Storage Devices (Hard Drives, SSDs, USBs)

    OCR
    GCSE

    Secondary storage is the non-volatile medium required to retain data and programs when a computer system is powered off, addressing the volatility of primary memory (RAM). Candidates must distinguish between the three primary technologies—magnetic (HDD), optical (CD/DVD/Blu-ray), and solid-state (SSD/Flash)—based on their physical operating principles. Assessment demands a comparative analysis of these devices against six critical performance criteria: capacity, speed (read/write), portability, durability, reliability, and cost per gigabyte. Mastery involves justifying the selection of specific storage solutions for diverse real-world scenarios, from enterprise data centers to embedded systems.

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    Objectives
    3
    Exam Tips
    3
    Pitfalls
    4
    Key Terms
    4
    Mark Points

    What You Need to Demonstrate

    Key skills and knowledge for this topic

    • Award 1 mark for explicitly stating that secondary storage is non-volatile and required to retain data when the computer is powered off
    • Award 1 mark for justifying the choice of Solid State Drives (SSD) over Magnetic Hard Drives (HDD) by citing 'higher durability due to lack of moving parts'
    • Award 1 mark for showing the correct expression for image size calculation: width multiplied by height multiplied by colour depth
    • Award 1 mark for converting the final calculated file size from bits to bytes by dividing the total by 8

    Marking Points

    Key points examiners look for in your answers

    • Award 1 mark for explicitly stating that secondary storage is non-volatile and required to retain data when the computer is powered off
    • Award 1 mark for justifying the choice of Solid State Drives (SSD) over Magnetic Hard Drives (HDD) by citing 'higher durability due to lack of moving parts'
    • Award 1 mark for showing the correct expression for image size calculation: width multiplied by height multiplied by colour depth
    • Award 1 mark for converting the final calculated file size from bits to bytes by dividing the total by 8

    Examiner Tips

    Expert advice for maximising your marks

    • 💡When comparing storage media, always use comparative terms (e.g., 'faster access speed', 'more durable') rather than absolute terms like 'fast' or 'strong'
    • 💡Memorize the six key characteristics: Capacity, Speed, Portability, Durability, Reliability, and Cost; questions often ask to select the 'most suitable' device based on one specific characteristic
    • 💡For calculation questions, write out the full multiplication expression (e.g., 10 x 1000 x 1000) before solving; marks are often awarded for the correct logic even if the arithmetic fails

    Common Mistakes

    Pitfalls to avoid in your exam answers

    • Confusing 'memory' (RAM) with 'storage' (HDD/SSD); candidates often incorrectly state that adding more storage improves CPU processing speed
    • Failing to divide by 8 when converting from bits to bytes during file size calculations, resulting in an answer 8 times too large
    • Using vague adjectives like 'cheap' or 'fast' without making a relative comparison (e.g., 'cheaper per GB than SSD') or specifying the characteristic context

    Study Guide Available

    Comprehensive revision notes & examples

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    Key Terminology

    Essential terms to know

    Physical operating principles (Magnetic polarity, Optical pits/lands, Electron trapping)
    Comparative performance metrics (Capacity, Speed, Cost, Durability, Portability, Reliability)
    Scenario-based selection and justification of storage media
    Calculation of storage requirements and unit conversion

    Likely Command Words

    How questions on this topic are typically asked

    State
    Explain
    Calculate
    Compare
    Justify

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