computing

• Abstraction


  Removing unnecessary details from a problem in order to solve it
• Decomposition


  Breaking down a problem into smaller, simpler steps or stages
• Linear search


  Look at every item from the beginning until you find the one you want
• Binary search


  Dividing halves until data is found
• Bubble sort


  Comparing each pair and swapping if in wrong order
• Sequence


  Writing steps down in the order they need to happen
• Validation


  • Range check
  • Type check-right integer
  • Length check
  • Presence check-data has been entered
  • Format check
• Syntax error

  Wrong format
• Logic error

  Doesn't do what expected
• Types of testing


  • Iterative testing
  • Terminal testing
• High level languages


  Easy to learn and look a bit like English or maths
• Low level languages


  Assembly languages and machine code
• Assembler


  Converts assembly language into machine code
• Compiler


  Translates a program from high level programming language into machine code
• Interpreter


  Translates high level language into machine code, translates each line and executes it and no object code is produced
• Low-level language


  A programming language that directly translates to machine code understood by the processor
• Generations of programming languages

  • Low-level
  • High-level
• First generation low-level language

  • Machine code - instructions are directly executable by the processor, written in binary code
• Second generation low-level language

  • Assembly code - code written using mnemonics (abbreviated text commands), needs to be translated into machine code
• Advantages of low-level languages

  Complete control over system components, occupy less memory and execute faster, direct manipulation of hardware
• Disadvantages of low-level languages


  Difficult to write and understand, machine dependent, more prone to errors, knowledge of computer architecture is key
• High-level programming language


  Uses English-like statements to allow users to program with easy to use code
• Advantages of high-level languages

  Easier to read and write, easier to debug, portable so can be used on any computer, one line of code can perform multiple commands
• Disadvantages of high-level languages

  User is not able to directly manipulate the hardware, needs to be translated to machine code before running, the program may be less efficient
• Examples of high-level languages


  • Python, Java, Basic, C++
• Translator


  Converts high-level language into machine code that the computer can execute
• Compiler


  Translates the entire program at once before it is run
• Interpreter


  Translates and executes the program line by line
• Computers represent all data in binary, including images that are seen on a screen, TV or other output device
• Bitmap


  A bitmap image is made up of squares called pixels. Each pixel is stored as a binary code. A typical example is a photograph.
• Vector


  A vector image is created from mathematical equations and points. Only the mathematics used to create the image are stored. Typical examples are logos and clipart. Vector images are infinitely scalable.
• Resolution


  The total amount of pixels that make up a bitmap image, calculated by multiplying the height and width. Higher resolution means more detail (higher quality).
• Colour depth


  The number of bits stored per pixel in a bitmap image. Higher colour depth means more colours and more detail (higher quality).
• As resolution and/or colour depth increases

  The file size becomes larger
• Metadata


  Additional information stored with an image, such as author, date/time, location, resolution, colour depth.
• Metadata


  • Author
  • Date/Time
  • Location