1.4 - Input Devices Flashcards
Describe touch screens
- senses when an area of screen has been touched by wires or infra red light beams
- used in public areas as they’re easy to use and combine input and output
Describe a graphics tablet
- mainly used for drawing
- stylus is used to draw on a flat plate
Describe speech recognition
- involves user speaking into a microphone
- sounds of words are compared with collection of sounds and are converted into computer readable text using special software
Why is speech recognition not very reliable?
- different accents and voices can be interpreted wrong
- background noise can interfere
- words that sound the same but are spelt differently can not be distinguished so the context has to be looked at
Describe magnetic strip cards
-they are swiped through a card reader and are easy to read but can easily be scratched and they don’t hold much data
Describe a smart card e.g chip and pin
- has a computer chip which can have data written on to it and it can hold a lot
- authorised by a pin number so it is more secure
- chip allows data to be encrypted
Describe RFID (radio frequency identification)
- uses radio waves to transmit a unique serial number as a form of ID for objects
- tag can be attached which can be used to track the position of the item
- sometimes called smart labels
- used in transport to trace goods that may be of good value
Describe a scanner
- used to turn paper based pictures into digital images
- a beam of light passes across the page and senses the colour of various aread
Describe an Optical Mark Recognition
- used for lottery tickets and multiple choice exams
- uses a light beam to sense the position of marks on the paper
What are the advantages and disadvantages of an OMR?
- expensive to set up
- inflexible as only allows users to select from a list of choices
- results are quick and accurate when there is a large volume of data
Describe Optical Character Recognition (OCR)
- a paper document is scanned and each part of the image is compared to a dictionary of known shapes to convert it to text
- used for input forms which have been filled out by client
Describe barcode readers
- used in EPOS systems (paying in store)
- they have built in error checking
- a barcode can be scanned which enters the product number into the computer system
Describe MICR (magnetic ink character recognition)
- used by banks to process cheques
- cheque number is printed using magnetic ink
- magnetic reader then translates these into numbers that can be stored in the computer systen
Describe sound input
Sound has to be encoded as a digital signal to be entered into the computer
Describe video input
-video cameras can record the still pictures and the data can be loaded onto a computer to be edited
Describe webcams
-small video cameras used for video conferencing
Describe digital cameras
Records images of a scene being photographed
How can standard input devices be adapted to make them useable for a wide range of people?
- pointer speed can make positioning easier
- buttons on mouse can be set for left or right hand
- single keystrokes can be adjusted to remove combined ones e.g ctrl/alr delete
Describe games controllers
Often demand fast response times
What to think about when choosing an input device?
- type of data
- volume of data
- user preferences
- cost consideration
- where the device will be used
Types of computer inputs
- number
- text
- still images
- moving images
- sound
Accessible input devices
- footmouse
- puff suck switch
- eye typer(mouse clicks with blink)
- braille keyboard
- speakers
- zoom tool
- sticky keyboard
Difference between input device and media?
Device-hardware
Media-medium where the data is stored
Describe a concept keyboard
- used in restaurants
- user can press name of item rather than remember the price
Explain different mouses
- most common pointing device
- mechanical and optical mouse
- trackball is used on laptops, easier in confined spaces
- trackpads are moving fingers over sensitive plates
- trackpoint is small button which works like a joystick
