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2.1: Introduction to Operating Systems

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    Introduction to Operating System

    An operating system acts as an intermediary between the user of a computer and computer hardware. The purpose of an operating system is to provide an environment in which a user can execute programs in a convenient and efficient manner.

    An operating system is a software that manages the computer hardware. The hardware must provide appropriate mechanisms to ensure the correct operation of the computer system and to prevent user programs from interfering with the proper operation of the system.

    Operating System


    • An operating system is a program that controls the execution of application programs and acts as an interface between the user of a computer and the computer hardware.
    • A more common definition is that the operating system is the one program running at all times on the computer (usually called the kernel), with all else being application programs.
    • An operating system is concerned with the allocation of resources and services, such as memory, processors, devices, and information. The operating system correspondingly includes programs to manage these resources, such as a traffic controller, a scheduler, memory management module, I/O programs, and a file system.

    Functions of Operating system

    Operating system performs three functions:

    1. Convenience: An OS makes a computer more convenient to use.
    2. Efficiency: An OS allows the computer system resources to be used in an efficient manner.
    3. Ability to Evolve: An OS should be constructed in such a way as to permit the effective development, testing and introduction of new system functions at the same time without interfering with service.

    Operating system as User Interface –

    1. User
    2. System and application programs
    3. Operating system
    4. Hardware

    Every general-purpose computer consists of the hardware, operating system, system programs, and application programs. The hardware consists of memory, CPU, ALU, and I/O devices, peripheral device, and storage device. System program consists of compilers, loaders, editors, OS, etc. The application program consists of business programs, database programs.

    The operating system sits between the hardware and the application programs which are run by the user. It is the interface between the applications and the hardware

    Figure \(\PageIndex{1}\): Conceptual view of a computer system ("Conceptual view of a computer system" by Unknown, Geeks for Geeks is licensed under CC BY-SA 4.0)

    Every computer must have an operating system to run other programs. The operating system coordinates the use of the hardware among the various system programs and application programs for various users. It simply provides an environment within which other programs can do useful work.

    The operating system is a set of special programs that run on a computer system that allows it to work properly. It performs basic tasks such as recognizing input from the keyboard, keeping track of files and directories on the disk, sending output to the display screen and controlling peripheral devices.
    OS is designed to serve two basic purposes:

    1. It controls the allocation and use of the computing System’s resources among the various user and tasks.
    2. It provides an interface between the computer hardware and the programmer that simplifies and makes feasible for coding, creation, debugging of application programs.

    The Operating system must support the following tasks. The task are:

    1. Provides the facilities to create, modification of programs and data files using an editor.
    2. Access to the compiler for translating the user program from high level language to machine language.
    3. Provide a loader program to move the compiled program code to the computer’s memory for execution.
    4. Provide routines that handle the details of I/O programming.

    I/O System Management

    One of the important jobs of an Operating System is to manage the operations of various I/O devices including mouse, keyboards, touch pad, disk drives, display adapters, USB devices, Bit-mapped screen, LED, Analog-to-digital converter, On/off switch, network connections, audio I/O, printers etc.

    The I/O system of an OS works by taking I/O request from an application software and sending it to the physical device, which could be an input or output device then it takes whatever response comes back from the device and sends it to the application.

    Components of I/O Hardware

    • I/O Device
    • Device Driver
    • Device Controller

    I/O Device:

    I/O devices such as storage, communications, user-interface, and others communicate with the computer via signals sent over wires or through the air. Devices connect with the computer via ports, e.g. a serial or parallel port. A common set of wires connecting multiple devices is termed a bus.

    I/O devices can be divided into two categories:

    • Block devices − A block device is one with which the device driver communicates by sending entire blocks of data. For example, Hard disks, USB cameras, Disk-OnKey etc.
    • Character devices − A character device is one with which the device driver communicates by sending and receiving single characters (bytes, octets). For example, serial ports, parallel ports, sounds cards etc

    Device Driver: Device drivers are software modules that can be plugged into an OS to handle a particular device. Operating System takes help from device drivers to handle all I/O devices.

    Device Controller: The Device Controller works like an interface between a device and a device driver. I/O units (Keyboard, mouse, printer, etc.) typically consist of a mechanical component and an electronic component where electronic component is called the device controller. 

    History of Operating system

    Operating system has been evolving through the years. Following Table shows the history of OS.

    Generation Year Electronic device used Types of OS Device
    First 1945-55 Vacuum Tubes Plug Boards
    Second 1955-65 Transistors Batch Systems
    Third 1965-80 Integrated Circuits(IC) Multiprogramming
    Fourth Since 1980 Large Scale Integration PC


    This page titled 2.1: Introduction to Operating Systems is shared under a CC BY-SA license and was authored, remixed, and/or curated by Patrick McClanahan.