Operating System

Operating System

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An operating system (OS) is system software that manages computer hardware and software resources and provides common services for computer programs. The operating system is a vital component of the system software in a computer system. Application programs usually require an operating system to function.

Overview

Operating systems perform basic tasks such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers. For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop—it makes sure that different programs and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.

Types of Operating Systems

Operating systems usually come pre-loaded on any computer you buy. Most people use the operating system that comes with their computer, but it's possible to upgrade or even change operating systems. The three most common operating systems for personal computers are Microsoft Windows, macOS, and Linux.

Real-time Operating System (RTOS)

A real-time operating system is used to control machinery, scientific instruments, and industrial systems. An RTOS typically has very little user-interface capability, and no end-user utilities, since the system will be a "sealed box" when delivered for use. A very important part of an RTOS is managing the resources of the computer so that a particular operation executes in precisely the same amount of time, every time it occurs.

Multi-user and Single-user Operating Systems

A multi-user operating system allows many different users to take advantage of the computer's resources simultaneously. The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn't affect the entire community of users. Unix, VMS, and mainframe operating systems, such as MVS, are examples of multi-user operating systems.

Multi-tasking and Single-tasking Operating Systems

When a single program is allowed to run at a time, the system is grouped under a single-tasking system. However, when the system allows the execution of multiple tasks at one time, it is classified as a multi-tasking operating system. Multi-tasking can be of two types: pre-emptive or co-operative. In pre-emptive multitasking, the operating system parcels out CPU time slices to each program. In cooperative multitasking, each program can control the CPU for as long as it needs it.

History

The first operating system used for real work was GM-NAA I/O, produced in 1956 by General Motors' research division for its IBM 704. Most other early operating systems for IBM mainframes were also produced by customers.

Examples of Operating Systems

• Microsoft Windows
• macOS
• Linux
• Unix
• Android
• iOS

See also

• Computer architecture
• Kernel
• Virtual memory
• File system