Post on 15-Jul-2015
transcript
The data or instructions you type into the
computer are called input Input devices used to get data into a system.
Get data into a system as accurately, least
amount of time.
It’s a cheap device.
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Keyboard
Mouse
Tracker ball
Touch sensitive pad
Joystick
Light pen
Touch screen
Graphics tablets
Magnetic Strip Reader
Bar Code reader
Digital cameras
Web Cameras
OCR
MICR
OMR
Punched Card
Kimball tag
Voice recognition
Microphone
EPOS
EFTPOS
Video digitiser
Scanner
Touch Phone Telephone
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Keyboard is the oldest and most familiar of all input devices
Keyboard are intelligent devices and contain their own chips.
The microprocessor scans the keyboard hundreds of second to see if a key has been pressed .
The CPU translate that key and convert into ASCII code.
A standard keyboard called QWERTY keyboard.
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New keyboards, called concept
keyboards, have been developed
for ergonomics
The goal of this keyboard is to
provide comfort and safety.
The user who spends a lot of
time in typing may experience
repetitive injuries of wrist and
hand.
Higher typing speeds can be
achieved.
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That requires no wires
It is also called wireless keyboards.
It transmits data using wireless technology
like radio waves or light waves
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These keyboards make it easy for blind users
to input data into a computer
There are also keyboards with large coloured
keys that are easier to see.
Each key is about one inch square.
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Most computers come with a keyboard
supplied
People are used to using keyboards to enter
data, they need very little training
A skilled typist can enter data very quickly
Specialist keyboards are available e.g.
ergonomic, gaming keyboards
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It is easy to make mistakes when typing in data
If you can't touch type, it can be time consuming to enter data
Keyboards are not suitable for creating diagrams
Disabled people often find keyboards difficult to use
Excessive use can lead to R.S.I.
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That translate its movement on the desktop
into digital information.
Moving the mouse produces movement of
cursor or the pointer on the screen.
The mouse is also provided with buttons to
press.
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Movement of ball bearing is used to produce
electrical signal.
Small lights under the mouse are reflected
on the photoelectric cells.
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To select options from a menu or form a set
of icons
To position the cursor when editing text or
using a design package.
To draw shapes.
It selects a position on the screen more
quickly than is possible with a keyboard.
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Is similar to tracker ball.
Is a device which enables the user to control movement on the screen by a small lever.
The lever can be moved in any direction.
Some joysticks give more control on the screen.
Uses
Controlling objects in computer games
Producing graphics
Scanners in hospitals
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Is a pen shaped device, held in the hand which can detect the presence or absence of light
It is connected by the cable to a recording device or to a computer or computer terminal.
Electrical signals are sent along the cable indicating whether or not light of sufficient intensity is being sensed.
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To detect bar codes
To indicate a point on the screen
It removes the need to type or write.
It is faster than typing.
Disadvantage:
It can only record the presence or absence of light.
It only works with software written for it.
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Is also known as digitizing or digitizing pad.
The digitize data means to convert it from analog form to digital.
A design is put on the board and its shape is traced out with the stylus.
Electrical signals sent to the computer record the position of the stylus.
Encoding the picture into binary form
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It can be used to digitize drawings with great
accuracy.
Reproducing drawings and designs
Producing layouts of printed circuit boards.
Digitizer Maps.
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Is a small, flat surface over which the
user moves his finger.
The movement of the finger moves the
cursor on the screen.
A touch pad also has one or more buttons
near it .
These buttons like mouse buttons.
Touch pads are commonly used with
notebook computers
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Is a video display screen that receives input
from the touch of finger
Examples
ATM
Petrol Pumps
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Is a short length of magnetic tape stuck on the surface of a tag, card or document.
On plastic tags or cards the strip is sealed in.
Tags with stripes identify the item they are attached to.
Examples:On credit card On bank cardsA phone Card Cash issue Terminals
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It is simple to produce.
It is not easily damaged.
It stores a large no of characters.
Disadvantages
The data can be changed or erased by
magnetic field.
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Is set of parallel printed lines of differing thickness, which represent a number.
The number represented by the bars is also printed above or below the bar code.
When bar code are used on shop goods, the number coded identifies the product and have following information
1. Country of region
2. Manufacturer
3. An item number for the product.
Examples:
Used in Barcodes
Library System
Warehouse stock
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Printed easily
The type of item or its price does not have to be repeatedly written down or typed.
Disadvantages:
bar codes cannot be changed and thus there are unsuitable prices.
Bar codes only be read by machine.
Only numbers can be coded in this way.
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Is a technology that reads typewritten ,
computer printed or handwritten
documents.
It translate the image into a form that
can be recognized by computer.
OCR devices read printed characters using
OCR font.
An OCR device determines the shapes of
characters by detecting patterns of light
and dark.
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In department stores
To scan financial documents such as company
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It is also called mark sensing device.
It uses light to scan input data to convert it into electrical/digital signal.
The signals are then sent to the computer for further processing.
Examples
Voting ballot
Multiple choice answer sheet marking
Enrollment forms
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In OMR there is typing involve so errors and takes time is less
Reduces the cost of inputting large amount of data
The method is useful when results of the test are needed very quickly
Disadvantages
Readers are very expansive
Only certain fonts are acceptable.
There is high rejection rate
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Characters are printed using
an ink containing iron oxide.
As the document passes into
the reader the ink is
magnetized, so that the
character shapes can then
be recognized electrically.
It is used by banks industry for check processing.
Each check contains MICR characters at the lower
left edge.
These characters represent check number ,bank
number and account number
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Branch codeCheque number Account number
Documents can still be read when folded,
written on
Disadvantages
Readers are very expansive
Only certain fonts are acceptable.
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Contains holes in different positions which
mean something when they are read by a
reader.
Punched cards were the main method of
entering data into computers.
Example:
The clock card which is used to record the
hours a person works so that wages can
be calculated.
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Kimball tags are the small cards with holes
punched in them that you see attached to
clothing in certain shops.
When you buy the goods, one of the tags is
removed and sent for processing to a
computer centre.
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Stock is reordered without any writing or
typing the data.
Disadvantages:
They are small and are easily mislaid.
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Using a microphone human speech is coded
into a sequence of electrical signals.
The computer searches a set of stored
patterns for the sound which has been input
It is now popular for inputting data into word
processing or database packages.
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Useful for handicapped people with limited
movement
No typing or data preparation is necessary.
Disadvantage: Few words can be recognized and the error
rate is high.
Not suitable in noisy places
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Is used for input device for a speech
recognition system.
The voice pattern of user is then converted
into instructions to the operating system or
application software or text.
Uses as voice mail messages
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Are the cash registers which act as the
terminals to a main computer system
Providing customers with itemised bills.
Give useful management information
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Similar to EPOS terminal but some additional
features.
They are able to transfer funds from your
bank account directly to a store’s switch card
called a debit card.
Example:
Switch card
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You can use it instead of a cheque.
Faster method of payment
Money is instantly transferred into its
account.
You can also get cash back using your
debit card.
Disadvantage:
They may be stolen and they are said to
encourage people to spend more money.
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Is the combination of hardware and Software that converts an analogue video signal into a digital signal in computer’s memory
Is used to convert a frame from a video sequence into a picture
Each frame from the video is converted using video digitiser.
It may be played back in any required sequence.
Is also called image grabbing or frame grabbing
Take up a lot of main memory and when stored use a large amount of disk space
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Digitiser pictures Can be printed in a
magazine or document
To make television adverts and to produce
pop videos.
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Read data or information from the source
Source could be written document, a price
tag, a graphics image , or photograph
To scan text or images which manipulated in
some way before being printed
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It is a light sending input device.
The scanner image depend upon resolution
Image will be sharper if the scanner provides high resolution
it provide OCR Software
Different types of Optical Scanner are
Flatbed Scanner
Sheetfed Scanner
Handheld Scanner
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Is used to store, picture in digital form.
Store images using different ways like
floppy disk, memory stick, mini CD ,PC
Card and micro device.
Can be connected to a computer easily
through USB port.
Image resolution for digital camera
measured by megapixels.
Higher resolution photo takes up more
memory .
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No film is needed
No expensive developing costs
Pictures are in digital form so it can easily
sent over the internet
You can adjust the size of image
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Is simply a digital camera that is used to capture still images and video images
These images can then be transmitted to a computer where they are stored in graphics format
Pictures can be used on the websites
Camera placed on top the screen such a system allow video conferencing
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Advertising
Checking on children in nurseries
Checking on the weather on the other part of
the world
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Output device provide results in a suitable
form after data processing.
Output devices are used to get data out of a
system.
They should be able to do this as accurately
and quickly as possible, and with the
minimum of human intervention.
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Visual devices (including Visual Display Units
[VDUs], screens, and monitors)
Hard copy devices (including ink jet printer, laser
printers, dot-matrix printers, and plotters)
Sound devices
Computer controlled devices (including robots)
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Most common output deice
It is known as display screen
The output display by monitor is called soft
copy so it is ideal for showing the results
from an enquire where no printed is needed.
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Creates the image on the screen through electronic
beam
This is same type that is use in Television
It consists of one or more guns
These guns generate red ,green and blue (RGB)
colors.
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LCD screens are most often seen on portable or laptop computers
These are used in these applications because they are small and light.
Also used where space is at the premium.
The molecules this substances line up in such a way that the light behind the screens and creates an image.
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Larger than VDU and have greater resolutions
lines on the screen don’t look as through
they are made up of lots of tiny dots.
Are often used in conjunction with light pens
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It prints character ,symbols and graphics on
paper.
Print resolution is commonly measured in
dots per inch (dpi)
Different types of printer are
Impact Printer
Non Impact Printer
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Its act like a typewriter
It prints characters or images by striking a
print hammer or wheel against an inked
ribbon
Dot matrix printer
Line printer
Daisy wheel Printer
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It produces printed images when tiny pins
on a print head strike an inked ribbon
When ribbon pressed against the paper, it
creates dots that they form characters
and graphics
Which can transfer print through layers of
paper.
Able to print multi-part sheet where
It generates lot of noise ,its print quality
is not good
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Is a fast impact printer
It prints a entire line at a time
Its speed is measured in line per minute
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Similar to typewriter
Uses print wheel
A motor rotates the wheel.
Its slower than Dot matrix but better in
quality
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Prints characters and graphics on a piece of
paper without striking the paper.
These printers are faster than impact
printers
Inkjet printer
Laser printer
Thermal printer
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It prints characters and graphics by spraying tiny drops of liquid ink on paper
The print head of an inkjet printer consists of nozzles
It has two cartridges black and whiteThese printers can produce quality text
and graphics in both black and white color
slower than laser printer but faster than dot matrix printer
They can print 1 to 6 pages per minute Cheaper in price Satisfactory in color
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Creates image on the paper by the laser
beam
Also called page printer because they print
complete page at a time
It contain toner
Throws magnetic powder on paper in the
form of microscopic dots
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Print a page at a time so it is fast and it print
pages 10ppm
They produce high quality of text and
graphics
They are quiet in operation compared with
dot matrix
Equipped with paper trays for both the input
and the output papers
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Are more expensive than dot matrix or ink-
jet printer
They are quite large and can take up lot of
disk space
Quite complex so the repair bills can be high
Multi part stationary cannot be used
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Is an output device that is used to produce image quality graphics in variety of colors
Used to create maps, architecture drawings, graphs and charts
A plotter works by drawing lines on paper using pens held in a mechanical arm
It may be in form of
Flatbed Plotter
Drum plotter
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Used to plot or draw images.
It contains pens for drawing images.
The paper is placed on table like surface
Software instructs the pens to move down on
the paper
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Uses a rotating drum or cylinder
The drawing pens are mounted on the drum
The pens move to the left and right as the drum rotates
Advantage of drum plotter is that the length of the plot is almost unlimited
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Visually people find the spoken word from
the computer
Special software is used for this process
In a word processor each letter is typed and
it can hear with headphone.
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An audio device translate audio information
from the computer into sounds that people
can understand
Speakers
Headsets
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Sometimes the output from one computer system can simply be a series of electrical signal
In this case one computer is being used as a terminal and work that is done sent as electrical signals
Electrical signals can be output and used to control all kinds of devices such as
Heating system
Alarms
Robots
Actuators
Computer aided manufacturing (CAM)
Computerised numerical control (CNC)
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