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Understanding Peripheral Storage Devices

Apr 29, 2025

Lesson on IGCSE ICT - Lesson 4: Peripheral Storage Devices

Introduction

  • Completion of Chapter 1 in IGCSE ICT
  • Recap of previous lessons:
    • Digital devices
    • Peripheral input devices
    • Physical output devices
  • Today's focus: Storage Devices
  • Practice questions at the end of the lesson.

Memory vs. Storage

  • Memory: Temporary data storage used by computers for tasks.
  • Storage: Permanent data storage, e.g., files saved on drives.
  • Example: Mobile phone uses memory for apps, storage for photos.

Types of Storage

  • Primary Memory: Used when a computer starts (booting OS, running programs).
  • Secondary Memory: Permanent, non-volatile (data persists after shutdown).

Uses of Secondary Memory

  • Stores data and applications permanently.
  • Acts as virtual memory.
  • Used for data backup.

Storage Devices vs. Storage Media

  • Storage Media: The material where data is stored.
  • Storage Devices: Tools that read/write data from/to storage media.
  • Examples:
    • Hard drive (storage device) contains magnetic disk (media).
    • USB drive (storage device) contains flash memory (media).

Units of Storage Capacity

  • Measured in bytes, denoted by 'B'.
  • Important units:
    • 1 KB = 1000 bytes
    • 1 MB = 1,000,000 bytes
    • 1 GB = 1,000,000,000 bytes

Data Access Speed

  • Measured in bytes per second (BPS).
  • Fast Devices: e.g., hard drives (MBPS).
  • Slow Devices: e.g., floppy disks (KBPS).

Types of Secondary Storage Devices

  1. Magnetic Storage Devices
    • Use magnetism on spinning disks.
    • Example: Hard Disk Drives (HDD), Magnetic Tapes.
  2. Optical Storage Devices
    • Use lasers to read/write data.
    • Example: CD, DVD, Blu-ray.
  3. Solid State Storage Devices
    • Use electronic circuits, no moving parts.
    • Example: USB Flash Drives, SSDs, Memory Cards.

Common Storage Types

  • Hard Disk Drive (HDD): Large capacity, fast data access.
  • Optical Media:
    • CD: Stores ~700 MB using laser.
    • DVD: Stores up to 8.5 GB using red laser.
    • Blu-ray: Stores up to 50 GB using violet laser.
  • Solid State Storage:
    • USB Sticks: Portable, fast read/write.
    • Memory Cards: Used in cameras and phones.
    • Smart Cards: Used in credit cards with chips.

Comparison of Storage Types

  • Speed: Flash media fastest, magnetic tape slowest.
  • Capacity: HDDs have large capacity, optical media varies.
  • Portability: Flash media portable, HDDs less so.

Practice Questions

  1. Uses of Secondary Storage: Data storage, application storage, backup, virtual memory.
  2. Types of Secondary Storage Devices: Magnetic, Optical, Solid State.
  3. Storage Capacities: HDD (1 TB), CD (700 MB), DVD (4.7-8.5 GB), Blu-ray (25-50 GB).
  4. Advantages of Flash Storage: Durable, fast, compact, portable.
  5. Advantages of Magnetic Tape: Large capacity.
  6. Conversion to Bits: Formula provided, based on 128 GB.

Conclusion

  • Completion of Chapter 1
  • Next lesson will start Chapter 2.

Full transcript