Complete notes on the difference between RAM and ROM with:
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Definitions
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Key differences
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Important points for exams
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MCQs (including previous year questions from SSC, Bank, JKSSB)
Definition of RAM (Random Access Memory)
RAM (Random Access Memory) is a type of volatile memory in a computer that temporarily stores data and instructions that the CPU needs while performing tasks. Once the computer is turned off, all data in RAM is lost.
RAM is volatile – data is erased when power is off.
RAM is readable and writable – the CPU can both store and retrieve data.More RAM = faster performance in multitasking.
RAM is used by applications and the Operating System (OS) to run efficiently.
When you open MS Word and type a document, it is temporarily stored in RAM. If the power goes off before saving, your data is lost — because RAM is temporary.
Definition of ROM (Read-Only Memory)
ROM (Read-Only Memory) is a type of non-volatile memory in a computer that permanently stores essential data and instructions needed to start and operate the system. The data in ROM cannot be modified easily and remains intact even when the power is turned off.
ROM is non-volatile – data remains even after power off.
Stores BIOS, firmware, and boot instructions.Mostly read-only, though some types like EEPROM can be modified.
Data is written during manufacturing or firmware updates.
🧠 Difference Between RAM and ROM
| Feature | RAM (Random Access Memory) | ROM (Read-Only Memory) |
|---|---|---|
| Full Form | Random Access Memory | Read-Only Memory |
| Type of Memory | Volatile memory | Non-volatile memory |
| Data Storage | Stores data temporarily (while PC is on) | Stores data permanently (even if PC is off) |
| Usage | Used for current tasks and operations | Used to store firmware (BIOS, bootloader) |
| Data Modification | Can be read and written | Usually only read, not written |
| Speed | Faster than ROM | Slower than RAM |
| Example | DDR4 RAM, DDR3 | BIOS, EEPROM, PROM |
| Cost | Expensive | Cheaper than RAM |
🔍 Important Points for Exam
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RAM is temporary memory, meaning it loses data when power is turned off.
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ROM is permanent memory, used to store startup instructions.
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RAM is essential for running applications, while ROM is essential for booting the computer.
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ROM is read-only, but EEPROM and Flash ROM can be rewritten.
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RAM is much faster but costlier than ROM.
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RAM size is usually in GBs (e.g., 8GB, 16GB), ROM size is usually MBs (e.g., 512MB BIOS).
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Without RAM, the system won’t run applications. Without ROM, the system can’t start.
📘 MCQs (RAM vs ROM)
✅ Frequently Asked/Previous Year Questions (SSC, Bank, JKSSB)
Q1. What type of memory is lost when the computer is turned off?
A. ROM
B. RAM
C. HDD
D. SSD
✅ Answer: B. RAM
Q2. ROM stands for:
A. Read Only Memory
B. Run On Memory
C. Real Original Memory
D. Random Operating Memory
✅ Answer: A. Read Only Memory
Q3. Which of the following is a volatile memory? (JKSSB 2021)
A. ROM
B. HDD
C. RAM
D. CD-ROM
✅ Answer: C. RAM
Q4. Which memory stores BIOS in a computer? (SSC CHSL 2020)
A. RAM
B. Cache
C. ROM
D. Registers
✅ Answer: C. ROM
Q5. RAM is also known as:
A. Permanent memory
B. Temporary memory
C. Flash memory
D. External memory
✅ Answer: B. Temporary memory
Q6. Which of the following is non-volatile? (Bank PO Pre 2019)
A. DRAM
B. SRAM
C. ROM
D. Cache
✅ Answer: C. ROM
Q7. In which type of memory data cannot be modified easily? (JKSSB 2022)
A. RAM
B. ROM
C. Cache
D. Hard Disk
✅ Answer: B. ROM
📌 Quick Revision: One-liners
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RAM = Temporary + Volatile + Fast
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ROM = Permanent + Non-volatile + Boot info
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RAM is erased when PC is turned off.
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ROM holds data even after shutdown.