Nepedia
Back to Discover
Advanced Reader
💻

Operating system

technology Maturity 11-13 Next article →

An operating system, or OS, is the essential system software that manages a computer's hardware and software resources. It acts as a vital intermediary between user applications and the physical computer hardware. Without an OS, a programmer would have to write code for every specific piece of hardware used by a machine. Instead, the OS provides common services and an interface that abstracts these complex hardware details. This allows applications to run on different hardware without needing to be rewritten.

Kernel Layout
Kernel Layout

At the heart of every operating system is the kernel. The kernel is the software that is always running. Other programs on a computer are divided into two categories: system programs and applications. System programs are associated with the OS but might not be part of the kernel itself. Applications are all other software that users interact with directly. The OS manages these by allocating resources like the central processing unit (CPU) and memory.

Layers of a Linux system
Layers of a Linux system

Resource allocation is a primary mechanism for how an OS functions. On modern personal computers, users often run several applications at the same time. To prevent one program from monopolizing all the hardware, the OS gives each application a specific share of time on the CPU or space in the memory. It also uses virtualization to mask limited resources. For example, virtual memory can give a program the illusion of having nearly unlimited memory. This is achieved by using memory that exceeds the computer's actual physical capacity.

Virtual memory
Virtual memory

Operating systems come in many different types designed for specific tasks. Multicomputer operating systems manage machines where multiple CPUs share memory. In contrast, a distributed system consists of a group of distinct, networked computers that may be located anywhere in the world. Some systems are "embedded," meaning they are built into household appliances or Internet of Things objects. These embedded systems often do not load user-installed software, allowing for simpler designs. Some are even small enough to run on smart cards using less than 10 kilobytes of space.

Dolphin FileManager
Dolphin FileManager

Another specialized type is the real-time operating system. These systems guarantee that they will process data or events at a specific moment in time. "Hard" real-time systems require exact timing and are used in military or aviation settings. "Soft" real-time systems can tolerate occasional missed events, which is common in smartphone multimedia. There are also hypervisors, which are operating systems that run a virtual machine. A virtual machine is an application that emulates hardware, allowing researchers to test different operating systems easily.

The history of the operating system shows a massive evolution in computing. In the 1940s and 1950s, computers were programmed directly using plugboards or punch cards. There were no operating systems during this era. In the 1960s, IBM introduced OS/360, which was the first popular system to support multiprogramming. This allowed a computer to work on another job if one was waiting for input/output operations.

IBM system 360-50 console - MfK Bern
IBM system 360-50 console - MfK Bern

Later, the UNIX operating system emerged from the MULTICS project. UNIX became the foundation for many other systems, including the educational MINIX, which inspired the creation of Linux.

As personal computers became common around 1980, the interface of the OS changed significantly. Early systems used a command-line interface, where users typed text commands.

MS-Dos screenshot
MS-Dos screenshot

This changed with the Apple Macintosh, which was the first popular computer to use a graphical user interface (GUI). A GUI uses icons and pictures to make the computer more user-friendly. This success led Microsoft to create Windows, which eventually became a stand-alone operating system. Today, these interfaces are standard on almost all consumer devices.

Modern market shares show how diverse the OS landscape has become. Android is currently the most popular operating system with a 38% market share. Microsoft Windows follows with 33%, and iOS and iPadOS hold 15%. macOS has a 4% share, while Linux holds 1%. While Windows is common on desktops, Linux dominates the server and supercomputing sectors. This variety ensures that whether a device is a tiny smart card or a massive supercomputer, there is a specialized system to manage it.

676 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (8)
File:IBM system 360-50 console - MfK Bern.jpg
IBM system 360-50 console - MfK Bern.jpg
File:MS-Dos screenshot.png
MS-Dos screenshot.png
File:System 1 File Edit.png
System 1 File Edit.png
File:Kernel Layout.svg
Kernel Layout.svg
File:Virtual memory.svg
Virtual memory.svg
File:Dolphin FileManager.png
Dolphin FileManager.png
File:Layers of a Linux system.png
Layers of a Linux system.png
File:Diagram of a security descriptor for a file on Windows.png
Diagram of a security descriptor for a...
More to explore

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.