Data Representation

Data Representation

1. Date Storage Units

   • Bit
     • Nybble
       • Byte
         • Kilobyte
           • Megabyte
             • Gigabyte
               • Terabyte
                 • Petabyte
                   • Exabyte
                     • Zettabyte
                       • Yottabyte

2. Images on a computer system are made up of thousands of small coloured dots, known as pixels. Bitmap images are stored as an array of pixels. A black and white bitmap image will store a 1 for a black pixel and 0 for a white pixel.

   • A color bitmap image is stored by replacing the 1s and 0s above with a longer number that represents how much red, green and blue is required in the color of each pixel

3. Binary/Denary/Hexadecimal

   • Binary
     • In order for data to be processed by a computer system, it must be converted into binary format. This is because computer systems can only store and process Binary digITs, also known as BITs. A BIT is either a 1 or 0.
     • The binary number for the denary number 198 is 11000110 (128 + 64 + 4 + 2).
   • Hex
     • In the hexadecimal counting system, the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 are used to represent 1–9 and then the characters A, B, C, D, E and F are used to represent 10 –15.
     • The hexadecimal number for the denary number 198 is therefore C6
   • Denary
     • In the denary counting system, the digits 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 are used to represent numbers
     • The denary number for the hexadecimal number C6 is therefore 198

4. Sound

   • Sound is converted into a digital signal by a process called sampling. Sampling is where hardware, such as a microphone, measures the level of sound many times per second and records this as binary digits.