Transcript Raymond Washington - California State University, Fresno

Raymond Washington
Secondary Storage
Chapter 8
Traditional Floppy Disk
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The Traditional Floppy Disk is the 1.44 MB 31/2inch disk. They came out about 20 years ago
and still use today.
The most common one is labelled 2HD which
means two-side, high-density.with the two-side
label data can be saved on both sides.
This disk has the capacity of 1.44 megabytes
which is about 350 typewritten pages.
The floppy has a thin exterior jacket made of
plastic to protect the flexible disk.
There is a shutter on the disk that slides to the
side to expose the recording surface. There is
also a label to name the disk.
There is a write-protection notch that slides
open and close. Files can be read in any
direction.
Files are stored and organized on the floppy
according to tracks and sectors. Tracks are
rings of concentric circles with out visible
grooves.
Sectors tracks that are divided into invisible
wedge-shaped sections. Each can store 512
bytes.
High Capacity Floppy Disks
Known as the floppy-disk cartridge. Also has 31/2 inch diameter. But are
able to store more information, are thinker and require different
kind of special drive:
Zip disks have 100 MB, 250 MB, or 750 MB capacity. Internal zip drives
are standard on many of today's system units.the external one are
usually connected to the system unit using a UBS port.
HIFD disks from Sony and holds a capacity of 200 MB or 720 MB. It is
able to read data on today's traditional disks as well as they could
on their own.
Super Disks are made from Imation and have a capacity of 120 MB or
240 MB.just like HIFD disk they are able to use traditional disks.
Hard-Disk Cartridges
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Known as removable hard disks and are easy
to remove as a cassette from a videocassette
recorder.
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The amount of storage on a computer system
is limited only by the number of cartridges.
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Use to complement a internal hard disk.
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Hard disks have capacities of 10 to 20 GB.the
most common use one is from Iomega called
Peerless disk.
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For note book computers they have the PC
Card hard disk they credit card size and holds
up to 5 GB.
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Well known IBM’s Microdrive and Toshiba's
MK5002.
Internal Hard Disk
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Also known as fixed disk disk is located inside system
unit.
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Is designated as the C drive.
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Is use to store programs and large data files.
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Two advantages over floppy: Capacity and access speed.
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It has a 100-gigabyte internal hard disk which can hold
as much information as 70,000 standard disks.
Performance Enhancements
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Disk caching improves hard-disk performance by anticipating data needs. It
performs a function similar to Ram caching.
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Redundant arrays of inexpensive disks (RAID) improve performance by
expanding external storage, improving access speed, and providing reliable
storage.
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File compression and file decompression increase storage capacity by
reducing the amount of space required to store data and programs.
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File compression programs scan files for ways to reduce the amount of
required storage.
Compact Disc
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Compact Disc is also known as a CD. It is
one of the most widely used optical
formats. CD drives can hold 650 MB to 1
GB.
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Read only-CD-ROM ( COMPACT DISCREAD ONLY MEMORY). This means it can
not be written on or erased by the user.
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Write once-CD-R (CD Recordable). It can
only be written to once after that it can
be read many times. It can not be
erased.
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Rewriteable-CD-RW (compact disc
rewritable). Similar to CD-R, but disc
surface is not permanent. Mostly used to
edit and create multimedia presentations.
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Picture CDs/Photo CDs use a special
format developed by Eastman Kodak to
store digital images.
Digital Versatile Disc
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DVD stands for digital versatile disc or digital video disc.
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DVDs and CDs are very similar DVD disc can store 4.7 GB to 17 GB on a single DVD
disc-17 times the capacity of CDs.
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Read only-DVD stands for digital versatile disc-read only memory it provide over two
hour of very high-quality video and sound comparable to what's found in motion
pictures theatres.
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Write once-DVD-R and DVD+ are two competing write once format. Both stand for
DVD recordable.
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DVD-R and DVD+R drives are typically used to create permanent archives for large
amounts of data and to records videos.
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Rewritable- three most widely used formats are DVD-RW,DVD+RW, and DVD-RAM.
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DVD-RW and DVD+RW stands for DVD rewritable. DVD-RAM stands for DVD
random-access memory.
DataPlay
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Is an optical write once format
similar to CD-R.
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Size of a quarter with the
capacity of 500 MB or enough
to hold five hours of CD-quality
sound.
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Uses includes storing and
playing music files.
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The music industry supports
these the most.
Solid- State Storage
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Solid-state storage devices have no moving
parts. Data and information are stored and
retrieved electronically directly from these
devices much as they would from conventional.
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Flash memory cards are solid-state storage
devices widely used in notebook computer.
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Flash memory is also used in a variety of
specialized input devices to capture and transfer
data to desktop computer.
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Key chain hard drives have recently been
introduction. Key chain flash memory devices are
compact and can be transported on a key ring or
a necklace.
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Key chain hard drives conveniently connect direct
to a computer’s UBS port to transfer files and
have typical capacities of 1 GB.
Internet Hard Drives
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User storage site on the internet. Also known as I-drive or online storage.
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The advantages over other secondary storages is the lower cost and
flexibility to access information from any location using the internet.
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Access speed is a little slower because information has to travel all across
the internet.
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Often used as a specialized secondary storage device.
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Sites focus on supplying services to businesses or to individuals.
Magnetic Tape
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Sequential access and direct access are the
two different approaches to external
storage.
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Tapes provides slower sequential access
and disk provides fast direct access.
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Like the floppy and hard disk magnetic tape
stores data and programs by altering the
electromagnetic charges on a recording
surface.
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Computers once used exclusively used
magnetic tape reels.
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This type of tape is ½-inch wide and 1 ½mile long and provides a massive storage.
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Today computers use tape cartridges or
magnetic tape streamers to back up data.
The End