Storing Text

  • Each character on keyboard is allocated a numeric equivalent
  • Numeric value is called ASCII code

ASCII

  • ASCII stands for American Standard Code for Information Interchange
  • ASCII code allows computers to understand how to represent text. 
  • In ASCII, each character (letter, number, symbol or control character) is represented by a binary value. 
  • Standard ASCII uses seven bits to represent a character in where the 8th bit is used for error checking).

Extended ASCII – 8 Bits

  • Extended ASCII is a version that supports representation of 256 different characters.  
  • This is because extended ASCII uses eight bits to represent a character as opposed to seven in standard ASCII (where the 8th bit is used for error checking).

This ASCII code number is then converted to binary

 

Extended ASCII 

The number of bits required to store the text

               I Love Computing  Science

There are 24 characters including spaces

24*8 = 192 bits

Standard ASCII

The number of bits required to store the text

               I Love Computing  Science

There are 24 characters including spaces

24*7 = 168 bits

Example

HELLO

ASCII code 72 69 76 76 79 

Binary 

01001000   01000101   01001100   01001100   01001111