Hardware Devices

Hardware Devices

1. Mouse

   • First prototype made in 1964 by Douglas Engelbart
     • It was orginally a wooden shell  with 2 metal wheels
     • Works by detecting movement in the 2 axes and uses this and clicks to control the GUI

2. Keyboard

   • Used to enter text into a computer system
     • Electronic components of the keyboard continuously scan the rows of keys to detect the pressing of a key or key combination
       • The scan code is sent to the computer and software interprets the code and turn it into ASCII or Unicode

3. Bar Code Reader

   • A device used for reading bar codes on cans, packaging and books
     • A bar code is a sequence of black and white bars which encoodes information such as a product identifier
     • The reader consists of a light source, lens, photoelectric detectors and decoder circuitry to analyse the data of the bar code
       • Since more light is reflected from a white band than a black, the pattern is recorded and converted to electrical form by the photoelectric detectors and the data in the bar code is interpreted.

4. Scanners

   • Captures an electrical equivalent of a picture, printed text or handwriting and produces a digital representation which can be stored in the computer
   • Flatbed Scanner
     • Usually a back-lit glass pane with an array of light-detecting sensors spanning the width of the glass
       • These scanners are moved along the length of the glass pane and picks up reflected light. Colour scanners have 3 rows of arrays with red, green and blue sensors which measure the intensity of the colours
         • A digitised image of the scanned area is created and it can then be processed and stored by the computer attached to the scanner
   • Fingerprint Scanner