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3.1 Storage
OverviewCompare the following storage devices in terms of storage capacity, cost, speed of data retrieval and suitability for specific purposes:
Hard disk DVD CD-RW CD-ROM/CDR Blu-ray Tape streamer Flash media
Units of Storage
• Bit• Byte• MB – Megabyte• GB – Gigabyte
Hard disk
• Main storage device in most computer systems
• Magnetic storage device
• A number of disks one on top of the other in a sealed unit
• Lacks portability• Holds a lot of
information
Digital Versatile Disk
• Looks like a CD• Requires a DVD drive• Typical storage capacity
17GB
CD-RW
• CD Rewriteable• Can be written to and
erased many times• More expensive than a
CD-R• Needs a CD-RW drive
CD-ROM
• Compact Disk Read Only Memory
• Information cannot be erased
• Typical storage is 650MB
• Faster access than a floppy access
• More robust than a floppy disk
Blu-ray• An optical storage medium• Huge capacity• Do not necessarily need special equipment to read
them• Popular applications are the storage of video and
high definition graphics
Tape Streamer
• Digital audio tape• A magnetic medium• Serial access medium• Has a huge storage
capacity typically 60GB• Used for backup
Flash Media
• Non-volatile computer storage
• Can be electrically erased and reprogrammed.
• Usual applications are memory cards and USB flash drives
Network storage v Local storage
Network storage• Network administrator
backs it up• Peripherals can be
shared
Local storage• Up to the individual to
back it up• Every system needs its
own peripherals
Acronyms
• MB Megabyte• GB Gigabyte• DVD Digital Versatile Disk• CD Compact Disk• CD-R Compact Disk Recordable• CD-ROM Compact Disk Read Only
memory• DAT Digital Audio Tape
Associated words
• Primary storage• Secondary storage• Serial access• Direct access• Optical storage• Magnetic storage• Backing store
Complete the following:
Capacity Cost Speed of data retrieval
Application
DVD
Hard disk
CD-ROM
Flash memory
Floppy disk
Tape streamer