The document discusses various storage devices used in computers. It describes magnetic storage devices like diskettes, hard disks, high capacity floppy disks, disk cartridges, and magnetic tape. It also outlines optical storage devices such as CD-ROM, DVD-ROM, CD-R, CD-RW, and Photo CD. Magnetic storage devices use magnetic media to store data while optical storage utilizes lasers to read and write digital information to discs.

1. Storage devices used in computers
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2. Objective:
On completion of this period, you would be
able to know:
The storage devices used in computers.
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3. Recap:
 Why Cache Memory is used ?
Cache Memory is used to increase the
speed of the computer.
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4. Prerequisites:
What is storage media?
The physical components or materials on which
data is stored called storage media.
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5. What are storage devices ?
 The hardware components that write data to,
and read it from, storage media are called
storage devices.
 Example: floppy disk
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6. Categories of storage technology
The two main categories of storage technology
used today are
Magnetic storage
Optical storage
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7. Magnetic storage
The primary types of magnetic storage are as
follows:
 Diskettes
 Hard disks (both fixed and removable)
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8. Magnetic storage (contd...)
 High capacity floppy disks
 Disk cartridges
 Magnetic tape
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9. Magnetic storage (Contd...)
 Magnetic storage devices work by polarizing tiny
pieces of iron on the magnetic medium.
 Read/write heads contain electromagnets that
create magnetic charges on the medium.
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10. Diskettes
 Diskette drives, also known as floppy disk
drives, read & write to diskettes.
 Diskettes are used most often to transfer files
between computers
as a means for distributing software
as a backup medium.
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11. Diskettes (contd)
 Diskettes are available in two sizes : 5.25 inch
and 3.5 inch.
 The 5.25 inch diskette is rarely used today.
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12. Hard disks
Hard disk can store more data than diskettes
because of
 their higher density media
 faster rotational speed and
 the tiny distance between the read/write
head & the disk surface.
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13. High capacity floppy disk
 High capacity floppy disk are becoming a
popular add- on for many computers.
 They offer capacities up to 250MB and the same
portability as standard floppy disks.
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14. Disk cartridges
 A disk in plastic case that is inserted into or
removed from the drive. The disk and the case
are often called disk cartridge.
 Disk cartridges are like small removable hard
disks and can store up to 2GB.
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15. Magnetic tape
 Magnetic tape system offer slow data access.
 Because of their large capacities and low cost,
they are a popular backup medium.
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16. Optical storage
The primary types of optical storage are as follows:
 Compact Disk Read-Only Memory (CD - ROM).
 Digital Video Disk Read-Only Memory (DVD -
ROM).
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17. Optical storage (contd)
 CD - Recordable (CD-R) .
 CD - Rewritable (CD - RW).
 Photo CD.
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18. CD-ROM
 CD-ROM uses the same technology as a music
CD does; a laser reads lands and pits on the
surface of the disk.
 Standard CD-ROM disks can store up to 650
MB.
 Once data is written to the disk, it cannot be
changed.
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19. Digital Video Disk Read-Only Memory
(DVD-ROM).
 DVD-ROM technology is a variation on standard
CD-ROM.
 DVD-ROM is a high density medium capable of
storing a full length movie on a single disk
 DVD-ROM offers capacities up to 17 GB.
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20. CD - Recordable (CD-R) .
 CD-Recordable drive can be attached to a
computer as a regular peripheral device.
 CD-R allows you to create your own CD-ROM
disks that can be read by any CD-ROM drive.
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21. CD - Recordable (CD-R) (contd).
 After the information has been written into a part
of the CD, that information cannot be changed.
 With most CD-R drives, however, you can
continue to record information to other parts of
the disk until it is full.
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22. CD - Rewritable (CD-RW).
 CD-Rewritable drives , however, users can write
and overwrite data onto compact disks.
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23. Photo CD
 One popular form of recordable CD is Photo CD.
 Developed for storing digitized photographic
images on a CD
 Many film developing devices now have photo
CD drives that can store your photos and put
them on a CD.
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24. Photo CD (contd..)
 With a photo CD, you can continue to add
images until the disk is full.
 Written images cannot be erased or changed.
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25. Summary:
In this class, you have learnt about
 different storage devices used in computers.
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26. Frequently Asked Questions
1. List the storage devices.?
2. Explain the primary magnetic storage devices
used in computers?
3. Explain the primary optical storage devices?
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27. Quiz:
1. Storage device which offer slow data access.
a. Magnetic tape
b. diskettes
Answer: a
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28. Contd..
2. CD developed for storing digitized photographic
images is
a. CD-R
b. Photo CD
Answer: b
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29. Contd..
3. The high density medium capable of storing a
full length movie on a single disk is
a. DVD-ROM
b. CD-RW
Answer: a
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