Chapter 7 - Storage
By Chris Wilson
Storage
 Holds data, instructions, and information for
future use.
 Storage Medium(secondary storage) – The
physical material on which a computer holds
data. Ex: floppy disks, hard disks, CDs,
DVDs, tape, ZIP disks, PC cards.
 Capacity – Number of bytes a storage
medium can hold.
Storage Device
 The computer hardware that records and/or
retrieves items to and from storage media.
 Writing – process of transferring data to a storage
medium
 Reading – process of transferring these items from
a storage medium into memory.
 Access time – amount of time it takes a storage
device to locate an item on a storage medium.
Floppy Disks
 Floppy Disk(diskette) – A portable storage medium
that consists of a thin, circular, flexible plastic
Mylar film in a square plastic shell.
 Magnetic media – Uses magnetic particles to store
items in tracks and sectors.


Tracks – narrow recording band that forms a full circle on the
disk
Sector – arc shaped storage locations that make the tracks.
ZIP Disk
 ZIP disk – A type of portable magnetic media
that can store up to 500 times more than a
standard floppy.
Hard Disk
 Hard Disk(hard disk drive) – A storage
device that contains one or more inflexible,
circular platters that store data, instructions,
and information.
 Platter – A 3.5 or 5.25in disk made of
aluminum, glass, or ceramic and is coated
with an alloy material that allows items to be
recorded magnetically on it’s surface.
How a Hard Disk Works
 A platter will spin around at a rate of 5,4007,200rpms, while a reader/writer head floats
above the platter at ~two millionths of an
inch.
 Cache – location where frequently used items
are store to improve efficiency.
Types of Hard Disks
 Internal – Permanently inside the CPU.
 External – A separate freestanding hard disk
that connects with a cable to a USB port.
Internet Hard Drives
 Internet Hard Drive – a service on the web
that provides storage to computer users,
usually for a minimal fee.

Allows users to to access files from any computer of
device that has Internet access.
CDs and DVDs
 CDs and DVDs – storage media that consists
of a flat, round, portable metal disc with a
protective plastic coating.
An optical media that stores items by using
microscopic pits (indentations) and lands (flat areas)
 A high –powered laser light creates the pits, and a
lower-powered laser reads items by reflecting light
through the bottom of the disc.

CD-ROMs and CD-RWs
 CD-ROM – Optical disc that holds from 650MB to
1 GB of data. Users can read information from
these discs but can not modify them.
 CD-R (compact disc-recordable) – A multisession
disc that users can record their own information
once only
 CD-RW(compact disc-rewritable) – A disc in which
users can write, and then re-write new information.
DVD-ROM and DVD+RWs
 DVD-ROM(digital versatile disc-ROM or
digital video disc) – an extremely high
capacity optical disk capable of storing from
4.7 GB to 17 GB.
 DVD+RW – A recordable version of DVD
that allows users to erase and record more
than 1,000 times.
Tape
 Tape – a magnetically coated ribbon of
plastic capable of storing large amounts of
data and information at a low cost.
 Tape drive – Device that reads and writes
data and information on tape.
PC Cards and Types of
Miniature Storage Media
 PC Card – A thin credit-card sized device
that fits into a PC Card slot to add storage or
other capabilities to a desktop or notebook
computer.

Examples: PDA;s, digital cameras, music plaers.
 Miniature mobile storage media – Compact
flash, Memory stick, Secure digital, Smart
Media.
Microfilm and Microfiche
 Microfilm – A 100-215ft roll of film used to
store back issues of newspapers, magazines,
and records.
 Microfiche – A small sheet of film usually
about 4 by six inches used in the same
fashion as microfilm.