2.6

2.6

1. Denary, Binary and Hexadecimal

   • Binary numbers are stored as bytes
   • A hex digit is 4 bits in size
     • Hex uses the denary values 1-9, then 10-15 is A,B,C,D,E,F
   • Binary shifts
     • A binary left shift doubles the number
     • A binary right shift halves the number
   • To convert from binary to denary, values must be input from left to right, biggest to smallest
     • To convert from binary to hexadecimal, the the first 4 values must be input from left to right, then the next 4 values the same
   • Data must be stored in binary, as it is the only language a computer can understand...
     • ...with the 1's and 0's reflecting the on and off states of the transistors in the circuits

2. Character sets

   • ASCII is a 7 bit character set (stores 2^7 characters)
     • Stores standard English alphabet and symbols
   • Extended ASCII is an 8 bit character set (stores 2^8 characters)
     • Stores accents/letters from other languages
   • Unicode is a 16 bit character set (stores 2^16 characters)
     • Unicode was made to store characters and symbols from other languages

3. Images

   • Images are represented by a sequence of binary values
   • The colour depth is the number of colours that can be stored in the image
     • E.g. 2 bit colour depth can store 4 colours (2^2)
   • A higher resolution = better quality image
   • Metadata includes colour depth and resolution

4. Sound

   • Sound is stored as a series of binary values
     • Sampling is when the amplitude of the analogue audio wave is recorded at regular intervals
       • The sampling frequency is how regularly the amplitude of the wave is recorded
         • The higher the frequency, the higher quality of the audio file

5. Compression

   • Types of compression
     • Lossy
       • Using lossy, the quality of the file will be reduced
     • Lossless
       • Using lossless, no quality (too minimal to notice) will be lost
   • Compression is used to reduce the size of files
     • Advantages of compression
       • Faster loading times
       • Smaller file sizes
     • Disadvantages of compression
       • Reduced quality