Overview of GCSE Computer Science Paper 1

May 7, 2025

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OCR GCSE Computer Science Paper 1 Overview

CPU and its Components

  • CPU (Central Processing Unit): Executes program instructions using data.
  • Components within CPU:
    • ALU (Arithmetic Logic Unit): Performs arithmetic and logic operations.
    • Control Unit: Coordinates the fetch-execute cycle and decodes instructions.
    • Cache: Small, fast memory storing frequently accessed instructions/data.
    • Registers: Ultra-fast storage for intermediate data; key registers include:
      • Memory Address Register (MAR): Holds memory location of data/instruction.
      • Memory Data Register (MDR): Holds the data/instruction itself.
      • Program Counter: Keeps track of the next memory address of instruction.
      • Accumulator: Stores results of operations.
  • Von Neumann Architecture: Defines CPU structure and fetch-execute cycle.

Fetch-Execute Cycle

  1. Fetch: Retrieve instruction from memory.
  2. Decode: Interpret the instruction.
  3. Execute: Perform the operation.

CPU Performance Factors

  • Clock Speed: Higher speeds mean more cycles per second.
  • Number of Cores: More cores can mean parallel processing if software allows.
  • Cache Size: Larger cache reduces reliance on slower RAM.

Embedded Systems

  • Simple, single-purpose computers within other devices (e.g., appliances, cars).

Storage Types

  • Primary Storage: RAM (volatile) and ROM (non-volatile; holds boot-up instructions).
  • Secondary Storage: Non-volatile storage for long-term data (HDDs, SSDs, etc.).
  • Virtual Memory: Extension of RAM using secondary storage.

Storage Types Comparison

  • Magnetic: Reliable, large capacity, but not durable.
  • Optical: Portable but less durable, small capacity.
  • Solid State: Fast, durable, but expensive.

Data Representation

  • Binary Units: Bits, nibbles, bytes, KB, MB, etc.
  • Binary to Decimal/Hexadecimal Conversion: Use place value tables.
  • Binary Addition & Shifts: Addition rules & doubling/halving with shifts.
  • Overflow Errors: Occur when storage limits are exceeded.

Character Sets

  • ASCII: Uses 8 bits, limited characters.
  • Unicode: Uses 16+ bits, supports multiple languages.

Images and Sound

  • Pixels: Basic unit of images; resolution determined by pixel count.
  • Color Depth: Bits per pixel determining color variety.
  • Sound: Sampled at intervals; quality determined by sample rate and bit depth.
  • Compression: Reduces file size;
    • Lossy: Reduces quality.
    • Lossless: Retains original data.

Networks

  • LAN and WAN: Local vs. wide area networks.
  • Client-Server vs. Peer-to-Peer: Centralized vs. decentralized communication.
  • Topologies: Star (central node) vs. Mesh (interconnected).

Internet and Protocols

  • IP Addresses: Identify device location.
  • Domain Name System (DNS): Translates domain names to IP.
  • Cloud: Online storage and computing services.
  • Protocols: TCP/IP, email protocols (POP, IMAP, SMTP).

Cybersecurity

  • Types of Attacks: SQL Injection, Brute Force, DDoS, Social Engineering.
  • Protection Methods: Firewall, encryption, physical security, anti-malware.

Operating Systems

  • Functions: User interface, memory management, task scheduling, peripheral management.
  • Utility Software: System support, e.g., defragmentation, encryption.

Legal and Ethical Issues

  • Legislation: Data Protection Act, Computer Misuse Act, Copyright laws.
  • Open Source vs. Proprietary Software: Licensing, availability of source code.
  • Privacy & Ethical Issues: Data minimization, balancing security with privacy.

Exam Tips

  • Focus on key points, balanced answers, context-specific responses.

These notes provide a comprehensive summary of key concepts for OCR GCSE Computer Science Paper 1, which includes understanding CPU components, data representation, networks, cybersecurity, and legal considerations.

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