Characters

Characters

1. Binary can be used to represent characters.

   • due to computers not being able to process regular numbers.

2. alphanumeric characters are used to make words and strings

   • include: uppercase and lowercase letters, the digits 0-9, and symbols such as ? and £

3. character sets

   • character sets are collections of characters that a computer recognises from their binary representation
   • also contain special characters which do certain commands such as enter and delete
   • the number of bits that you'll need is based on the character set that you're using

4. pressing a button on your keyboard sends a binary signal to your computer.

   • this signal tells the computer which key you pressed
     • the computer then translates the binary into the character that you have pressed.

5. file size (in bits) = number of bits per character x number of characeters

   • e.g. a text file that uses 8bits per character and contains 200 characters will have a file size of 1600bits

6. ASCII

   • most common character set
   • each character is given a 7bit binary code
     • it can represent a total of 128 different characters
   • and extra 0 is added at the start of the binary code so that it fits into 1byte

7. Unicode

   • tries to cover every letter and symbol that is possible
   • uses multiple bytes for each character
   • covers all major languages
     • including Greek, Russian, and Chinese even though they have a completely different alphabet.
   • first 128 codes are the same as they are in ASCII