Backing Storage
Hard Disk
Magnetic media
Random Access
Very fast to read and write to
Very large capacity
Up to 1 Terabyte
Used for continuous, interactive access
Can buy portable hard disks
Cost up to £200 depending on capacity
Floppy Disk
Magnetic media
Random Access
Slow to access and write to
Small capcity
up to 1.44 Megabyte
Portable
Cost approx 15p each
Magnetic Tape
Magnetic Media
Sequential Access
Slow to read and write to
Used for BACKUP (copies of files)
Cost up to £150 depending on capacity
Optical Disks
Random Access
Fast to read
CD - compact disk
CD-RW
Can be written to again and again
CD-R
Can be written to once only
CD-ROM
Cannot be written to
Capacity up to 700 Megabytes
DVD - digital versatile disk
DVD-RW
Can be written to again and again
DVD-ROM
Can be written to once only
DVD-R
Cannot be written to
Capacity normally 4.7 Gb but up to 17 Gb
Solid State
Memory Card
Random Access
Fast to read and write to
Capacity up to 16 Gb
Used for portable devices eg. digital camera
Cost up to £100 depending on capacity
USB flash drive
Random Access
Fast to read and write to
Capacity up to 64 Gb
Used as portable storage
Cost up to £150 depending on capacity