Input devices

Keyboard
1. QWERTY Layout
  1. alphanumeric keys
    Anotações:
    - letters and numbers
  2. punctuation keys
    Anotações:
    - comma, period, semicolon etc.
  3. special keys
    Anotações:
    - function keys, control keys, arrow keys, Caps Lock key etc.
  4. data can be typed very quickly
  5. disadvantage : easy to make mistakes
2. Concept keyboard
  1. Faster but limited
  2. found in shops and restaurants
  3. symbol/picture represent a piece of data
3. Braille
  1. system of sequences of dots that can be read by touch
  2. for visually impared people
  3. Allows to enter text in Braille and also read text
4. Touch sensitive screen
  1. used in info centers or ATM machines, smartphones
  2. easy to use
  3. more expensive
  4. can be innacurate
  5. Both: Input and Output
Pointing devices
1. mouse
  1. ball under mouse moves - cursor moves
    Anotações:
    - Sensors measure the movement of the ball in 2 directions and computer works out the direcion and distance the mouse has travelled
    1. Ball can get dirty and stuck if not cleaned regularly
  2. used to select and move around items displayed on screen
  3. Easier to select items by slicking icons
  4. Easier to move around than using arrow keys
2. tracker ball
  1. not very accurate and quick
  2. used by people with unsteady hands
  3. rolls ball to control cursor movement
  4. like an 'upside down' mouse - ball on top
3. touch pad
  1. used instead of mouse on laptops
  2. movement of fingers on touchpad mirrored by cursor on screen
  3. hard to use if you are used to a mouse
  4. takes up less space
Joystick
1. used for games
2. joystick is fixed to the base
3. allow movement of an object around a screen in any direction
4. have special buttons e.g 'fire' or 'jump'
Scanners
1. used to transfer 2D images into a file on a computer
  1. picture scanned and converted into digital data
    Anotações:
    - Scanner shines light onto paper document and measures amount of light reflected back.
    1. can save time of retyping large amounts of text
  2. files can be manipulaed and edited easily and quickly
  3. large files can take up a lot of memory
2. Flat bed
  1. useful for flat documents e.g page of a book
3. Hand held
  1. can be moved around oddly shaped objects or long documents
Digital cameras
1. DPI (dots per inch) is called resolution
2. pictures stored on smart cards and can be transferred directly onto computer
  1. images can be edited on computer, be used for documents/presentations etc.
  2. can be sent as an attachment via email
3. Advantages: no expensive developing costs, no film needed
4. Disadvantages: more expensive than ordinary cameras; high-resolution images use lots of memory and battery power
Microphones
1. detects sound and inputs it into computer
  1. converts it into digital format
    1. can add spoken messages or music with presentations or emails
2. 1.Person speaks into microphone. 2.Speech recognition software converts what is said into text
3. people with disabilities can benefit from use of microphone
4. Disadvantages: 1) Should be no background noise 2) sound recorded using microphone is often not very good
Magnetic stripe reader
1. Dark stripe at the back of a plastic card contains data
  1. e.g Bank card contains sort code and account number
    1. data can be read by ATMs, cash registers and banks
  2. Data is read when card is swiped through a magnetic stripe reader
    Anotações:
    - Sends information to computer bank. Checks if there is sufficient amount available for transaction. If no - card payment is declined. If yes - payment goes through. Money is transferred from customer's bank account onto shop's account.
2. Advantages: 1) data is not visible to people 2) card cheap to produce 3) quick to read, coneinient to pay for goods
3. Disadvantage: 1) magnetic stripe might get damaged 2) card can be stolen
Graphic pads
1. like a pen and paper
  1. made of a touch-sensitive membrane and a stylus
    1. Translates the movement into digital signal which is sent to a computer
2. can be used by designers or illustrators to create accurate detailed drawings
MIDI
1. Musical Instrument Digital Inerface
  1. used to edit and develop music by mixing with other sounds which are input from microphone
  2. sound can be altered: speed up/ slowed down
  3. Knowledge of software and music required
2. Variety of musical instruments used: guitar, keyboard, drums etc.
  1. send messages via MIDI and get converted to digital data
    1. can be sent back to instrument to reproduce signal
Barcode reader
1. Hand held device with a laser beam which can scan a barcode
  1. the reflected light is transferred into digital data that is interpreted by the computer to identify the product
    1. Product is found in the database and price is displayed
      1. advantage: price changes only need to be made to a database not every single product
2. uses visible red light
3. Barcodes are used on product packages in a shop

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	Criado por mezhievaseda mais de 11 anos atrás