INFORMATION TECHNOLOGY
DEFINITIONS
Computer:
A computer is an electronic machine that receives input,
stores and automatically processes data, and provides
output in a useful format.
Data:
Data is raw & unorganized facts and figures that need to be
processed.
DEFINITIONS
Information:
When data is processed and organized so as to make it
useful and meaningful, it is called Information.
Information Technology:
A term that refers to both the hardware and software that
is used to store, retrieve and manipulate information.
ADVANTAGES OF COMPUTERS
Speed and accuracy of calculations and processing.
Save huge amounts of data.
Economic in cost and time.
Network communications.
COMPUTER GENERATIONS
1
st
Generation (Vacuum Tubes)
Very huge in size
.
Very expensive.
Very low processing speed.
Relied on the machine
language to perform operations.
COMPUTER GENERATIONS
2
nd
Generation (Transistors)
Smaller
Faster
Cheaper
COMPUTER GENERATIONS
3
rd
Generation (Integrated Circuits)
The speed and the efficiency of the computers were
increased.
COMPUTER GENERATIONS
4
th
Generation (Present Microprocessor)
Most powerful.
Can be linked together to form networks.
Fastest and most efficient.
TYPES OF COMPUTER
SUPER COMPUTER
Biggest and most powerful.
Rare because of their cost and size.
Used by companies like NASA.
MAINFRAME COMPUTER
Great processing speed and data storage.
Often connected to many individual PCs with limited
processing capabilities called dumb terminals.
Used in Banks, Airlines etc.
MINICOMPUTER
A Midsize Computer not very common now.
Minimized in size and power.
Can connect up to
200
users at a time.
MICROCOMPUTER
Also called
Personal
Computer
(PC)
Small
enough to fit on top of a desk, which can be
used by one user at a time
.
Used in homes, schools
etc.
WORKSTATION COMPUTER
High
-
end
microcomputer.
Used by one person at a time.
Commonly connected to a
local area network.
CONTROL COMPUTER
Used for controlling operations in industrial, medical
devices and travel media like planes and cars
Also used to alert in any dangerous case.
PARTS OF A PERSONAL
COMPUTER
Computer
Hardware
Software
DEFINITIONS
Hardware:
The physical parts of a computer which you can see
and touch.
Hardware
1
) Input
Devices
2
) Output
Devices
3
) Processing
Unit
4
) Memory
Unit
5
) Storage
Devices
HARDWARE
1
) Input Devices:
Devices used to
translate the data into a form that the
computer can process.
a) Keyboard
It
is
a
board
containing
the
keys
of
letters,
numbers
and
some
functions
which
allows
you
to
type
information
into
the
computer
.
b) Mouse
A
small
hand
-
held
device
used
to
point,
select,
click
on
items
and
to
drag
and
drop
items
from
one
place
to
another
.
c) Scanner
It allows you to scan pictures, text and images and
save it to your computer in a digital form.
d) Bar Code Reader
Photoelectric scanners that translate the bar code
symbols into digital form.
e) Joystick
Small
hand
-
lever
that
can
be
moved
in
any
directions
to
control
movement
on
the
screen
.
It
can
be
used
for
playing
games
.
HARDWARE
2
) Output Devices:
Devices used to
translate the processed information into a
form that humans can understand.
a) Monitor (computer screen)
It
displays
the
text,
information
and
pictures
.
They
are
different
in
(Size
and
Resolution)
b) Printer
It produces a hard copy of the material you are
working on.
Types:
1
) Laser Printer
2
) Ink
-
jet Printers
c) Plotters
It is similar to a printer but allows you to print larger
images.
d) Speakers / Headphone
They
are used to output voice from a computer
NOTE:
Some devices can be used as both Input and output
devices at the same time such as
Touch Screen:
It receives input from the touch of a finger.
HARDWARE
3
) Processing unit
(CENTRAL PROCESSING UNIT)
The most important part of a computer system.
Referred to as the brain of the computer.
Determines the speed of computer which is
measured in
MHz
or
GHz
.
1
GHz=
1000
MHz
CPU (Central Processing Unit )
CPU consists of:
CU (Control Unit):
It tells the computer
system how to carry out program instructions from
the memory. It controls and coordinates all activities
of the computer.
ALU (Arithmetic and Logic Unit):
It
performs mathematical and logical operations
HARDWARE
4
) Memory unit
Memory
RAM
ROM
RAM (Random Access Memory)
The operating system is loaded into the RAM when
you switch on your computer.
Used to store applications that you are currently
working with.
It is temporary
(volatile)
.
ROM (Read Only Memory)
It has special programs which are built
-
in when you
buy the computer.
Used to store control programs.
It is permanent
(non
-
volatile)
.
HARDWARE
5
)
Storage Devices:
Hardware devices which
are used to record and store data.
1
) INTERNAL STORAGE
HARD DISK
It is the most important storage media in the
computer.
It stores operating system and programs.
2
) EXTERNAL STORAGE
A compact and easy
-
to
-
use device for transferring data
between computers.
a) Flash Memory
b) CD (Compact Disk)
An
optical
disk
which
uses
laser
to
read
information
.
It
has
750
MB
capacity
.
c) DVD (Digital Versatile Disk)
A
high
-
density
video
disc
that
stores
large
amounts
of
data,
especially
high
-
resolution
audio
-
visual
material
like
movies,
encyclopedia
etc
.
The
capacity
is
up
to
17
GB
.
DISK AND MEMORY CAPACITY
The first level of storage is called
bit
(the bit is
referred to a binary number
0
or
1
).
Byte
=
8
bits.
Kilo Byte (KB)
=
1024
bytes.
Mega Byte (MB)
=
1024
KB.
Giga Byte (GB)
=
1024
MB.
Tera
Byte (TB)
=
1024
GB.
COMPUTER PERFORMANCE
1.
The speed of the processor.
2.
The capacity of RAM.
3.
The capacity and the speed of the Hard
disk.
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