Cambridge IGCSE Computer Science (0478) · lesson 19 of 35 · 20 min
Why Secondary Storage?
RAM is fast but volatile and expensive. Secondary storage provides large-capacity, non-volatile, persistent storage for the operating system, applications, and user files. Data survives power-off.
Types of Secondary Storage
HDD vs SSD
HDD: Uses spinning magnetic platters and a read/write head that moves to the correct track. Random access is slow because the head must physically move. Susceptible to damage from drops and vibration.
SSD: Uses NAND flash memory chips — no moving parts. Random access is near-instant. Silent, more energy-efficient, and far more durable. More expensive per GB than HDD.
Which storage type uses spinning magnetic platters?
- SSD
- USB flash drive
- HDD
- Optical disc
Answer: HDD
HDDs use spinning magnetic platters with a moving read/write head.
Why is an SSD faster than an HDD for random access?
- SSDs spin faster
- SSDs have no moving parts — access is electronic
- SSDs use optical technology
- SSDs have larger cache
Answer: SSDs have no moving parts — access is electronic
SSDs use flash memory with no mechanical movement, so access is near-instant.
Which storage medium is most suitable for distributing software to customers?
- HDD
- SSD
- Optical disc (DVD)
- RAM
Answer: Optical disc (DVD)
Optical discs are cheap to mass-produce and suitable for software distribution.
Previous lesson: Primary memory: RAM and ROM
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