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