IGCSE Computing - Data Representation

IGCSE Computing - Data Representation

1. Binary

   • Written as 1's and 0's only
   • Directly controlls computers-all commands end up as binary
     • All data ends up as binary

2. Denary

   • Standard number system
   • Written using numbers from 0 to 9

3. Hexadecimal

   • Written using 0 - 9 and A-F
     • A,B,C,D,E and F represent 10-15
   • Used by computer programmers as a more user-friendly form of binary
     • Each hexadecimal number represents four binary numbers, also known as 'nibbles'

4. Images

   • Two types of image storage- vector and bitmaps
     • Vector
       • Stores shapes of colour as a mathematical formula
       • Useful for storing images with large sections of the same colour
       • As a vector image is magnified, the detail increases due to the mathematical formulae used to create the image
     • Bitmap
       • Stores each pixel as a binary representation of a colour
       • Useful for storing very detailed images consisting of small sections of many different colours
       • As a bitmap image is magnified, it becomes pixelated

5. Sound

   • Sound represented as binary
     • The more bits assigned to the data, the better the quality

6. Files

   • Data stored as binary
     • ASCII codes are used to represent letters, numbers, symbols etc. as binary.
       • Unicode is used to represent special characters not represented in ASCII
         • ASCII uses 7-bit binary, Unicode uses 32-bit, giving it a much wider range of symbols possible to represent

7. Compression

   • Stores the data in as compact a form as possible
   • Different methods