Storage and memory devices

Made by: Muhammad Hassaan Arif

1

A data storage device is a device for
recording (storing) information (data).




A plastic tape coated with iron oxide for use in
magnetic recording.



Magnetic tape is a serial access medium, similar
to an audio cassette, and so data cannot be
quickly located.



However large amounts of information can be
stored within magnetic tape. This characteristic
has prompted its use in the regular backing up of
hard disks.

 The

primary computer storage device. Like
tape, it is magnetically recorded and can be
re-recorded over and over.

 Disks

are rotating platters with a mechanical
arm that moves a read/write head between
the outer and inner edges of the platter's
surface.

 Common
–
–
–

types are:

Hard disks
Floppy disks
Zip disks

 It

can take as long as one second to find a
location on a floppy disk to as little as a couple
of milliseconds on a fast hard disk.


 Memory

is a temporary workplace where the
computer transfers the contents of a file while
it is being used.

 Random

Access Memory (RAM) is a
computer storage location that allows
information to be stored and accessed quickly
from random locations.


 Storage,

also known as mass media, refers to
the various media on which computer system
can store data.

 Hard

drive is one of them. There are some
features such as:





High capacity disk.
Most common media of storage.
Use one or more metal magnetic disks.

2

 The

type of operations they perform.

 The

method they use to access the information.

 The

technology they use.

 Their

capacity and speed.


3




A disk is formatted; it is divided into tracks
and sectors, and a file allocation table (FAT) is
created.

 Track

– circular band
 Sector – pie shaped section
 Cluster – two or more adjacent sectors
 FAT – keeps tracks of specific locations of files


 Floppy

Disk
Capacity – 720 KB to 1.44 MB
 Hard

Drive
Capacity – up to 1000 GB ( 1 TB)
 CD

ROM/DVD
Capacity – CD ROM 650 MB
– DVD 17 GB

 High

– density floppy disks that are commonly
used today store 1.44MB and 2.8MB of data.

A

disk or diskette is a portable storage medium.



Low capacity removable disk.



Not widely used today.

.


4

 CD-ROM

stand for compact disc read only

memory.
 CD-ROM drives can not write data to disc.
 They are capable of storing 650 MB of data.
 They are used for operating system; large
application programs.


CD-R
 Discs

can only be
written to “once”

CD-RW
 Discs

are erasable

 Discs

 CD-R

drives are
capable of reading
and writing data.

can be written
to many times

 CD-RW

drives are
capable of reading,
writing and erasing
data


 DVD

stand for Digital Video Disc.

 DVD

technology is similar to CD-ROM
technology.

 DVDs

are capable of storage up to 17GB of

data.
 DVD-R

and DVD-RW drives have the
ability to read and write data.

 Solid

state storage devices use
nonvolatile memory chips to retain
data.

 They

do not have moving parts.

 They

are small, lightweight, reliable
and portable.

Storage and memory devices

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