IB Computer Science SL Topics

The standard-level topics in the International Baccalaureate Diploma Programme (IB) for Computer Science are Topics 1-4.

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Learning Aim:

In this topic, you will begin to understand computer and processor architectures as well as how computers represent data (binary, hexadecimal) and use logic to make decisions

What the syllabus says you need to know for this unit

 Computer Architecture and the Central Processing Unit (CPU)

• CPU Structure: The CPU is the ‘brain’ of the computer, responsible for interpreting and executing instructions. It consists of several key components:
  • Arithmetic Logic Unit (ALU): Performs all arithmetic operations (such as addition and subtraction) and logical operations (such as AND, OR, NOT).
  • Control Unit (CU): Manages the flow of data and instructions within the CPU, loading and decoding commands, and directing the operation of the ALU.
  • Registers: Small, fast storage locations within the CPU used to temporarily hold data and instructions during processing.
• Von Neumann Architecture: Most modern computers are based on the Von Neumann model, which separates the system into a processor module (for calculations) and a memory module (for storing data and instructions).

2. Memory and Storage

• Primary Memory:
  • RAM (Random Access Memory): Volatile memory used for the temporary storage of data and instructions that are actively being used by the CPU.
  • ROM (Read-Only Memory): Non-volatile memory containing permanent instructions, such as the system’s firmware.
• Cache Memory: A small, high-speed memory located close to the CPU, used to store frequently accessed data and instructions to speed up processing.
• Persistent Storage:
  • Needed to retain data when the computer is powered off.
  • Examples include hard drives, SSDs, and other forms of secondary storage.

3. Operating Systems and Software

• Operating System (OS) Functions:
  • Manages hardware resources and provides services for application software.
  • Handles input/output operations, peripheral management (e.g., keyboard, mouse, printer), multitasking, and system security.
  • Uses device drivers to communicate with hardware components.
• Application Software:
  • Programmes designed for end-users, such as word processors, web browsers, and spreadsheets.
  • Application software relies on the operating system to access hardware and system resources.

4. Data Representation

• Binary:
  • The fundamental language of computers, using only two digits: 0 and 1.
  • Each binary digit is called a bit; eight bits make a byte.
• Hexadecimal:
  • Base-16 number system, using digits 0–9 and letters A–F.
  • Used as a more human-friendly representation of binary values, as each hexadecimal digit corresponds to four binary digits (a nibble).
  • Example: The binary number 0100 1111 0101 is grouped into nibbles and converted into hexadecimal as 4F5.
• Other Terms:
  • Denary/Decimal: The base-10 number system, familiar in everyday use.

5. Logic and Decision Making

• Boolean Operators:
  • AND, OR, NOT, NAND, NOR, XOR.
  • Used to create logical expressions and circuits that form the basis of decision-making in computers.
• Truth Tables:
  • Tables used to show all possible input combinations and their corresponding outputs for logical operators.
• Logic Diagrams:
  • Visual representations of logical operations using standard symbols for each gate (AND, OR, NOT, etc.).
  • Used in the design and analysis of digital circuits.

Summary Table

Component/Concept	Description
CPU	Executes instructions; consists of ALU, CU, and registers
ALU	Performs arithmetic and logic operations
CU	Manages instruction execution and data flow
Registers	Temporary storage within the CPU
RAM	Volatile memory for active data
ROM	Non-volatile memory for permanent instructions
Cache	Fast memory for frequently used data
Persistent Storage	Retains data when powered off
Operating System	Manages hardware and software resources
Application Software	Programmes for end-users
Binary	Base-2 data representation
Hexadecimal	Base-16 data representation, more readable for humans
Boolean Logic	Logical operations and decision-making
Truth Tables	Show outputs for all logic input combinations
Logic Diagrams	Visual representation of logical circuits

1. Types of Networks

• LAN (Local Area Network): Connects computers within a limited area, such as a school or office.
• WAN (Wide Area Network): Spans large geographical areas, connecting multiple LANs (e.g., the Internet).
• WLAN (Wireless LAN): A LAN that uses wireless communication.
• VLAN (Virtual LAN): Groups devices from different physical LANs into a single logical network.
• SAN (Storage Area Network): Specialises in connecting storage devices.
• PAN (Personal Area Network): Covers a very small area, typically for personal devices (e.g., Bluetooth).
• VPN (Virtual Private Network): Creates a secure, encrypted connection over a public network.
• Extranet: Allows controlled access to outsiders.
• P2P (Peer-to-Peer): All computers act as both clients and servers.

Servers and Clients

• Server: Provides resources or services to other computers (clients) on the network.
• Client: Requests and uses resources provided by servers.

Key Hardware Components

• Hub: Connects devices in a network, sending data to all connected devices.
• Switch: Connects devices but sends data only to the intended recipient, reducing traffic.
• Router: Connects different networks and directs data between them.

2. Network Standards and Architecture

• Importance of Standards: Standards ensure compatibility and interoperability between devices and systems from different manufacturers. They define protocols, data formats, and electrical characteristics.
• Layered Architecture:
  • Networks are structured in layers (e.g., the OSI model), each with specific responsibilities, facilitating troubleshooting and development.

3. Data Transmission

• Protocols: Agreed rules for data communication (e.g., TCP, IP). They define how data is formatted, transmitted, and received.
• Data Packets: Data is broken into small units called packets for transmission.
• Packet Switching: Each packet may take a different route to its destination, where packets are reassembled. This method is efficient and robust, allowing multiple communications to share the same network resources.
• Transmission Media: Includes copper cables, fibre optics, and wireless signals, each with its own characteristics regarding speed, cost, and reliability.
• Serial vs. Parallel Transmission: Serial sends data one bit at a time; parallel sends multiple bits simultaneously.

4. Factors Affecting Data Transmission

• Speed Variations: Influenced by bandwidth, network congestion, hardware limitations, and environmental factors.
• Data Compression: Reduces file size for faster transmission and efficient use of bandwidth.

5. Wireless Networking

• Advantages: Flexibility, ease of installation, and mobility.
• Disadvantages: Potentially lower speeds, interference, and security risks.
• Components: Wireless access points, network interface cards (NICs), and appropriate software.
• Characteristics: Coverage area, signal strength, and susceptibility to interference.

6. Network Security

• Security Methods:
  • Encryption: Scrambles data to prevent unauthorised access.
  • Firewalls: Block unauthorised traffic.
  • MAC Address Filtering: Restricts network access to specific devices.
  • User Authentication: Requires usernames and passwords.
• Evaluation: Each method has strengths and weaknesses; combining them improves security.

7. Virtual Private Networks (VPNs)

• Technologies Required: Encryption, tunnelling protocols, authentication mechanisms.
• Advantages: Secure remote access, privacy, and protection on public networks.
• Disadvantages: Potentially slower speeds, complexity, and reliance on correct configuration

Revision

Quiz yourself (Quizlet) or study more topic 3 Quizlet Terms.