Data Representation

Data Representation

1. Conversions

   • Binary
     • 8|4|2|1
       • 1|1|0|0
     • The number below is a binary representation of the denary number above and each 1 represents them. So the first 2 1's represent the 8 and the 4 and they add up to make 12. The two 0's are irrelevant
   • Denary
     • Denary is known as the Base 10 which is just simply the first 10 numbers that add up to make other numbers
       • So 127 will be...
         • 1 'hundred', 2 'tens' and 7 'units'
   • Hex
     • The Hex counting system is known as the Base 16. This is because the numbers go up to 16. But the last 6 numbers are letters.
       • The hexadecimal number 8A therefore represents 8 ‘sixteens’ and 10 ‘units’. This gives the total one hundred and thirty-eight. Remember that A = 10, B = 11, C = 12, D = 13, E = 14, F = 15.

2. Character Sets

   • Unicode
     • Unicode is a standard character set that has combined and replaced many others. It was originally an extension to the ASCII character set and it contains many of the characters used around the world.
   • ASCII
     • 7-bit American Standard Code for Information Interchange (ASCII). Part of the ASCII character set, that includes printable characters only, can be seen in the table overleaf.

3. Data Types

   • Integer
     • Whole Number
   • Real
     • Fractions and Decimals
   • Boolean
     • True or False
   • Character
     • Letters, Digits, Spaces
   • String
     • Sequence of Characters

4. Data Storage

   • Kilobytes = 1024 Bytes
   • Byte = 8 bits
   • Megabyte = 1024 Kilobytes
   • Gigabyte = 1024 Megabytes
   • Terabyte = 1024 Gigabytes
   • Petabyte = 1024 Terabyte
   • Exabyte = 1024 Petabytes