🧠 RAM vs ROM: What’s the Difference?
| Aspect | RAM (Random Access Memory) | ROM (Read-Only Memory) |
|---|---|---|
| 📖 Full Form | Random Access Memory | Read-Only Memory |
| 📥 Type | Volatile (data is lost when power is off) | Non-volatile (data is retained when power is off) |
| 🔄 Accessibility | Read & Write | Mostly Read-only |
| 🧠 Use | Temporary memory for running programs and OS | Permanent storage for system firmware (e.g., BIOS) |
| ⚡ Speed | Very fast | Slower than RAM |
| ⌛ Lifetime | Temporary, used during execution | Permanent or semi-permanent |
| 🔁 Modifiable? | Yes (frequently) | Usually No (or rarely) |
🧩 RAM: Think of it like your desk
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You work on things temporarily.
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The bigger your desk (RAM), the more tasks you can work on at once.
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When you turn off your PC, it’s like sweeping everything off the desk—RAM is cleared.
Used by OS and apps for active processes.
🧠 Types of RAM:
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DRAM (Dynamic RAM): needs refreshing (used in modern PCs)
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SRAM (Static RAM): faster, used for cache memory
🧩 ROM: Think of it like a user manual glued inside your machine
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Can’t be erased easily.
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Stores critical instructions (like how to start the system—bootloader or BIOS).
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Stays even when power is off.
Used to store firmware or permanent instructions.
🧠 Types of ROM:
| Type | Description |
|---|---|
| PROM | Programmable once |
| EPROM | Erasable with UV light |
| EEPROM | Electrically erasable (used in BIOS today) |
🔧 Real World Analogy:
| Concept | Analogy |
|---|---|
| RAM | Your short-term memory or a whiteboard you write on and erase frequently |
| ROM | A printed manual or permanent road signs—meant to be read, not rewritten often |
🧠 Interview-Ready Summary:
RAM is a volatile, high-speed memory used for temporarily storing data that the CPU is actively working on. ROM is a non-volatile memory that stores permanent instructions needed for booting the system. RAM is read-write, fast, and temporary; ROM is read-mostly, persistent, and usually slower.