Magnetic Disks

Floppy drive and diskPortable 3.5 inch disc with a limited capacity of 1.4 Mb.

Zip drive and diskSlightly larger and more durable version of a floppy disc. Can store up to 750 Mb and has a faster access time.

Magnetic Disks

Hard disk drive• Fixed disk inside a computer• Has the fastest access time of any storage device• Has capacities ranging from 80 Gigabytes to several Terabytes

Magnetic Tape

Tape is very slow to access – access is linear.

Mainly used for backups.

8mm Tape• 8mm tape was originally designed for the video industry • Tapes can store up to 14 Gb with access speeds of 1Mb / sec

Magnetic Tape

Digital Linear Tape (DLT) • Tapes can store up to 70Gb with access speeds of 20 Mb/sec• Super DLT can store up to 320GB with transfer speeds of 32 Mb/sec

Digital Audio Tape (DAT)• Originally conceived as a CD quality audio format• Later became suitable for computer backing storage• Tapes can store up to 40Mb and have access speeds of 2Mb/sec

Optical Drives

The information is recorded onto the disk in the form of pits and lands.

Pits are raised, lands are lowered.

Optical technologies involving the use of lasers have contributed to the production of CD and DVD drives.

Land

Pit

Optical Drives

The drive uses a lower powered laser to scan the disk as it turns.

The light is reflected from the pits and lands, on the disc surface, differently and it is this pattern of reflection that indicates the data read.

Optical Media

CD-ROM A CD-ROM disk is a read only medium whose contents cannot be altered once data is written to it.

Capacity of a CD is approximately 700Mb

CD-R CD-R drives allow CD-ROMs and audio CDs to be written to, but only one time.

Optical Media

CD-RW (ReWritable)CD-RW drives enable CDs to be written onto it in multiple sessions.

DVD-R, DVD-RW, DVD+R, DVD+RW, DVD-RAMDVDs use an optical technology that uses a higher laser wavelength than CD. This means that tracks can be smaller and closer together and pits in the surface can be smaller.

Capacity is either 4.7 or 8.4 Gb

Data Transfer Rates

CD-ROMs150 Kb/sec

DVD-ROMs1.32 Mb/sec

This is the transfer rate for 1x CD-ROMs / DVD-ROMs

But most CD-ROMs / DVD-ROMs run faster than thise.g. 4x, 32x, 48x

Data Transfer Rates

CD-ROMs150 Kb/sec

DVD-ROMs1.32 Mb/sec

This CD-ROM is 52x, so access rate is up to

52 x 150Kb/sec

= 7.8Mb/sec

Blu-Ray

Blu-Ray is the next generation of optical storage device

It uses a narrower laser (blue) than the laser used for CD / DVD (red)

Capacity is 27Gb or 54Gb

Access speeds range from 4.5 Mb per second to 54Mb per second

Solid State Devices

Made from Electrically Erasable Programmable Read-Only Memory (EEPROM)

Physically very small and portable

No moving parts therefore not damaged by movement

Capacities are now increasing to 512 Gb

May well replace hard disk drives in computers

Solid State Devices

Memory Cards

Used for storage:• Digital cameras• Mobile phones• MP3 players

Standards include: • SD Card• Mini SD Card• Micro SD Card• Compact Flash• Secure Digital• Memory Stick/Pro• XD-Picture Card Compact Flash SD Card Micro SD Card

Solid State Devices

Memory Card Reader/Writer

• Allows Flash cards to be attached too a USB device.• Installed in some PC’s.• Allows data to be read from peripherals without the use of cables.

Solid State Devices

USB Flash Memory

• EEPROM memory chip with a USB plug.• When it is plugged in, the computer will automatically recognise it and the files can be transferred to and from the device.

Development Trends in Storage devices

Increased capacity

Investigate:

• Hard drive capacity• Flash drive capacity• Optical media capacity

Development Trends in Storage devices

Increased read / write speeds

Investigate:

• Hard drive speeds• Flash drive speeds• Optical media speeds• DLT tape speeds

• USB 2.0 speeds• Firewire speeds

Development Trends in Storage devices

Reduced physical size

Investigate:

• Hard drive size• Flash card size

Development Trends in Storage devices

Cost per unit of storage (£ per Gigabyte)

Investigate:

• Internal Hard drive storage cost• External Hard drive storage cost• USB Flash drive storage cost• DVD-R storage cost• CD-R storage cost

CreditsHigher Computing – Peripherals – Types of Storage

Produced by P. Greene for the City of Edinburgh Council 2004

Adapted by M. Cunningham 2010

All images licenced under Creative Commons 3.0• Hard Disk by Jeff Kubina• 1.44mb Floppy Disk by FreeFoto.com• 100 MB ZIP drive by Benutzer KMJ• 100 MB ZIP disk by Benutzer KMJ• Hard disk (opened) by Toshiyuki IMAI• Disco compacto 80 minutos y 700Mb by Mary Mozqueda• "Black-white 2 Vista" icon theme by DBGthekafu• Blu-ray disc logo by Sony & Panasonic• Multiple memory card reader writer by Quirren• Magnifying glass icon by G Ambrus• USB drive by Evan Amos