Meomory & Storage



1. What is Computer Memory?

computer memory photo

Computer memory is the component that stores data and instrucions for processing.

2. Types of Memory


  1. Primary Memory (Main Memory)
  2. Secondary Memory (Permanent Storage)

3. Primary Memory


RAM (Random Access Memory)
  • Volatile Memory
  • Used for temporary storage
  • Faster than ROM

ROM (Read Only Memory)
  • Non-volatile memory
  • Stores boot instructions
  • Data does not change easily

Important: RAM is Volatile, ROM is non-volatile.

4. Secondary Meomory


Secondary memory is permanent storage to store data for long term.

  • HDD - Hard Disk Drive
  • SSD - Solid State Drive(Fastest)
  • Pen Drive
  • CD / DVD
  • Memory Card

5. HDD vs SSD (Very Important)

hdd vs ssd img

HDD SSD
Slow Speed Very fast
Uses magnetic platters Uses flash memory
Cheap Expensive
More heat Less heat
Moving parts No moving parts

6. Units of Memory

unts of memory

  • 1 KB = 1024 Bytes
  • 1 MB = 1024 KB
  • 1 GB = 1024 MB
  • 1 TB = 1024 GB

Important for exam: 1 KB = 1024 Bytes

7. Cache Memory

cache memory img

Cache is a very fast memory located inside the CPU to speed up processing.

Faster than RAM

8. Virtual Memory

virtual memory iamge

Virtual Memory is when the computer uses a part of the hard disk as RAM.

Used when RAM is full.

9. Important Exam Questions


  • Which memory is volatile? → RAM
  • Which memory stores booting instructions → ROM
  • Fastest memory? → Cache
  • SSD full form → Solid State Drive
  • HDD full form → Hard Disk Drive
  • 1 KB = 1024 Bytes