Comprehensive Revision of SS1, 2 and 3 – SS3 Digital Technologies Lesson Note (Third Term)

This note revises the main areas of the Digital Technologies syllabus: computer hardware, software, networking, logic, algorithms and programming, and data security and ethics. Hardware is the physical part of a computer, software is the set of instructions that runs on it, and a network connects computers so that they share resources.

Behavioural objectives

By the end of the lesson, students should be able to:

• name the parts of the CPU and state the function of each;
• distinguish between RAM and a hard drive/SSD;
• distinguish between system software and application software, with examples;
• identify the types of network (PAN, LAN, WAN) and the three topologies;
• state the meaning of logic gates, algorithms, flowcharts and the two types of programming language;
• name common data security threats, the defences against them and basic rules of computer ethics.

What is computer hardware?

Everything in computing starts with the physical stuff you can touch.

• The CPU (Central Processing Unit): Often called the “Brain.” It has two main parts:
  1. ALU (Arithmetic Logic Unit): Does the math and logic (Is 5 > 3?).
  2. CU (Control Unit): The traffic warden that tells data where to go.
• Memory vs. Storage:
  1. RAM (Volatile): The computer’s “Short-term memory.” It disappears when the power goes out.
  2. Hard Drive/SSD (Non-volatile): The “Long-term memory.” It keeps your files safe even when the computer is off.

Revision tip: Remember that Input (Keyboard, Mouse, Scanner) goes in, Processing (CPU) happens, and Output (Monitor, Printer, Speakers) comes out.

What is software?

Hardware is useless without Software, the invisible instructions that tell it what to do. We divide software into two main families:

1. System Software: This is the “Foundation.” The most important one is the Operating System (OS) like Windows, Android, or macOS. Without an OS, the computer won’t even start. It also includes Utility Software like Antivirus or Disk Cleaners.
2. Application Software: These are the “Tools” we use to get work done.
   1. Word Processors (MS Word): for letters.
   2. Spreadsheets (MS Excel): for calculations.
   3. Database (MS Access): for organised records.
   4. Graphics (CorelDraw/Photoshop): for design.

What is a network?

A network is just two or more computers connected to share resources.

Types of network

• PAN (Personal): Your phone connected to your Bluetooth headphones.
• LAN (Local): Computers in your school lab or home.
• WAN (Wide): The Internet (the biggest WAN in the world).

Topologies (the shapes)

• Star: Everything connects to a central “Hub.” (Most common today).
• Bus: Everything connects to one single long cable.
• Ring: Each computer is connected to two others in a circle.

Protocols

Remember HTTP for websites and SMTP for emails. These are just the “rules” for how data travels.

What are logic, algorithms and programming?

This is the “Thinking” part of the syllabus. Computers don’t understand English; they understand Logic.

• Logic Gates: AND (needs both), OR (needs either), NOT (reverses it).
• Algorithms: A step-by-step plan to solve a problem.
• Flowcharts: The “Map” of an algorithm.
  1. Decision (Diamond): Used for “If” questions.
  2. Process (Rectangle): Used for calculations.

Programming languages

• Low-Level: Machine language (1s and 0s). It is hard for humans and easy for computers.
• High-Level: Python, BASIC, Java. It is easy for humans, but needs a Compiler or Interpreter to translate it for the computer.

How do we stay safe: data security and ethics

As we move into a digital world, we have to protect our “Digital Lives.”

Threats and defences

• The Threat: Viruses, Worms, and Trojans. These are pieces of code designed to steal or destroy data.
• The Defence:
  1. Antivirus: Scans and removes “bad” code.
  2. Firewall: Blocks unauthorised people from entering your network.
  3. Encryption: Scrambling your data so only the person with the “Key” can read it.

Computer ethics

• Don’t use computers to steal or harm others.
• Respect Copyright (don’t pirate software or music).
• Avoid Plagiarism (always give credit if you use someone else’s information).

How should students prepare for the exam?

To pass your exam, focus on definitions, functions (what does it do?), and comparisons (how is A different from B?).

Evaluation

1. Name the two main parts of the CPU and state what each does.
2. State two differences between RAM and a hard drive/SSD.
3. Give two examples each of system software and application software.
4. Describe the star, bus and ring topologies.
5. Name three ways of protecting data from threats such as viruses, worms and Trojans.

Assignment

1. Explain the difference between a low-level and a high-level programming language.
2. List three rules of computer ethics.