3.3 · Lesson 2 of 4
Secondary storage: HDD and SSD
Syllabus 3.3.2Syllabus 3.3.3
What this lesson covers
- Describe secondary storage
- Explain how magnetic, optical and solid-state storage work
Key vocabulary
- Secondary storage
- Non-volatile, long-term storage that isn't directly accessed by the CPU.
- Magnetic storage
- Stores data by magnetising tiny areas of a surface, e.g. a hard disk drive.
- Platter
- A circular magnetic disk inside an HDD where data is stored.
- Read/write head
- Moves across the platter on an actuator arm and uses an electromagnet to read and write data.
- Track
- A circle all the way round a platter. Tracks are concentric.
- Sector
- A wedge-shaped section of a platter that splits each track into blocks.
- Latency
- The time spent waiting for the data to rotate round to the read/write head.
- Solid-state storage
- Storage with no moving parts that uses flash memory (NAND or NOR).
- Floating gate
- Part of a flash memory transistor where electrons are trapped to store data, even without power.
Check your learning
- Quick check: 4 questions
- Key vocabulary test: 9 terms
- Activity 1: HDD or SSD? · drag and drop
- Activity 2: Choose the drive · 8 questions
- Activity 3: Secondary storage quiz · 8 questions