Storage Devices Flashcards
What is a computers primary memory storage?
Random Access Memory (RAM)
What is the advantage of secondary storage?
It retains its contents when the computer’s power is turned off
What is the disadvantage of secondary storage?
It is not directly accessible to the processor and has slower access speeds
What are some examples of secondary storage?
The computer’s internal hard disk, optical media and solid state disks
How do hard disk work?
A hard disk uses rigid rotating platters coated with magnetic material, iron particles on the disk are polarised to become either north or south state, representing 0 and 1, the disk is divided into tracks in concentric circles, and each track is subdivided into sectors, the disk spins at up to 10,000 RPM, the drive head moves across the disk to access different tracks and sectors, and data is read from or written to the disk as it passes under the drive head
What is a disadvantage of a hard disk?
They are less portable than optical or solid state media
What is a advantage of a hard disk?
They have huge capacities with the newer 3.5 inch disk have capacities of up to 640GB
What are the 3 different formats of optical disks?
Read-only (CD-ROM), recordable (CD-R) and rewritable (CD-RW)
How does an optical disk work?
An optical disk works by using a high powered laser to ‘burn’ sections of its surface, making them less reflective, a laser at a lower power is used to read the disk by shining light onto the surface and a sensor is used to measure the amount of light that is reflected back
In a optical disk what is the parts of the surfaces that have been ‘burned’ called?
Pits
In an optical disk what are the lands that have not been pitted called?
Lands
How much data does a CD-ROM hold?
Around 700MB
How does recordable disk work?
They use a reflective layer with a transparent dye coating that becomes less reflective when it is ‘burned’
How much data does a Blu-ray hold?
Around 50GB
How does a Blu-ray disk hold more data than a CD-ROM
It has smaller pits
