Operating Systems

• what are the 7 purposes of an OS?

  • user interface

  • memory management

  • multitasking management

  • peripheral management

  • management of drivers

  • user management

  • file management
• what is an OS?

  something which provides an interface between the user and the hardware
• what is command line interface?

  a text based OS
• what is a graphical user interface?

  a visual interface containing graphics etc
• pros of command line interface

  • better for expert users

  • uses less system resources
• cons of command line interface

  • requires complex commands which are hard to learn
• what type of people use command line interface?

  people who require the maximum performance of the computer
• what are device drivers?

  software loaded into memory by the OS, and used to control the operating of a hardware component
• pros of using graphical user interface (GUI)

  • easy to use

  • appealing to look at
• con of GUI

  requires lots of system resources, meaning less power can be used for actual tasks
• how does an OS manage multitasking?

  it allocates a small time slice to separate processes, to give to illusion that many processes are happening at the same time
• how does the OS manage memory?

  it allocates the memory between the different programs
• how does an OS manage drivers and peripherals?

  it provides an interface between the hardware and the applications, allowing them to work
• how does an OS manage users?

  allows security to be managed with different user access levels and settings
• how does an OS manage files?

  • it must identify where files are stored for long-term storage, as the user does not need to know where

  • includes creating, modifying, deleting files etc
• what is utility software?

  software that performs housekeeping actions to identify and fix problems to keep the device running smoothly
• 3 examples of utility software

  encryption, defragmentation, data compression
• what is defragmentation?

  • when files are deleted from a HDD, it leaves gaps, which are filled up by new files (that can be split across multiple gaps)

  • defragmentation groups these fragmented files together, increasing performance when accessing these files as the head in the HDD moves less
• what is data compression?


  reducing file size by performing an algorithm on the original data
• what is lossless compression?

  original file can be recreated as no data is lost
• what is lossy compression?

  original file cannot be recreated as some data is lost
• what are the advantages of compressing data before it is shared?

  • reduces file size so it takes up less space in storage
  • quicker upload and download speeds
  • reduces the chance of exceeding the data limit in email
• how does compression work?

  an algorithm is executed that would affect the data and its file size