A computer is a machine which takes data and instruction from the user through the input devices, processes them in the CPU, and produces the useful information through the output device.
Input devices
1. Keyboard :
Popular device.
has numbers, letters and special characters
has function keys
2. Mouse
Input devices
1. Keyboard :
2. Mouse
- Mechanical Mouse
- has a metal or rubber ball at the bottom, which rotates when the mouse is moved.
- as the ball rotates, it moves the 3 rollers at the bottom.
- it generates electrical signals which indicates the mouse direction
- popular, less expensive
- Optical Mouse
- uses light beam instead of balls.
- has a wheel with tiny holes
- has light source and light sensor
- it lasts longer since there is no moving parts like balls or rollers
- pointing device
- has a stick with a plastic base
- used to play computer games
- also used in mobile phone, flight simulator
- pointing device
- draw images on the screen
- senses light from the screen, and generates a pulse
- pointing device
- has a ball which can be rotated in all directions
- ball controls the movement of the pointer
- used in laptops
- generates soft copy
- can be saved or edited
- small in size
- moves over the document number of times to get the result
- low quality image
- scans in one go
- light sensor move over the document
- high quality image
- document is moved over the scan head
- only paper can be scanned
- expensive
- high resolution output
- drum rolls over the entire document
- stores images in digital form
- has electrical sensor and memory card
- better quality image
- can be downloaded to computer
- images can be stored
- images can be modified
- photoshop, CorelDraw,Photo Editor etc., are the image editing software
- draws images, graphics
- has a flat surface and a stylus
- captures handwritten signatures ( like the one used in IPL matches to get the captains' signatures)
