Storage Devices Flashcards
1
Q
Hard Drive
A
- Uses platters coated in a magnetic material
- Iron particles are polarised to N or S state (represents 1s & 0s)
- Disk is divided into tracks , which is divided into sectors
- Disk spins very quickly at 10 000 RPM
- Needle(actuator) moves across the disk to access different tracks and sectors
- Data is read/ written to the disk as it passes under the actuator
- Hard drives can have many platters with it’s own actuator
- Very high storage capacity
2
Q
Optical disk
A
- 3 forms: read only, recordable, rewriteable
- Reflective and non reflective areas are read as 1s & 0s
3
Q
CD ROM
A
- Manufactured read only has pits and lands that vary light reflections
- Low power laser reads by shining light onto the disk and a sensor reads the levels
- Has roughly 650MB, but Blu-Ray has 50GB due to shorter wavelength used creating smaller pits allowing more pits and more tightly wound track
4
Q
CD R
A
- high powered laser burns( changes chemical properties of) sections of the surface making them less reflective
5
Q
CD RW
A
-Use laser and magnet to heat a spot and set its state to 1 or 0 using the magnet before it cools
6
Q
SSD
A
- Array of chips on a board inside what looks like a traditional HDD
- Has many NAND flash memory cells and a controller that manages pages and blocks of memory
- Faster and less power consuming than HDDs
