Operating Systems (Edexcel IGCSE Ict)

Role & function of an operating system

Spec point — 1.3.3

What is an operating system?

• An operating system (OS) is software that provides an interface between the user and the hardware in a computer system

• An operating system hides the complexities of the hardware from the user, for example:

  • A user does not need to know 'where' on secondary storage data is kept, just that it is saved for when they want it again

• There are two main types of operating systems:

  • Single User Operating System
  • Network Operating Systems (NOS)

• An operating system has many functions, this includes:

  • Memory management
  • Resource management
  • Security
  • Print spooling

Single user and network operating systems

Resource management

• Memory

  • Memory management is a process carried out by the operating system allocating main memory (RAM) between different programs that are open at the same time
  • The OS is responsible for copying programs and data from secondary to primary storage as it is needed
  • Programs and data require different amounts of RAM to operate efficiently and the OS manages this process
  • RAM is allocated based on priority and fairness, for example, system applications (essential) may have a higher priority than user applications
  • The OS dynamically manages the memory, adjusting allocation as needed to maintain optimal system performance
  • Memory management makes multitasking possible

• Processor

  • Processor management is a process carried out by the operating system dividing time (time slicing) in to small chunks and allocating them to different programs
  • The CPU can only execute one instruction at a time, it can can execute billions of them in one second.
  • The OS decides what programs get access to the CPU to give a user the perception of being able to use multiple programs at the same time (multitasking)

• Inputs & outputs

  • Input/output (I/O) management is a process carried out by the operating system managing the way input and output devices interact with software
  • The OS allocates system resources to inputs/outputs to ensure efficient operation
  • I/O management makes plug-and-play (PnP) functionality possible, automatically detecting and configuring new inputs/outputs without the need for manually installing device drivers or power cycling the system

• Files

  • File management is a process carried out by the operating system creating, organising, manipulating and accessing files and folders on a computer system

  • The OS manages where data is stored in both primary and secondary storage

  • File management gives the user the ability to:

    • Create files/folders
    • Name files/folders
    • Rename files/folders
    • Copy files/folders
    • Move files/folders
    • Delete files/folders

  • The OS allows users to control who can access, modify and delete files/folders (permissions)

  • The OS provides a search facility to find specific files based on various criteria

Security

• Security management is a process carried out by the operating system enabling different users to log onto a computer
• A system administrator is able to allocate different access rights for different users on a network
• The OS is able to maintain settings for individual users, such as desktop backgrounds, icons and colour schemes
• The OS audits(keeps a log of) files created by users, accesses, edits and deletes
• Operating systems can provide software firewalls

Print spooling

• Print spooling is a process carried out by the operating system when printing is required
• The spooler creates a temporary holding area (queue) for the print job
• Queuing pages increases efficiency

Worked Example Explain one reason an administrator would use a network operating system to manage users.

[2]

Answer

A linked explanation such as:

• Multiple people can use the same computer [1] because users can be added/deleted [1]

• Only specific users can securely access their storage space [1] because user permissions can be edited [1]

• Only certain users can install programs / access certain files [1] because user permissions can be enforced [1]

• The limited storage on the machine can be shared [1] because the amount of resources/storage each user can access can be controlled [1]

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