | Description | Risk / Cost |
|---|---|---|
| Direct | Old stops, new starts immediately. | High Risk / Low Cost |
| Parallel | Old and new run together for a period. | Low Risk / High Cost |
| Pilot | New system introduced to one small group/department first. | Medium Risk / Medium Cost |
| Phased | New system introduced gradually in stages/modules. | Low Risk / Medium Cost |
System Maintenance Types
- Corrective: Fixes errors/bugs found after implementation.
- Adaptive: Modifies system for a changed environment (e.g., new OS, new laws).
- Perfective: Improves performance or adds new features.
- Preventive: Makes changes to prevent future problems (e.g., security patches).
The CIA Triad
- Confidentiality: Data accessed only by authorized users (Methods: Passwords, Encryption, Access Control).
- Integrity: Data remains accurate and unchanged by unauthorized persons (Methods: Digital signatures, Hashing).
- Availability: Systems/data available when required (Methods: Backups, Disaster Recovery, Maintenance).
Security Threats & Protection
Threats: Malware (Virus, Worm, Trojan, Spyware, Ransomware), Phishing, Social Engineering, Brute Force Attacks.
Protection Methods:
- Authentication: Something you know (Password), have (Smart card), or are (Fingerprint). MFA uses 2+ methods.
- Encryption: Converting Plain Text to Cipher Text (Symmetric = 1 key, Asymmetric = Public/Private keys).
- Firewall: Monitors and controls incoming/outgoing network traffic.
- Backup: Full, Incremental, or Differential copies of data.
Ethical Issues
- Privacy: Right to control personal information.
- Intellectual Property: Legal protection for creations (Software, Music).
- Software Piracy: Illegal copying/use of paid software.
- Cybercrime: Illegal activity using computers (Hacking, Identity theft).
📌 Top A/L ICT Chapter 07 Focus Areas
🔄 TPS vs MIS vs DSS vs EIS: Know the users, purpose, and data type for each.
📝 SDLC Stages: Memorize the 8 stages in order and the types of feasibility.
🔍 System Analyst: Responsibilities and fact-finding techniques.
🗺️ DFD & ERD: Symbols, Primary/Foreign Keys, and Normalization (1NF, 2NF, 3NF).
✅ Validation vs Verification: Validation = reasonable/acceptable. Verification = matches original source.
🔄 Conversion Methods: Direct, Parallel, Pilot, Phased (know risk/cost trade-offs).
🛡️ Security: CIA Triad, Encryption types, and Malware differences (Virus vs Worm).
📝 Quick Essay Question Frameworks
Q: Explain different types of Information Systems.
A: Define TPS (daily transactions, operational), MIS (summarized reports, middle management), DSS ("what-if" analysis, analytical decisions), and EIS (strategic planning, executives). Give one example for each.
Q: Explain methods to protect an information system.
A: Discuss Authentication (MFA), Access Control, Encryption (Symmetric/Asymmetric), Firewalls, Antivirus, Backups, and Disaster Recovery Planning.
