Chapter 2
HAEDWAER
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COMPONENTS OF A COMPUTER
There are mainly 2 types of COMPUTER
COMPONENTS :1-Hardware.
2-Software.
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Question
*What is the difference between a calculator and
a computer?
The definitional difference between the two is
that a computer can be reprogrammed to
perform a multitude of different tasks whereas
a calculator is engineered only for one specific
set of tasks.
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Hardware
Hardware: The hardware consists of all devices of the
Computer that you can see and touch.
Hardware types are:
1) Input Devices i.e. the keyboard and mouse .
2) Output Devices i.e. monitor and printer
3) Processing Devices or CPU.
4) Storage Devices i.e. memory , hard disk and flash
memory
5) Others Devices i.e. modems and cards.
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Hardware
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1- Input Devices
- Input devices : are hardware used to translate
words, sounds, images, and actions that people
understand into a form that the computer can
understand .
- Inputs is referred to Soft Copy
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Examples of Input Devices
1-Keyboards
2-Pointing devices (Mouse).
3-Scanning devices
4- Microphone.
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Keyboard
- Keyboards: It is used to type data into the computer or
input data.
- Keyboards come in a variety of designs.
- The most common types are:
1-Traditional keyboards.
.2-Flexible keyboards
3-Wireless keyboards
… etc
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Keyboard Entry
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Keyboard Entry
1) Numeric keypad : used to enter numbers and
arithmetic symbols.
2) Function keys : provides shortcuts to specific tasks.
3) Escape key : cancels a selection or a procedure.
4) Windows key : displays the start menu.
5) Space bar : enters blank spaces between characters.
6) Navigation keys : controls the cursor or insertion
point on the screen.
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Pointing Devices
- Pointing Devices provide a comfortable interface
that creates machine-readable data that can go
directly to the CPU.
- Examples of Pointing devices : mouse, joystick
,touch screen, light pen …..etc.
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Mouse
- Mouse : controls a pointer that is displayed on the
monitor.
- Generally if the mouse has two buttons the left one is
used to select objects and text and the right one is
used to access menus.
- Similar devices to Mouse : Track ball ,Touch pads
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Mouse
• A mouse incorporates a mouse pointer which
usually appears in the shape of an arrow.
• Some mouse are also equipped with a wheel
button that can be rotated to scroll through
information.
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Other Pointing Devices
1- Joystick
Joystick – input for computer games.
2- Touch Screen
a kind of monitor with a clear plastic outer layer Easy to
use.
3- Light Pen
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Scanning Devices
- Scanners move across text and images .
- Scanning devices : convert scanned data into a form
the system unit can process.
- Examples of scanning device :
Flatbed Scanner, bar code reader.
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Image Capturing Devices
1) Digital cameras
- Images recorded digitally on a disk
2) Digital video camera
- Records motion digitally
3) WebCams
- Broadcast images & videos over the Internet
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2- Output devices
- Output devices : are any hardware used to provide or to
create output.
- They translate information that has been processed by the
system unit into a form that humans can understand.
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Output devices
- The most widely used output devices are :
1- monitors.
2- printer.
3- speakers and headphones.
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Monitors
- Known as screens or display screens
- A monitor takes information and display the screen for you
to look at.
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Monitors
• Standards indicate screen quality (resolution). Some monitors are used on
the desktop, others are portable.
• Features – most important is clarity.
• Resolution – one of the most important features; images are formed on a
monitor by a series of dots or pixels (picture elements).
• Dot (pixel) pitch– the distance between each pixel; most newer monitors
have a dot pitch of 31 mm (31/100th of a millimeter) or less.
• Refresh rate – indicates how often a displayed image is updated or
redrawn on the monitor; most monitors operate at a rate of 75 hertz
which means that the monitor is redrawn 75 times each second; flickering
indicates that the monitor rates are lower than 75 hertz.
• Size – or viewable size is measured by the diagonal length of a monitor’s
viewing area.
• Common sizes are 15, 17, 19, and 21 inches.
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Types of Monitors
1- Cathode-ray tube (CRT) monitors
2- Flat-panel monitors or Liquid Crystal Display (LCD)
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Printers
• Printer : Translates information that has been
processed by the system unit and present the
information on paper
• Output referred to as hard copy.
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Printers
• Printers translate information that has been processed by the system unit
and present the information on paper.
• Output is called hard copy.
• Features:
 Resolution – measures the clarity of images produced, measured in dotsper-inch (dpi). Most printers use an average of 1200 dpi; the higher the
dpi, the better the quality of image produced
 Color capability – more expensive to print in color; usually have the option
to print in either color or b/w.
 Speed – measured in the number of pages printed per minute, 15-19
pages per minute is the average for a single color page (black); 13-15
pages per minute for color.
 Memory – used to store printing instructions and documents waiting to be
printed.
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Types of Printers :
1- Ink-jet printer
2- Laser printer
3- Thermal printer
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speakers and headphones
• speakers and headphones :
translate audio information from the computer
into sounds that people can understand .
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Combination input and output devices
*Fax machines
*USB Drives.
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Assignment
Compare between the three Printers :
1- Ink-jet printer
2- Laser printer
3- Thermal printer
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