Chapter 2 Input and Output Devices

Chapter 2 Input and Output Devices

1. Keyboards

   • Concept Keyboard
     • Allows the user to decide what each of the symbols mean. Used in places like fast food stores
   • Qwery keyboard
     • Standard keyboard
   • Numeric keypads
     • Used by shoppers to put in their key.

2. Pointing Devices

   • Mice
     • Adv
       • Fast method of input
       • Easy to point and click
     • Dis
       • Easily damaged or broken
       • People with disabilities may find mice hard to use.
       • Overuse of mice can lead to repetitive strain injury
       • Need a flat surface to be moved around on.
   • Touchpads
     • The flat area next to the keyboard. Also allows you to right and left click.
   • Trackerballs
     • Adv
       • Does not need a surface to be moved around on.
       • Not as likely to be damaged as a mouse and can be used by disabled people.
     • Dis
       • Can be difficult to use on apps that require fine control.
   • Joystick
     • Carries out the same task as a mouse as well as other functions such as controlling the movement of a motorised wheelchair.
   • Touch screens
     • Capacitive
       • Adv
         • Much more responsive
       • Dis
         • They can be expensive
       • The are sensitive to your body’s magnetic field.
     • Resistve
       • Adv
         • Relatively inexpensive to produce
         • Can touch it with anything
       • Are sensitive to pressure from your finger. Made with two sheets that when they are touched together changes the resistance between the two surfaces
   • Graphics tablet
     • Adv
       • The ease of drawing and writing
     • Dis
       • They can be expensive
     • A very large touchpad that can sense the pen moving over it.

3. Sensors

   • A device that collects data on its own. Most sensors measure a physical property that can have any value.
   • Adv
     • More reliable than humans
     • It is not possible for humans to go where some reading may need to be taken.
   • Dis
     • They need a power source
   • Types of sensors
     • Temperature sensor
       • Are used in regulating the temperature of a room
       • Controlling heat in greenhouses
     • Pressure sensor
       • A pressure pad is used to detect the amount of pressure on something
     • Light Sensor
       • Measures the amount of light falling on them

4. Inputting images

   • Scanner
     • A device that shines a light at a drawing or a photograph and can interpret the reflected light.
   • OMR
     • Optical Mark Recognition enables data marked by humans to be captured during a scanning process. Eg. P.A.Ts
   • OCR
     • Optical character recognition scans a typewritten document and translates the images into a computer format
   • Digital camera
   • Microphone
     • Microphones can be used to convert sound into data that the computer can handle. A keyboard can be connected to a computer VIA a MIDI interface. As in the user presses a key and the MIDI turns it into the pitch and the length of the note and etc
   • Remote control

5. Direct data entry

   • OCR
     • The text produced is not always reliable, particularly if the copy is smudged or unclear.
     • Can make the input of data from hard documents quick.
   • OMR
     • Extremely fast and more reliable than other methods
     • The sheets may not be read properly if they are not properly lined up or there are dirty marks on the paper that may be misinterpreted by the computer
   • Bar code readers
     • A set of parallel lines varying in thickness that are interpreted by a laser that reads the reflection of how thick the lines are. They can stand for numbers. It is much faster than using a keyboard and more accurate than a human. The info on a barcode on a typical supermarket barcode: Country of origin number, manufacturer number, item number, check digit.
   • RFID Readers
     • Radio-frequency Identification consists of a small chip and antenna. The RFID only works when you are within a few metres. If all items in a supermarket had a RFID you could put them on a platform and they would all be totalled up.
   • Magnetic stripe cards
     • On bank cards
     • If the card is lost there is no identifying what it belongs to so it cannot be used to steal.
     • The info can be easily read or altered by a device bought on the web
   • Chip and pin readers
     • The user types in the PIN and is checked against the code in the card and if the two match the action goes through
     • Information is secure because the chip is difficult to read
     • People tend to be careless when they use their pin
   • Smartcards
     • Convenience and speed
     • Allow users to make payments without the use of a Pin. It is preloaded with money. Generally only used for small payments