1.5

• What is an OS?

  An operating system. It manages hardware and runs software.
• What is system software?

  It is software needed to run or maintain computer systems
• What are the main 6 purposes of the OS?

  1. Communicate with hardware

  2. Provide a user interface

  3. Provide a platform for applications

  4. Control the CPU and memory allocation

  5. Manage security

  6. Deal with file and disk management
• What does an OS need to communicate with the hardware?

  Device Driver software. Each piece of hardware might require a different device driver software.
• How do device drivers work?

  Functions as a translator for the signals between the hardware and the OS. The OS will install the required device drivers when it detects a new device
• What is a user interface?

  a system that allows a computer and a user to interact and perform useful functions
• What are the 2 main types of user interface?

  GUI (Graphical User Interface)

  Command Line Interface
• What is a GUI?

  It is a system that allows users to interact with the computer system using graphics such as icons and menus.
• What is a Command Line Interface?

  It is a system that allows users to interact with the computer system in the form of lines of text
• What are the pros of GUIs?

  They are easy to use

  They are interactive and intuitive
• What are the cons of GUIs?


  They can be very resource heavy
• What are the pros of Command Line Interfaces?

  Less resource heavy

  Can be automated

  powerful and efficient
• What are the cons of Command Line Interfaces?

  Difficult to use
• How does the OS provide a platform to run applications?

  By configuring hardware so they can use it, and giving it access to the CPU and memory
• How does the OS multi-task?

  By efficiently managing memory resources and CPU processing time
• What is the multi-tasking process like?

  1) When an application is opened, the necessary parts are moved to memory. The OS decides when to remove programs from memory if they have not been used recently.

  
  

  2) To run multiple apps, the OS needs to ensure they don't overwrite or interfere with each other. A memory manager allocates memory resources to each app.

  
  

  3) Then CPU time is distributed between each app and is carried out in the most efficient order.
• How is multi-tasking done?

  In reality, the CPU just switches from task to task really quckly.
• How does the OS manage file and disk space?

  It deals with the movement, editing and deletion of data, and organises space on the HDD and allocates space into sectors and tracks free space available.
• What are the two types of OS regarding user accounts?

  Single User

  Multi User
• What do OS do for security?

  Regulate what data users can access, so that they can't access others personal data
• What is defragmentation software?

  On hard disk drives, data can become disorganised after long periods of modifying, deleting and creating it. This increases read/write times. The software reorganises the data, which decreases read/write times.
• What are the two types of back ups?

  Full

  Incremental
• What is a full backup?

  All files are backed up. Takes up a lot of storage, slow to back up. Quick to restore
• What is an incremental backup?

  All modified or created files since the last back up is only copied. Takes up less storage, is quick to back up, is slow to restore
• What is a back up?

  It is a copy of all the files and data of a computer system that is stored externally, so it can be recovered if the original is lost.
• What does compression software do?

  Reduces the sizes of files so they take up less files. Compressed files must be extracted before they can be used.
• What does encryption software do?

  Scrambles data so that unauthorised users can't access it