The role of the operating system

What an OS is

An operating system is system software that manages the computer's hardware and resources and provides services to applications and users. Without it, every program would have to control the hardware itself. Examples of tasks it hides: reading a file from a disk, sharing the CPU between programs, sending output to a printer.

The five roles

• User interface: lets the user interact with the computer, for example a graphical user interface (GUI) with windows, icons, menus and a pointer, or a command-line interface (CLI) where commands are typed.
• User management: user accounts, logging in (authentication) and access rights or permissions, so users can only reach their own files and the resources they are allowed.
• Peripheral management: communicates with input, output and storage devices using device drivers; manages buffers and queues, for example a print queue.
• Process management: creates, schedules and ends processes, sharing CPU time between them (multitasking).
• Memory management: allocates memory to processes, keeps track of which parts are in use and protects each process's memory from others.

GUI or CLI?

A GUI is easy to learn and suits most users but uses more memory and processing. A CLI needs commands to be learned but is fast for experts, uses few resources and makes tasks easy to automate with scripts.

Worked example

A user plugs in a new printer. Describe the OS roles involved in printing a document.

1. Peripheral management: the OS uses the printer's device driver to translate output into commands the printer understands.
2. It places the job in a print queue (spooling) so the user can keep working.
3. User management: the OS can check the user has permission to use that printer.

Answer: Mainly peripheral management (driver, queue), with user management checking permissions.

Check yourself

1. Which OS role uses device drivers?
   • User management
   • Peripheral management
   • Memory management
   • Process management
   Show answer

   Peripheral management. Drivers let the OS talk to specific hardware devices.

2. Which OS role controls which files each user can open?
   • Peripheral management
   • Memory management
   • Process management
   • User management
   Show answer

   User management. Accounts and access rights are part of user management.

3. Which OS role stops one program from overwriting another program's data in RAM?
   • User interface
   • Memory management
   • Peripheral management
   • User management
   Show answer

   Memory management. The memory manager allocates and protects memory areas.

4. Which is a benefit of a command-line interface over a GUI?
   • It is easier for beginners to learn
   • It does not need any commands to be remembered
   • It uses fewer system resources and tasks can be scripted
   • It shows icons for every file
   Show answer

   It uses fewer system resources and tasks can be scripted. CLIs are lightweight and good for automation, but harder to learn.

5. Explain why a computer needs an operating system.
   Show answer

   It manages the hardware and resources such as the CPU, memory and devices, and provides an interface and services so that users and applications do not have to control the hardware directly.. Mention managing hardware/resources and providing a platform for programs and users.

6. Which OS role decides which program uses the CPU next?
   • Peripheral management
   • User management
   • Process management
   • User interface
   Show answer

   Process management. Scheduling is part of process management.

Practise with instant feedback Print this lesson

Sources

• Pearson Edexcel International Advanced Subsidiary/Advanced Level in Computer Science specification (2026)

Last updated 8 November 2026. Spotted a mistake? Tell us.