Upload
forrester-high-school
View
3.482
Download
1
Tags:
Embed Size (px)
DESCRIPTION
Backing Storage
Citation preview
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