hardware l4 how storage devices work diff.pptx
TRANSCRIPT
GCSEAQAComputer ScienceComponent 2
How storage devices work
Unit 2Hardware
4
Objectives• Understand how magnetic media, optical media and
solid state work
How storage devices workUnit 2 Hardware
Three main types of storageName Description Image
Magnetic
Mechanical parts move over the disks surface to read and write data magnetically
Optical Lasers read and write data using light
Solid State
Data is recorded onto solid memory chips without any moving parts
How storage devices workUnit 2 Hardware
Magnetic DisksBasic Features
Disk contains circles called tracks
Each track is divided into sectors
Disk heads read and write the data
How storage devices workUnit 2 Hardware
Magnetic disk – how does it work?
How storage devices workUnit 2 Hardware
Optical (CD / DVD/ Blu-Ray)Basic Features
Data is stored as pits and lands burnt into a spiral trackA laser beam passes over and measures the amount of reflectionThe reflections are turned into 1’s and 0’s
How storage devices workUnit 2 Hardware
How a CD Works
How storage devices workUnit 2 Hardware
Solid State StorageBasic Features
Non- volatile flash memory to store informationVery fast read/write speeds
No mechanical or moving parts
How storage devices workUnit 2 Hardware
How flash memory works• Large electric current used to force electrons
through a barrier and trap them on the other side
• They remain on the other side until “flashed” with a new current, hence the name
• Trapped (charged) or not trapped = 0 or 1
Electrons trapped in this layer
Electrons detected here
Current applied and electrons forced through barrier
Barrier
How storage devices workUnit 2 Hardware
Worksheet 4• Secondary storage devices
• Use the ASCII Codes sheet to help you