Operating System

 Operating System:

An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.

5 operating system:

 Apple macOS, 

 Microsoft Windows,

 Google's Android OS,

 Linux Operating System,

 and Apple iOS

1.2 WHAT IS AN OPERATING SYSTEM? In a computer system, we find four main components: the hardware, the operating system, the application software and the users. In a computer system the hardware provides the basic computing resources. The applications programs define the way in which these resources are used to solve the computing problems of the users. The operating system controls and coordinates the use of the hardware among the various systems programs and application programs for the various users. We can view an operating system as a resource allocator. A computer system has many resources (hardware and software) that may be required to solve a problem: CPU time, memory space, files storage space, input/output devices etc. The operating system acts as the manager of these resources and allocates them to specific programs and users as necessary for their tasks. Since there may be many, possibly conflicting, requests for resources, the operating system must decide which requests are allocated resources to operate the computer system fairly and efficiently. An operating system is a control program. This program controls the execution of user programs to prevent errors and improper use of the computer. Operating systems exist because: they are a reasonable way to solve the problem of creating a usable computing system. The fundamental goal of a computer system is to execute user programs and solve user problems. While there is no universally agreed upon definition of the concept of an operating system, the following is a reasonable starting point: 7 Operating System : An Overview A computer’s operating system is a group of programs designed to serve two basic purposes: • To control the allocation and use of the computing system’s resources among the various users and tasks, and • To provide an interface between the computer hardware and the programmer that simplifies and makes feasible the creation, coding, debugging, and maintenance of application programs. An effective operating system should accomplish the following functions: • Should act as a command interpreter by providing a user friendly environment. • Should facilitate communication with other users. • Facilitate the directory/file creation along with the security option. • Provide routines that handle the intricate details of I/O programming. • Provide access to compilers to translate programs from high-level languages to machine language • Provide a loader program to move the compiled program code to the computer’s memory for execution. • Assure that when there are several active processes in the computer, each will get fair and non-interfering access to the central processing unit for execution. • Take care of storage and device allocation. • Provide for long term storage of user information in the form of files. • Permit system resources to be shared among users when appropriate, and be protected from unauthorised or mischievous intervention as necessary. Though systems programs such as editors and translators and the various utility programs (such as sort and file transfer program) are not usually considered part of the operating system, the operating system is responsible for providing access to these system resources. The abstract view of the components of a computer system and the positioning of OS is shown in the Figure 1. Figure 1: Abstract View of the Components of a Computer System