Here are simple notes for Class 4 students. You can also use them in your class or slides. I added definitions, examples, advantages, disadvantages, and pictures for better understanding.

Difference Between RAM and ROM

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FeatureRAMROM
Full FormRandom Access MemoryRead Only Memory
TypeTemporary memoryPermanent memory
DataData is lost when power is OFFData is not lost
UseStores programs currently runningStores startup instructions
ExampleRunning games, appsBIOS program

Example:
When you open a game on a computer, it loads into RAM.

Secondary Storage Devices

Secondary storage devices store data permanently.

Examples:

  • Hard Disk

  • SSD

  • Pen Drive (USB)

  • Memory Card

  • CD / DVD

  • Cloud Storage

1. Hard Disk Drive (HDD)

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Definition:
HDD is a storage device used to store data permanently in a computer.

Size:
500 GB – 10 TB

Approx Price (India):
₹1500 – ₹5000

Advantages

  • Large storage capacity

  • Cheaper than SSD

Disadvantages

  • Slower speed

  • Can break if dropped

2. Solid State Drive (SSD)

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Definition:
SSD is a fast storage device that stores data using flash memory.

Size:
256 GB – 4 TB

Approx Price:
₹2500 – ₹12000

Advantages

  • Very fast

  • Durable (no moving parts)

  • Less power usage

Disadvantages

  • Expensive

  • Smaller capacity compared to HDD

3. USB Flash Drive (Pen Drive)

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Definition:
A USB drive is a small portable device used to store and transfer data.

Size:
8 GB – 1 TB

Approx Price:
₹300 – ₹3000

Advantages

  • Portable and small

  • Easy to use

  • Plug and play

Disadvantages

  • Easy to lose

  • Limited storage compared to HDD

4. Memory Card

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Definition:
A memory card is a small storage device used in phones, cameras, and tablets.

Size:
16 GB – 1 TB

Approx Price:
₹200 – ₹6000

Advantages

  • Very small and portable

  • Used in mobile phones and cameras

Disadvantages

  • Can be damaged easily

  • Easy to misplace

5. Optical Storage (CD / DVD)

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Definition:
Optical storage uses laser light to read and write data on discs.

Size:
CD – 700 MB
DVD – 4.7 GB

Approx Price:
₹20 – ₹100 per disc

Advantages

  • Cheap

  • Good for music and movies

Disadvantages

  • Easily scratched

  • Low storage capacity

6. Cloud Storage

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Definition:
Cloud storage stores data on the internet instead of your computer.

Examples

  • Google Drive

  • iCloud

  • OneDrive

Size:
Depends on service (5 GB – unlimited)

Advantages

  • Access from anywhere

  • Data backup

  • Easy sharing

Disadvantages

  • Needs internet

  • Privacy risk

✅ Simple Conclusion for Students

Primary Memory

  • RAM

  • ROM

Secondary Storage

  • HDD

  • SSD

  • Pen Drive

  • Memory Card

  • CD / DVD

  • Cloud Storage

If you want, I can also make this into a beautiful PDF worksheet for Class 4 students with labeled diagrams and activity questions. 📘

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