Storage Devices in Computers
🔹 Definition:
Storage devices are hardware used to store digital data. They retain information temporarily (for processing) or permanently (for future use).
🔹 Types of Storage Devices:
🟡 1. Primary Storage (Main Memory):
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RAM (Random Access Memory): Temporary, volatile memory. Data is lost when power is off.
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ROM (Read-Only Memory): Non-volatile, contains startup instructions (BIOS), read-only.
🟢 2. Secondary Storage (Permanent Storage):
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Used to store data permanently.
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Examples: Hard Disk Drive (HDD), Solid State Drive (SSD), Optical Disks, USB, Memory Cards.
🟠 3. Tertiary Storage:
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Used for archiving large amounts of data.
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Example: Magnetic Tape, Optical Jukeboxes.
🔵 4. Cloud Storage:
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Data stored on remote servers via the internet.
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Example: Google Drive, Dropbox.
🔹 Examples of Storage Devices:
| Device | Type | Volatile | Use/Function |
|---|---|---|---|
| RAM | Primary | Yes | Temporary data storage |
| ROM | Primary | No | Stores BIOS & firmware |
| Hard Disk (HDD) | Secondary | No | Permanent data storage |
| SSD | Secondary | No | Faster permanent storage |
| CD/DVD | Secondary | No | Optical storage |
| USB Drive | Secondary | No | Portable data transfer/storage |
| Magnetic Tape | Tertiary | No | Long-term archiving |
| Cloud Storage | Remote | No | Online data storage |
📝 Important Points for Exams:
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RAM is faster but volatile.
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ROM is non-volatile and stores system firmware.
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SSD is faster and more reliable than HDD but more expensive.
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HDD uses spinning disks; SSD uses flash memory (no moving parts).
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Optical storage uses laser (e.g., CD, DVD).
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Flash Drives (USB) are portable and rewritable.
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Magnetic Tapes used for backup and archival storage.
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Cloud storage provides accessibility from any location with internet.
❓ Previous Year MCQs (PYQs)
✅ SSC/Bank/JKSSB PYQs:
-
Which of the following is volatile memory?
a) ROM
b) RAM ✅
c) Hard Disk
d) SSD -
Which device uses laser technology to read and write data?
a) SSD
b) Magnetic Disk
c) Optical Disk ✅
d) Pen Drive -
What type of storage is a USB flash drive?
a) Primary
b) Secondary ✅
c) Cache
d) ROM -
Cloud storage is based on which of the following?
a) Floppy disk
b) Remote servers ✅
c) RAM
d) Magnetic tape -
Which storage has no moving parts and is faster than HDD?
a) Optical Disk
b) SSD ✅
c) Magnetic Tape
d) ROM -
What is the full form of SSD?
a) Super Storage Drive
b) Solid State Drive ✅
c) Soft Storage Device
d) Secure Storage Disk -
Which memory is used to boot the computer?
a) RAM
b) SSD
c) ROM ✅
d) Cache
🔚 Quick Revision Points:
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RAM = Temporary, volatile, fast
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ROM = Permanent, non-volatile, stores firmware
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HDD = Mechanical, large capacity, slower
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SSD = Electronic, fast, costly
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CD/DVD = Optical storage
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USB = Flash storage
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Cloud = Internet-based storage
Important Computer Memories for Exams
🔹 1. RAM (Random Access Memory)
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Volatile memory (data lost when power is off).
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Stores data and instructions currently being used by the CPU.
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Faster than secondary memory.
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Two types:
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SRAM (Static RAM) – faster, costlier, used in cache.
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DRAM (Dynamic RAM) – slower, cheaper, used in main memory.
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🔸 Example use: Running programs like MS Word, Chrome, etc.
PYQ:
Q. RAM is a ___ memory.
a) Permanent
b) Volatile ✅
c) Flash
d) Optical
🔹 2. ROM (Read Only Memory)
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Non-volatile memory (data remains even after power is off).
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Stores firmware and BIOS (startup programs).
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Cannot be modified easily.
Types of ROM:
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PROM (Programmable ROM)
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EPROM (Erasable Programmable ROM)
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EEPROM (Electrically Erasable PROM)
PYQ:
Q. BIOS is stored in:
a) RAM
b) ROM ✅
c) Hard Disk
d) SSD
🔹 3. Cache Memory
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Very fast and small memory located between CPU and RAM.
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Temporarily stores frequently used instructions and data.
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Improves CPU speed and efficiency.
PYQ:
Q. The memory located between CPU and RAM is:
a) ROM
b) Cache ✅
c) HDD
d) USB
🔹 4. Virtual Memory
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A section of the hard drive used as RAM when physical RAM is full.
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Slower than RAM.
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Allows computers to run more applications than actual RAM permits.
PYQ:
Q. The memory created using hard disk when RAM is full is:
a) Virtual Memory ✅
b) Cache
c) ROM
d) Flash
🔹 5. Flash Memory
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Non-volatile, rewritable memory.
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Used in pen drives, SSDs, memory cards.
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Faster than HDD, slower than RAM.
PYQ:
Q. Pen drive is an example of:
a) RAM
b) ROM
c) Flash Memory ✅
d) Cache
🔹 6. Register Memory
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Smallest and fastest memory inside CPU.
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Stores current instructions and operands.
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Temporary and volatile.
PYQ:
Q. The fastest memory in a computer is:
a) RAM
b) ROM
c) Register ✅
d) Cache
🔹 7. Secondary Memory (Storage)
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Used to store data permanently.
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Non-volatile memory.
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Examples: HDD, SSD, CD/DVD, USB, Memory Card.
PYQ:
Q. Which of the following is not a primary memory?
a) RAM
b) ROM
c) SSD ✅
d) Cache
🔹 8. BIOS (Basic Input Output System)
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Stored in ROM.
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Responsible for booting up the computer.
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Performs POST (Power-On Self-Test).
📝 Quick Comparison Table:
| Memory Type | Volatile | Speed | Used For |
|---|---|---|---|
| RAM | Yes | Fast | Running programs |
| ROM | No | Slower | Boot instructions (BIOS) |
| Cache | Yes | Very Fast | CPU performance boost |
| Virtual Memory | Yes | Slow | Extra memory using HDD |
| Flash Memory | No | Medium | Storage in USB/SSD |
| Registers | Yes | Fastest | Inside CPU, instruction handling |