Data Representation

Data Representation

1. Sound

   • Stored as binary numbers. Certain number of samples taken per second and each holds a binary number representing the pressure level of the sound.
     • Samples recorded at around 48kHz (48000 samples/second).
     • Bitrate determines no. pressure levels which can be represented in each sample.

2. Numbers

   • Binary
     • Base 2.
     • Goes 0, 1.
     • Used in computers to store anything as computers use transistors which only accept on (1) or off (0).
   • Hexadecimal
     • Base 16.
     • Goes 1, 2, 3, 4, 5, 6, 7, 8, 9, A B, C, D, E, F.
     • Used to represent binary as its simpler but easily converted from/to binary.

3. Images

   • Stored by each pixel being represented by a binary number which determines a colour.
   • Metadata such as height, width and colour depth will be stored with the file so that it can be formatted correctly.
   • Higher colour depth means more colours available per pixel but takes up more space as larger binary number needed.

4. Character Sets

   • Character sets are tables which map characters with a unique binary number.
   • ASCII = American Standard Code for Information Interchange
     • Holds 256 characters. 1 byte/character.
   • Unicode
     • Is larger than ASCII as it contains more characters but is able to support different languages (e.g. Russian Alphabet).
       • Takes up more storage per character than ASCII because a larger binary number is required.

5. Memory Types: Refer to flashcards.

6. Data Types

   • Integer: whole number.
   • Character: single character.
   • Real/Float: fractional and decimal numbers.
   • String: sequence of characters.
   • Boolean: true (1) or false (0).

7. Truth tables: simple.