Operating Systems (Edexcel IGCSE ICT)

Role & function of an operating system

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