Storage Devices

Storage Devices

1. Lectureno:10
IntroductiontoComputer/Computer
Education
Mr.MuhammadMoazzam
MPhilPublicHealth
BScBioMedical
UniversityoftheLahore

2. StorageDevices

3. StorageDevices
•Astoragedeviceisusedinthecomputersto
storethedata.
•Another way to define, Astorage deviceis
any hardwarecapable of holding information
either temporarily or permanently.
•Providesoneofthecorefunctionsofthe
moderncomputer.

4. Why is storage needed in a
computer?
•Without a storage device, a computer cannot
saveor remember any settings or information and
would be considered a dumb terminal
•Although a computer can run with no storage
device, it would only be able to view information,
unless it was connected to another computer that
had storage capabilities
•Even a task, such as browsing the Internet,
requires information to be stored on your
computer

5. A computer only understands
the numbers 0or 1, or whether
a switch is onor off.
We call those 1s and 0s ‘bits’ –
binary digits.
A byte(made up of 8 bits) is
enough computer memory to store
a single character of data (e.g. the
letter F).
The computer uses a code to understand what each bit
pattern means.
Using the ASCIIcode, for instance, the letter F is 70 and has
a bit pattern of 01000110.
Bits and bytes

6. ASCII for Capital
Letters
65A 78N
66B 79O
67C 80P
68D 81Q
69E 82R
70F 83S
71G 84T
72H 85U
73 I 86V
74J 87W
75K 88X
76L 89Y
77M 90Z
American Standard Code for
Information Interchange is a
code which represents English
characters as numbers. Each
letter is assigned a number. For
example, A = 65.
Most computers use ASCII
codes. This makes it possible to
transfer data from one computer
to another by changing the ASCII
code into a binary pattern.
ASCII

7. All computer data is stored in binary form.
This not only includes text, but images, sounds and movies
as well.
The more complex the data, the more memory is used to
store it.
Binary patterns
This does not take up as
much memory…
…as this.

8. The amount of data storedis measured in kilobytes(KB).
Confusingly, 1KBis actually 1,024 bytes (2
10
), not 1,000 as
you might expect, but most people think in multiples of
1,000.
1 bytes= 8bits
1megabyte(MB) =1,024 KB(2
20
)
1 gigabyte(GB) =1,024 MB (2
30
)
1 terabyte(TB) =1,024GB(2
40
).
Data storage

9. CSCA0101 ComputingBasics
StorageDevices
Types ofStorage
There are twotype ofstorage:
•Primary Storage
•SecondaryStorage
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10. CSCA0101 ComputingBasics
1
0
StorageDevices
PrimaryStorage
•Also known as mainmemory.
•Primary storage is a storage location that holds memory
for short periods of times while the computer is on.
•TheCPUcontinuouslyreadsinstructionsstored
there and executes them asrequired.
•Example:
–RAM
–ROM

11. Computers store temporary data in the RAM(Random Access Memory).
These could be operating instructions, loose bits of data or content from
programs that are running.
The contents of RAM are constantly rewritten as the data is
processed.
When the computer is switched off,
all the data is clearedfrom the
RAM.
This type of memory is called
volatilebecause it only storesthe
data whilst the computer is
switched on.
RAM sticks are found on the motherboard.
Random Access Memory (RAM)

12. CSCA0101 ComputingBasics
StorageDevices
There are two types ofRAM:
1-DRAM (Dynamic Random AccessMemory)
2-SRAM (Static Random AccessMemory)
StaticRAM DynamicRAM
•Faster
•Moreexpensive
•More powerconsumption
•does not need to berefreshed
•Slower
•Lessexpensive
•Less powerconsumption
•needs to be refreshed
thousandsof times per
second

13. When a computer is first switched on, it needs to load up the BIOS
(Basic Input/output System) and basic instructions for the
hardware.
These are stored in ROM(Read Only Memory).
Read Only Memory (ROM) is
both a non-volatileand
permanent form of primary
storage.
Data stored in ROM remains there
even when the computer is
switched off.
ROM can be found on the
motherboard.
Read Only Memory (ROM)

15. How memory works?
•The main memory is connected to the CPU through data
bus.
•When CPU wants to read data from the memory it first
place request on the control bus, and also place the
address of the bytes or word needed on the address bus.
•The memory unit reads the command and the address and
puts the required data on the data bus.
•The CPU then read this data from the data bus.
•This is similar for writing data.

16. Memory works

17. CSCA0101 ComputingBasics
17
StorageDevices
SecondaryStorage
•Secondary storage is a storage medium that holds
information until it is deleted or overwritten regardless if
the computer has power
•It is not directly accessible by theCPU.
•Computerusuallyusesitsinput/outputchannelstoaccess
secondarystorageandtransfersthedesireddatausing
intermediateareainprimarystorage.
•Example:
–Hard disk

18. CSCA0101 ComputingBasics
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StorageDevices
SecondaryStorage
HardDisk
•The hard disk drive is the main, and usually largest, data
storage device in acomputer.
•Itcanstoreanywherefrom160gigabytesto2
terabytes.
•Hard disk speed is the speed at whichcontent can
be read and written on a harddisk.
•Aharddiskunitcomeswithasetrotationspeed
varying from 4500 to 7200rpm.
•Disk access time is measured inmilliseconds.

19. CSCA0101 ComputingBasics
StorageDevices
SecondaryStorage
HardDisk
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20. Types of Hard Disk
There are two types of Hard Disk
•Internal Hard disk
•External Hard disk

21. CSCA0101 ComputingBasics
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StorageDevices
SecondaryStorage
HardDisk
Internal Harddisk External Harddisk
Portability No Yes
Price Lessexpensive Moreexpensive
Speed Fast Slow
Size Big Small

22. CSCA0101 ComputingBasics
StorageDevices
SecondaryStorage
HardDisk
Internal Harddisk
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External Harddisk

23. CSCA0101 ComputingBasics
StorageDevices
MagneticTape
•Amagneticallycoated
plasticonwhichdata
stripof
canbe
encoded.
•Tapesforcomputersaresimilarto
tapesusedtostoremusic.
•Tapeismuchlessexpensivethan
otherstoragemediumsbutcommonly
amuchslowersolutionthatis
commonlyusedforbackup.
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24. CSCA0101 ComputingBasics
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StorageDevices
FloppyDisk
•A soft magneticdisk.
•Floppy disks areportable.
•Floppydisksareslowertoaccessthanharddisksand
havelessstoragecapacity,buttheyaremuchless
expensive.
•Can store data up to1.44MB.
•Two common sizes: 5 ¼” and 3½”.

25. CSCA0101 ComputingBasics
StorageDevices
FloppyDisk
5 ¼ inch FloppyDisk
25
3 ½ inch FloppyDisk

26. StorageDevices
•FloppyDisk

27. Magnetic card
•Amagnetic cardis a card that contains either
amagnetic stripor a magnetic object in the
card, encoded with digital data.
•A magnetic card may contain information
about an individual, such as available credit on
a credit card or pass codes for entering secure
buildings. It's usually the size of a business
card or credit card.

28. Magnetic card
•The picture is an example of a magnetic card
being swiped through a magnetic card reader.

29. CSCA0101 ComputingBasics
29
StorageDevices
OpticalDisc
•Opticaldiscisanystoragemediathatholdscontentin
digitalformatandisreadusingalaserassemblyis
consideredopticalmedia.
•The most common types of optical media are
–Compact Disc (CD)
–Digital Versatile Disc(DVD)

30. StorageDevices

31. Flash Memory
•Flash Memoryhas replaced most magnetic and
optical media as it becomes cheaper because it
is the more efficient and reliable solution.

32. Flash drive
•Alternatively referred to as aUSB flash
drive,data stick,pen drive,memory
unit,keychain driveandthumb drive, ajump
driveis a portablestorage device.
•It is often the size of a human thumb (hence the
name), and connects to a computer via
aUSBport. Flash drives are an easy way
tostoreandtransferinformation between
computers and range in sizes from 2GBto 1TB.

33. Flash drive

34. CSCA0101 ComputingBasics
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StorageDevices
MemoryCard
•Anelectronicflashmemorystoragediskcommonly
usedinconsumerelectronicdevicessuchasdigital
cameras,MP3players,mobilephones,andother
smallportabledevices.
•Memorycardsareusuallyreadbyconnectingthe
devicecontainingthecardtoyourcomputer,orby
usingaUSBcardreader.

35. CSCA0101 ComputingBasics
StorageDevices
MemoryCard
Secure Digital card(SD) MiniSD CompactFlash MemoryStick
MultiMediacard XD-Picturecard
Memory cardreader
35

36. Online and cloud
Storing data online and in cloud storage is
becoming popular as people need to access their
data from more than one device.
•Cloud storage
•Network media

37. Cloud computing
•Cloud computingis a term used to describe
services provided over a network by a
collection of remote servers.
•This abstract "cloud" of computers provides
massive, distributed storage and processing
power, which can be accessed by any Internet-
connected device running a web browser.

38. How do you access cloud
computing?
•Cloud computing is accessed through
anapplication(e.g., Dropboxapp) on your
computer, smartphone, or tablet or
awebsitethat accesses the cloud through
yourbrowser

39. Network Media
•Network mediais any audio, video, images or
text, used on a computer network, like
theInternet

40. Why so many different storage
devices?
•As computers advance, the technologies used to
store data do too, right along with higher
requirements for storage space. Because people
need more and more space, want it faster, cheaper,
and want to take it with them, new technologies
have to be invented.
•When new storage devices are designed, as
people upgrade to those new devices, the older
devices are no longer needed and stop being used

41. Why so many different storage
devices?
•For example, when punch cards were first used in
early computers, the magnetic media used for
floppy disks was not available.
•After floppy diskettes were released, they were
replaced by CD-ROM drives, which were
replaced by DVD drives, which have been
replaced by flash drives.
•The firsthard disk drivefrom IBM cost $50,000,
was only 5 MB, big, and cumbersome.

42. Why so many different storage
devices?
•Today, we havesmartphonesthat have
hundreds of times the capacity at a much
smaller price that we can carry in our pocket.
•Each advancement of storage devices gives a
computer the ability to store more data, as well
as save and access data faster