1.2.2 Application Generation

• Software can either be categorised as applications software or systems software
• Applications software

  • Designed to be used by the end-user to perform one specific task
  • Requires systems software in order to run
  • Examples: desktop publishing, word processing, spreadsheets, web browsers
• Systems software

  • Low-level software responsible for running the computer system smoothly
  • Interacts with hardware and provides a platform for applications software to run
  • Ensures high performance for the user
  • Examples: library programs, utility programs, operating system, device drivers
• Utilities

  • Integral to ensuring consistent, high performance of the operating system
  • Each utility program has a specific function linked to the maintenance of the operating system
• Utilities

  1. Compression

  2. Disk defragmentation

  3. Antivirus

  4. Automatic updating

  5. Backup
• Open source

  Code can be used by anyone without a license and is distributed with the source code
• Closed source


  • Code requires the user to hold an appropriate license to use it
  • Users cannot access the source code as the company owns the copyright license
• Advantages of Open source

  • Can be modified and improved by anyone
  • Thorough, regular and well-tested updates
  • Technical support from online community
• Advantages of Closed source


  • Company
• The code requires the user to hold an appropriate license to use it
• Users cannot access the source code as the company owns the copyright license
• Advantages of closed source software

  • Can be modified and improved by anyone
  • Thorough, regular and well-tested updates
  • Technical support from online community
  • Company owning software provides expert support and user manuals
  • Can be modified and sold on
  • High levels of security as developed professionally
• Disadvantages of closed source software

  • Support available online may be insufficient or incorrect
  • No user manuals
  • License restricts how many people can use the software at once
  • Lower security as may not be developed in a controlled environment
  • Users cannot modify and improve software themselves
• Whether a user chooses to use open source or closed source software ultimately depends on the suitability of the software to the task they will be using it for
• Considerations when choosing software

  • Costs - implementation, maintenance, training of staff, license
  • Functionality - features available, ease of use
• A translator converts high-level source code into low-level object code, which is then ready to be executed by a computer
• Types of translators


  • Compiler
  • Interpreter
  • Assembler
• Compiler

  1. Translates high-level code into machine code all at once

  2. If changes need to be made, the whole program must be recompiled
• Compiled code


  Specific to a particular processor type and operating system
• Interpreter


  1. Translates and executes code line-by-line

  2. Code must be translated each time it is executed with an interpreter
• Interpreted code


  • Requires an interpreter in order to run on different devices
  • More portable as it can be executed on a range of platforms
• Assembly code


  Considered to be a low-level language, platform specific
• Assembler

  Translates assembly code into machine code on almost a one-to-one basis
• A small manufacturing business uses networked computers with closed source application software installed.

  (a) A spreadsheet application package is used to calculate employee’s wages. (i) Give one benefit of using a spreadsheet application for this task compared to calculating wages manually

  
  

  • Fewer mistakes / more accurate
  • Faster, apply the same formula
  • Can be shared electronically
• Give two other types of application packages that the small business could use, giving an example of a task that the business could use each application for

  • Word processor - to create documents/letters for clients/staff
  • Graphics manipulation - to produce adverts/images for sales
• Describe a drawback of using closed source software (rather than open source software) for the small business.(3 marks)

  • No access to source code
  • Cost to purchase licenses
  • Cannot fix bugs