1.2) Input Devices- keyboards and pointing devices.
Students should be able to: evaluate a range of input and output devices: keyboards, pointing devices, smart cards, bar codes, OMR, MICR, ATM, touch screen, printers, plotters, monitors, scanner, sensors, interactive white board, data projectors, OCR, speech input, speech output and actuators;
Keyboards:
Have keys which when pressed send digital code to the computer which gives computers commands.
4 groups of keys on QWERTY keyboard are:
Numeric
Function
Cursor
Alphabetic
Concept keyboard
Overlays on keyboard with text or pictures.
Keys sensitive aresa of a plastic surface.
Easy to operate.
Use in a restaurant.
Advantages:
Fast input of data
can be wiped clean.
Limited choices so less chance of making mistakes.
Mouse
Has a rotating ball.
Movement detected by sensors.
hand used to move mouse on flat surface making cursor correspond.
When a button is pressed it sends signal to the computer.
Trackerball
Like an upside down mouse, stays still, the user moves the ball and is used on laptop computers.
Touch Sensitive Pad (Tracker Pad)
The screen is an input and output device.
The screen is covered by a membrane/ a line of infrared sensors/ along the edges of the screen which is sensitive to pressure.
The pressure of the users finger is detected.
The finger cuts the beam and an X and Y position is calculated.
Joystick
As the stick is moved forwards/ backwards/ left/ right the movement is detected by sensors/ switches which detect the X and Y coordinates of the stick.
A sensor detects the depression of the button.
the signals from the sensors are input to the computer.
AD (Analogue-->Digital) conversion may be used.