• Basic setup information & operating systems are required for the computer to function
• Application software needs to be available for the user to carry out tasks
• Files created by user needs to be stored so that they can be used again
• Data may need to be transferred from one device to another
• Backup copies need to be taken in case the original files are lost or have become corrupt

• Internal & External
• Magnetic
• Hard Disks
• Floppy Discs
• DAT tapes

• When a personal computer boots up, uses data stores in ROM to load BIOSto make the computer work
• Then it loads operating software from hard drive
• As well as immediate storage capcity (ROM & RAM), computer needs backing storage for mass storage of data & programs
• Personal computers make use of a variety of removable media

• Hard Disks
• Floppy Discs

• Day to day storage on PC systems is carried out by the hard disk
• Made up of rotating plastic/metal disks covered with magnetic coating on which the data is stored
• Available with very large storage capacity at a relatively low cost
• Fast to read, extremely reliable & robust
• If one drive fails, the other automatically take over & data remains available available for the network to use without any network down time

• Were once extremely popular
• Only holds 1.44 MB of data - no longer a pratical storage method
• Easily damaged & not very reliable

• Small in size but can hold a lot of data
• Often used to backup servers because they are easy to take away & store at a diiferent location to server
• Quite slow to write to & very slow to retrieve data
• Less reliable than hard drives & more difficult to restore selected files from
• Useful removable backup medium

• CD-ROMs & DVD-ROMs
• CD-Rs & DVD-Rs
• CD-RW & DVD-RW
• Burning data usually needs special software that formats the disc & copies the data

• Read only
• Often used to supply software 
• No further data can be written to them

• Data written to them once 
• Storage space cannot then be overwritten with new data 
• Useful for backing up files & making archive copies that are unlikely to be needed but should not be thrown away altogether

• Can have data written to them many times
• Used to transfer data between machines
• They are reusable, but most people find flash drives are more convienent for this 

• Used for portable devices (e.g. digital cameras, MP3 players, mobile phones & satelliate navigation systems)
• Popular for transferring data between machines 
• Most operating systems will recognise the drive 
• Increasingly being used as the main storage medium 

• The increased upload & download speeds made it possible by broadband internet connection = people can store their data away from their computer
• Some photograph printing companies offer sites where users can store their photographs

Need to think about:

• The volume of data to be stored
• The reason data is being stored
• Whether data will need to be rewritten
• Speed of recovery
• Physical size of device

• Email attachment
• Instant message service
• Flash Memory
• Optical discs
• Removable hard drives

•                 Storage medium needs to be extremely reliable (tape drives, optical media & extra hard drives)
• Floppy dics are too small to consider
• Flash memory is not usually considered because it is vunerable to damage