Q.What is the need of RAM? How does it differ from ROM?
You're viewing a preview — the full solution, concept, methods & PYQ mapping are locked.
Start your 14-day free trial to unlock the full solution →RAM is the fast, volatile working memory into which every program must be loaded before the CPU can execute it; ROM is small, non-volatile, essentially read-only memory holding the permanent startup instructions.
Why RAM is needed — the memory-hierarchy idea. The CPU works at enormous speed, but it can only fetch instructions and data from primary memory, not directly from a hard disk or pen drive, which are thousands of times slower. If the CPU had to wait for the disk for every instruction, it would sit idle almost all the time. So the system keeps a fast intermediate store — RAM — between the CPU and secondary storage:
- When you start a program, the OS loads it from secondary storage into RAM; only then does execution begin.
- RAM holds the operating system, all currently running programs, and their intermediate data/results.
- "Random access" means any memory location can be read or written directly in the same amount of time, which suits the CPU's jump-anywhere access pattern.
RAM is, however, volatile: switch the power off and everything in it disappears. That is why RAM can never replace secondary storage — and why unsaved work is lost in a power cut.
How RAM differs from ROM. ROM (Read Only Memory) is the other kind of primary memory, with an entirely different job: it permanently stores the small program the computer needs the moment it is switched on (the power-on self-test and boot loader that locate and load the OS).
| Point | RAM | ROM |
|---|---|---|
| Volatility | Volatile — erased at power-off | Non-volatile — retained without power |
Unlock everything free for 14 days
- Full step-by-step solutions
- Concept-first explanations
- Methods, shortcuts & mistakes
- PYQ mapping + timed mock tests
Full access for 14 days. No credit card required.