what storage devices use magnetic storage
HDD, magnetic tape
what storage devices use optical media
CD, DVD, blue ray
what storage devices use solid state storage
SSD, USB flash drive, memory cards
what does solid state use to store data
flash memory
how does magnetic storage work
a read/write head moves over a spinning platter to magnetically read or write data
magnetic storage characteristics
larger capacity, cheaper per GB, slower than SSD, can wear out over time
how does optical storage work
data is stored as a series of pits and lands on the disc. A laser shines on the disks, a pit scatters light = 0, a land reflects light directly = 1, for writting a high powered laser burns pits into the disk
optical storage characteristics
portable and lightweight, low capacity, prone to scratches
how does flash memory work (SSDs)
each memory cell stores bits using electrical charge, charge =1, no charge =0, data is read or written by applying voltage to these cells, to write electrons are pushed in, to read they are removed
how does a HDD work
it contains 1 or more spinning platters coated with a magnetic material, a read/write head moves across the disks surface, data is stored by magnetising tiny regions on the disks in different directions, the had can change the magnetism to write data or detect it to read data, data is organized into tracks and sectors
what enables optical media to be re written
special metal layer that can be changed with heat from a laser
advantages of solid sate (flash memory)
fast ,durable, low power
HDD key points
moving parts, larger capacity, slower than SSD due to movement, sensitive to drops
