What is Operating System (OS)?

What is Operating System (OS)?

26 June 2023 0 By Anshul Pal

An operating system is a collection of system programs that together controls the operations of a computer system. Operating system is a program,(or a system program) that, after being initially loaded into the computer by a boot program, manages all other program in a computer. The other programs managed by it are usually application programs.

It manages all the resources of the computer. Operating System is a program that acts as an intermediary between a user of a computer hardware. Operating system is that which interact with the software and the hardware. The software is the non-touchable part of the computer used for making an application, while hardware are those which is used for performing an operation. The purpose of an Operating System is to provide an environment in which a user can execute programs in a convenient and efficient manner.

Example : The most common operating systems are the windows family of operating systems (Windows 95, 98, 2000, NT), the Unix family of operating systems (which includes Linux, BSD UNIX and many other derivatives ) and the Macintosh operating system. Many operating systems are available for special purposes applications including specializations for mainframes, robotics, manufacturing, real-time control systems and so on.

History of Operating System

Functions of an Operating System

The main functions of operating system are as follows :

  1. Process Management : The OS is responsible for the following process management activities :
    • The creation and deletion of both user and system processes.
    • The scheduling of process.
    • The mechanism of synchronization and communication.
    • Deadlock handling for processes.
  2. Memory Management : The memory management module of an operating system takes care of the following things :
    • Allocation of Memory : It is concerned with allocation of physical memory of finite capacity. No process may be activated before a certain amount of memory can be allocated to it.
    • Deallocation of Memory : Temporarily inactive processes may be swapped out of memory to make room for other processes.
  3. File Management : The file management module of an operating system is charged with managing data that reside on secondary storage. Its common responsibilities are :
    • Mapping of access request form logical to physical file address space.
    • Transmission of file elements between main and secondary storage.
    • Management of secondary storage, such as keeping track of the status, allocation and deallocation of space.
    • Support for protection and sharing of files and the recovery and possible restoration of files after system crashes.
  4. Device Management : One of the function of an OS is to hide the peculiarities of specific hardware devices form the user. It takes care of :
    • Controlling all the computer’s Input Output devices.
    • Input Output requests from processes and issues commands to the input output devices.
    • It ensures correct data transmission to/from Input Output device.
  5. Security : The primary objective of operating systems and of the systems software is to provide a flexible and functionally complete set of security mechanism in order to enable users and owners of information to enforce security policies as they see fit.
  6. Disk Management : The main purpose of a computer system is to execute programs. These programs, with the data they access, must be in main memory or primary storage during execution. The OS is responsible for the following activities in connection with disk management :
    • Free Space Management
    • Storage allocation
    • Disk scheduling
  7. Command Interpretation : One of the most important system programs for an operating system is the command interpreter which  is the interface between the user and the OS. Many commands are given to the OS by control statements. The command interpretation module of an OS takes care of :
    • Interpreting user commands.
    • Directing the system resources to handle the requests.

Importance of Operating System

An Operating System is the infrastructure/ software component of a computer system. It is responsible for the management and coordination of activities and the sharing of the limited resources of the computer. The Operating System acts as a host for application that run on the machine. As a host, one of the purposes of an Operating System is to handle the details of the operations of the hardware. This relieves applications programs from having to manage these details and makes it easier to write applications. Almost all computers including hand held computers, desktop computer, supercomputers and even video game console use an Operating System of Some type. Some of the oldest models may however use an embedded operating system, that may be contained on a compact disk or other data storage device. Without an operating system, computer is dummy.

An operating system is a program that controls the execution of an application program and acts as an interface between the user of a computer and computer hardware. The purpose of an OS is to provide an environment in which a user can execute a program in a convenient and efficient manner.

Purposes of an Operating System

  1. Convenience : An operating system makes a computer more convenient to use.
  2. Efficiency : An operating system allows the computer system resources to be used in an efficient manner.
  3. Ability to Solve : An OS should be constructed in such a way as to permit the effective development, testing and introduction of new system functions without interfering with current services provided.
  4. Resource Allocator : Computer system has many resources i.e. Hardware and Software, CPU, Memory space etc. Operating system acts as the manager of these resources and allocates them to specific program and users to perform specific tasks.
  5. Control Program : Operating System acts as a control program that controls the execution of user program to prevent errors and improper use of the computer.

Role of an Operating System

  1. As a Process Manager : A process is a program in execution. During its execution, a process needs certain resources such as CPU time, memory space, files and input output devices etc. At a particular instance of time, a computer system normally consists of a collection of processes. The process management module of an operating system takes care of the creation and deletion of processes, scheduling of various system resources to the different processes requesting them and providing mechanisms for synchronization and communication among processes.
  2. As a Memory Manager : To execute a program, it must be loaded together with the data it accesses in the main memory ( at least partially ). To improve CPU utilization and to provide better response time to its users, a computer system normally keeps several programs in main memory. The memory management module of an operating system takes care of the allocation and deallocation of memory space to the various programs in need of this resources.
  3. As a File Manager : All computer systems are used for storage, retrieval and sharing of information. A computer normally stores such information in units called files. Processes can read information form files for storing newly generated information. Information stores in files is made persistent by storing them on a secondary storage media such as a magnetic disk. Files provide a natural and easy means of information sharing. That is, a file can be created by one application and then shared with different applications at a later time. The file management module of an operating system takes care of file-related activities such as organization, storing retrieval, naming sharing and protection of files. It allows programs to use asset of operations that characterize the file abstraction and free the programmers from concerns about the details of space allocations and layout of the secondary storage device.
  4. As a Device Manager : A computer system normally consists of several I/O devices such as terminal, printer, disk and tape. The device management module of an operating system take care of controlling all the computer’s I/O devices. It keeps track of I/O requests from processes, issues commands to the input output devices and ensures correct data transmission to/from I/O device. It also provides an interface between the device and the rest of the system to make it simple and easy to use. Often, this interface is same for all types of I/O devices.
  5. Security : Computer systems often store large amounts of information, some of which is highly sensitive and valuable to their users. Users can trust the system and rely on it, only, if the various resources and information of a computer system are protected against destruction and unauthorized access. The security module of an OS ensures that when several disjoint processes are being executed simultaneously, one process does not interface with the other or with the OS itself.
  6. As a Command Interpreter : A user communicates with the operating system, for using the various system resources, via a set of commands provided by the operating system. The operating system also provides a simple language, known as Command Language (CL) or Job Control Language (JCL) using which a user can put several commands together from the command set to describe the resource requirements of the job. The command supplied individually or in the form of command language and directing the system resources to handle the requests. With this mode of interaction with the system, the user is usually not too concerned with the hardware details of the system or with how the OS will direct the hardware to handle certain requests.

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