Operating Systems (Edexcel IGCSE ICT)
Revision Note
Written by: Robert Hampton
Reviewed by: James Woodhouse
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
Single user | Network |
|---|---|
Allow for a single general user | Provide access to network storage and shared resources |
No option to customise user interface for different users | Server is sent requests when users log in with usernames and passwords |
Typically used in a household appliances | User accounts are kept separate to ensure users cannot access each other's files |
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]
Marks can be awarded across mark points
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