IGCSE Computer Science Paper 1 Definitions Worksheet: 3.3 Data Storage (Modules 304–313)
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Key terms
Write what each term means, in your own words.
1
secondary storage
2
platter
3
magnetise
4
HDD
5
pits and lands
6
CD, DVD and Blu-ray
7
solid-state storage
8
floating gate transistor
9
NAND and NOR flash
10
SSD, SD card, USB drive
Answer Key
IGCSE Computer Science Paper 1 · Modules 304–313 · Student wording will vary for definitions
1secondary storage — Permanent, non-volatile storage with a much larger capacity than RAM. It keeps files, programs and the OS safe when the power is off, because RAM is volatile and too small.
2platter — A spinning circular disk in magnetic storage. Its surface is split into tracks (concentric circles) and sectors (sections of a track), where data is stored as magnetised areas.
3magnetise — A read/write head uses an electromagnet to magnetise tiny areas of the spinning platter to store 1s and 0s, and reads the data back by detecting the magnetic pattern.
4HDD — Hard disk drive: a magnetic storage device with spinning platters and moving read/write heads. It gives large capacity at low cost, but is slower and more fragile than flash.
5pits and lands — Dents (pits) and flat areas (lands) along a disc's spiral track. A laser reads them by how light reflects: lands reflect it back, pits scatter it. The changes store binary data.
6CD, DVD and Blu-ray — Optical discs read by laser. Capacity rises CD, DVD, Blu-ray as each laser's shorter wavelength packs pits closer. Blu-ray uses blue-violet. Discs are read-only or recordable.
7solid-state storage — Storage that keeps data in flash memory chips with no moving parts. It is non-volatile, so data stays when power is off. Examples are SSD, SD card and USB drive.
8floating gate transistor — A flash memory cell: a transistor with a control gate and a floating gate that traps charge for one bit value and none for the other, so the bit stays stored when power is off.
9NAND and NOR flash — The two ways of arranging flash transistors, named after logic gates. NAND gives high capacity (SSDs, SD cards); NOR gives faster random reads (stored program code).
10SSD, SD card, USB drive — Flash-based solid-state devices: an SSD is the main storage in a laptop, an SD card suits cameras and phones, and a USB drive is a portable stick for carrying files.