Software

• Software - Series of instructions written in a programming language that performs a functions.
• Operating system - Program that manages the computer, allows the user to communicate with the power and allows software to be run.
• Application software - Software that allows the user to perform a useful task.
• Example of Application software:

  Word processor

  Spreadsheet

  Database

  Web browser
• Bootstrap --> Firmware --> Operating system --> Application software
• Firmware - Instructions that are stored in ROM and are loaded when computer starts.
• Bootstrap - First commands loaded when a computer starts, checks hardware and loads firmware,
• Interface - <Method by which a user communicates with a computer.
• Types of interface:

  • Graphical User Interface
  • Command line interface
  • Natural language interface
• Graphical User Interface - Type of operating system that includes windows, icons, menus and pointers.
• Command line interface - Type of operating system where the user types commands
• Natural language interface - Type of operating system that allows the user to type or speak commands.
• Operating system manages:

  • Files
  • Peripherals and drivers
  • Memory
  • Multitasking
  • Interrupts
  • User accounts
• Peripherals - Hardware device used to input, store or output data from computer. Not directly part of computer itself.
• Interrupts handler - Program that organises interrupts into an order based upon priorities.
• Interrupt service routine - Program that retrieves an interrupt and performs the required actions.
• High-level language - Type of programming language that uses English-like commands.
• Low-level language - Language closer to machine's language (assembly language, binary code)
• Assembly language - Code written in memonics that allows direct manipulation of hardware. Must be converted to binary code to run.
• Translator - Type of software that converts code from one language to another, usually high to low level language.
• Interpreter - Translator that converts high level language into low level language. Checks one line of code then executes before checking the next.
• Compiler - Translator that converts high level language to low level language. Checks all code before running program.
• Executable file - File produced by compiler that can run independent of translator software and does not include source code.