Transcript Hard Disk and Optical disks

McGraw-Hill Technology Education
McGraw-Hill Technology Education
Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved.
Chapter 5A
Types of Storage
Devices
McGraw-Hill Technology Education
Copyright © 2006 by The McGraw-Hill Companies, Inc. All rights reserved.
Describing Storage Devices
• What is Formatting?
• The process of preparing the Storage
device to store data is called formatting.
6A-3
Describing Storage Devices
• Storage terms
– Magnetic devices use a magnet
– Optical devices use lasers
– Solid-state devices have physical switches
6A-4
Magnetic Storage Devices
• Most common form of storage
• Hard drives, floppy drives, tape
• All magnetic drives work the same
6A-5
Magnetic Storage Devices
Floppy Disk
Hard Disk
Tape
6A-6
Data Retrieval
6A-7
Magnetic Storage Devices
• Data organization
– Disks must be formatted before use
– Format draws tracks on the disk
– Tracks is divided into sectors
• Amount of data a drive can read
6A-8
Tracks and Sectors
6A-9
Magnetic Storage Devices
• Finding data on disk
– Each track and sector is labeled
• Some are reserved
– Listing of where files are stored
• File Allocation Table (FAT)
• FAT32
• NTFS
– Data is organized in clusters
• Size of data the OS handles
6A-10
Magnetic Storage Devices
• Hard disks
– Primary storage device in a computer
– 2 or more aluminum platters
– Each platter has 2 sides
– Spin between 5,400 to 15,000 RPM
– Data found in 9.5 ms or less
– Drive capacity greater than 40 GB
6A-11
Illustrated Hard Disk
6A-12
Optical Storage Devices
• CD-ROM
– Most software ships on a CD
– Read using a laser
• Lands, binary 1, reflect data
• Pits scatter data
– Written from the inside out
– CD speed is based on the original
• Original CD read 150 Kbps
• A 10 X will read 1,500 Kbps
– Standard CD holds 650 MB
6A-13
Optical Storage Devices
• DVD-ROM
– Digital Video Disk
– Use both sides of the disk
– Capacities can reach 18 GB
– DVD players can read CDs
6A-14
Recordable Optical Technologies
• CD Recordable (CD-R)
– Create a data or audio CD
– Data cannot be changed
– Can continue adding until full
6A-15
Recordable Optical Technologies
• CD Regrettable (CD-RW)
– Create a reusable CD
– Cannot be read in all CD players
– Can reuse about 100 times
6A-16
Recordable Optical Technologies
• DVD Recordable
– Several different formats exist
– None are standardized
– Allows home users to create DVDs
– Cannot be read in all players
6A-17
Recordable Optical Technologies
• DVD-RAM
– Allow reusing of DVD media
– Not standardized
– Cannot be read in all players
6A-18
Blu Ray
6A-19
• It’s a New technology DVD that Uses a
special blue laser to store more data than a
normal Red Laser DVD.
• The Wavelength of Blue laser is much lesser
than of Red laser that’s why it can store more
data then DVD.
• Blu-Ray Disc needs a wavelength of 400
nanometer violet-blue laser for its reading.
• BD is present in both single layer and double
layer. The single layer Blu-Ray Disc has a
capacity of up to 25 GB and double layer has
a capacity of 50 GB.
Blu ray and DVD Working
6A-20
DVD Dual Layer
• The term "DVD DL" (DVD Dual Layer)
refers to DVDs which can be recorded
on two separate layers. These discs,
which have more storage space than
single-layer DVDs, use a technology
similar to that of DVD-9 (dual-layer
discs).
6A-21
Working of Dual Layer
• The power of laser increased when it
needs to read the 2nd layer.
6A-22