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Input devices

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Input devices• Are used to get raw data into the

computer so that it can be processed• Include common input devices such

as keyboard, mouse, joystick, etc.• Include specialist input devices such

as bar code reader, magnetic stripe reader, etc.

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Input devices: Keyboards• Most popular method

for entering text• Slow• Prone to human error• Need typing skills• Can lead to repetitive

strain injury (RSI)• Can be specialist

(e.g., Braille keyboard)

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Input devices: Numeric keypad

• Used to enter just numeric data

• Used in ATMs to enter PINs and amounts

• Used in chip and PIN machines

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Pointing devicesPointing devices include:• Mouse• Touchpad• Trackerball

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Joysticks• Used mainly for

computer games• Stick moves on-

screen like a mouse• Buttons are used to

make selections

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Microphones• Used to enter

voice, sounds, live music, etc.

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Remote controls• Issue instructions to

enable devices to be controlled

• Sometimes allow characters to be typed

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Web cams• Digital cameras that

can take both still and video images

• Used for simple videoconferencing

• Picture quality can be poor

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Touch screens• User touches buttons

and icons on the screen to make selections

• Used in many mobile devices such as phones, MP3 players, tablet computers

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Digital cameras• Many can take both

still and video images• Storage is a memory

card• Many mobile phones

and computers can take video and still images

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Scanners• Used to scan in old

photographs• Can digitize hard

copy• Can use with optical

character recognition software to input text

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More specialized input devices

• Bar code readers – used for recording goods in supermarkets, tracking library books, luggage handling in airports, etc.

• Chip and pin readers – used in stores and restaurants, etc., to read information off credit/debit cards

• Magnetic stripe readers – used to read credit card details (where there is no chip and PIN), loyalty card details, etc.

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Bar code readers• A code is stored as a series of

light and dark bars• Uses a scanner to read the

bars• Used on items in stores,

parcels, luggage handling at airports, etc.

• Fast to read • Accurate• Can be read at a distance

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Magnetic stripe reader• Read data stored on

magnetic stripes by swiping • Used for reading credit card

data where a chip and PIN reader is not available

• Used for pre-payment cards

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Chip and PIN• Used to capture

credit/debit card details

• Details are encrypted on a chip

• User has to enter a PIN that only they know

• The PIN is checked and proves the user is authentic

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Optical character reader• Able to read typed or

handwritten text• Image of text is

scanned or input by writing on a tablet computer

• Special recognition software recognizes individual characters

• Text can then be used with other software

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Optical mark recognition (OMR)

• Automatically reads marks made on a form

• Forms are read/scanned at high speed

• Readers are relatively cheap

• Can be high reject rate owing to people not filling in the form correctly

• If forms are folded they cannot be read

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Graphics tablets• Are flat boards or

tablets• Draw or write on

them using a stylus

• Ideal for inputting hand-drawn drawings

• Used in CAD

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Sensors• Measure physical

quantities (e.g. temperature, pressure, humidity, etc.)

• Send signals to be processed by the computer

• Data can then be used to control devices