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πŸ’» A – Computer System Fundamentals

πŸ“˜ Introduction​

This topic covers the basic structure and operation of computer systems. It explains how hardware components work together, how data is stored and processed, and the roles of different types of software. Understanding these fundamentals supports problem-solving and system design in later topics.

(Source: ICT C&A Guide, p.17)

🎯 Learning Objectives​

By the end of this topic, students should be able to:

  • Explain the functions of hardware within a computer system
  • Describe the structure and functions of a CPU and its components
  • Outline the steps in the fetch-decode-execute cycle
  • Describe the functions and characteristics of RAM, ROM, and cache memory
  • Select and justify appropriate input/output devices for a given context
  • Describe characteristics of storage devices (access method, volatility, capacity, speed)
  • Know the functions of system software, application software, and utility programs
  • State the functions and needs of utility and driver programs
  • Distinguish between modes of operation (e.g., batch, real-time, parallel)

(Source: ICT C&A Guide, pp.17–20)

πŸ”‘ Key Concepts​

βš™οΈ Basic Machine Organisation​

  • CPU (Central Processing Unit): Executes instructions; includes ALU, control unit, and registers
  • Fetch-Decode-Execute Cycle:
    1. Fetch instruction from memory
    2. Decode the instruction
    3. Execute the operation
  • Memory Types:
    • RAM: Volatile, temporary storage (e.g., running programs)
    • ROM: Non-volatile, stores firmware (e.g., BIOS)
    • Cache: High-speed memory close to CPU for frequently used data
  • Storage Devices:
    • Examples: HDD, SSD, USB flash, optical disc, magnetic tape
    • Characteristics: random vs. sequential access, volatile vs. non-volatile, capacity, transfer rate
  • Input/Output Devices:
    • Chosen based on data type (text, image, audio, video) and context
    • Justification required in exams (e.g., β€œUse a barcode scanner for fast, accurate input in supermarkets”)

πŸ“¦ System Software​

  • System Software: Manages hardware and provides platform for applications (e.g., Windows, macOS, Linux)
  • Application Software: Performs user tasks (e.g., Word, Excel, browser)
  • Utility Programs: Maintain system performance (e.g., antivirus, disk defragmenter, file compressor)
  • Driver Programs: Enable communication between OS and hardware devices

⏱️ Modes of Operation​

  • Batch Processing: Jobs collected and processed later (e.g., payroll)
  • Real-time Processing: Immediate response required (e.g., airbag system)
  • Parallel Processing: Multiple CPUs work simultaneously
  • Distributed Processing: Tasks shared across networked computers
  • Virtualisation: Running multiple OS environments on one machine