An operating system (OS) is the computer program (software) responsible for the operation and smooth running of a computer.
Most general purpose computers (including smartphones and tablets) will have an operating system to manage the running of other programs and control the system’s inputs and outputs.
Operating systems usually provide a graphical user interface (GUI) to help users to interact with the computer, however successful operating systems can also function from a command line interface (CLI).
Our User Interface Design page explains all about a variety of interfaces.
Examples of operating systems include:
- Microsoft Windows
- Mac OS
Functions of an operating system
Operating systems have many functions:
- Provides an interface for computer interaction
- Control of inputs and outputs
- Interrupt and error handling
- Management of hardware and peripherals
- Management and loading of software
- File management (copy, save, sort, delete)
- Processor management for multitasking
- Memory management
- Security (access rights, user accounts, firewalls etc)
- Network communication
A user interface provides a way for the user to interact with the computer.
Without it, most computers would be too difficult for the average person to use.
Management of hardware and peripherals
The operating system is responsible for controlling all the devices connected to the computer. It tells them how to interact and operate correctly.
Device drivers are used to manage these connections.
Running of software
The operating system runs programs, allowing them to function as designed.
Programs are designed to run on a particular operating system. This enables them to benefit from the existing connections and functions available.
The operating system manages the CPU.
When software is opened, the OS finds it and loads it into memory (RAM).
The CPU can then be instructed to execute the program.
The operating system will manage the sharing of processor time.
Interrupt and error handling
Several programs can be stored in RAM at the same time, but the processor can only process one at a time.
Through the use of regular interruption signals, the OS can prioritise and juggle the requests made to the processor.
This gives the illusion that the CPU is actually dealing with more than one program or task at once (multitasking).
Errors are spotted and usually dealt with without needing to alert the user.
Our interrupt page explains more about interrupts
The operating system is responsible for transferring programs to and from memory.
It keeps track of memory usage, and decides how much should be given to each program.
The OS also decides what happens if there is not enough memory.
A file system is created to organise files and directories.
This gives programs a consistent way to store and retrieve data.
The OS is also responsible for the naming, sorting, deleting, moving and copying of files (at the request of the user).
Look-up tables are used to relate file names to storage locations.
The operating system is responsible for the creation and application of user accounts and passwords.
An OS also comes with many utility programs, including firewalls.