What is an operating system?
An operating system (OS) is the program that, after being initially loaded into the computer by a boot program, manages all of the other application programs in a computer. The application programs make use of the operating system by making requests for services through a defined application program interface (API). In addition, users can interact directly with the operating system through a user interface, such as a command-line interface (CLI) or a graphical UI (GUI).
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Why use an operating system?
An operating system brings powerful benefits khổng lồ computer software & software development. Without an operating system, every application would need khổng lồ include its own UI, as well as the comprehensive code needed khổng lồ handle all low-level functionality of the underlying computer, such as disk storage, network interfaces and so on. Considering the vast array of underlying hardware available, this would vastly bloat the form size of every application và make software development impractical.
Instead, many common tasks, such as sending a network packet or displaying text on a standard output đầu ra device, such as a display, can be offloaded khổng lồ system software that serves as an intermediary between the applications và the hardware. The system software provides a consistent & repeatable way for applications lớn interact with the hardware without the applications needing lớn know any details about the hardware.
As long as each application accesses the same resources & services in the same way, that system software -- the operating system -- can service almost any number of applications. This vastly reduces the amount of time và coding required to lớn develop & debug an application, while ensuring that users can control, configure and manage the system hardware through a common and well-understood interface.
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Which also includes:Once installed, the operating system relies on a vast library of device drivers khổng lồ tailor OS services to the specific hardware environment. Thus, every application may make a common call to a storage device, but the OS receives that call & uses the corresponding driver to lớn translate the hotline into actions (commands) needed for the underlying hardware on that specific computer. Today, the operating system provides a comprehensive platform that identifies, configures và manages a range of hardware, including processors; memory devices & memory management; chipsets; storage; networking; port communication, such as clip Graphics Array (VGA), High-Definition Multimedia Interface (HDMI) và Universal Serial Bus (USB); và subsystem interfaces, such as Peripheral Component Interconnect Express (PCIe).
What are the functions of an operating system?
An operating system provides three essential capabilities: It offers a UI through a CLI or GUI; it launches and manages the application execution; and it identifies và exposes system hardware resources lớn those applications -- typically, through a standardized API.
UI. Every operating system requires a UI, enabling users và administrators lớn interact with the OS in order to set up, configure and even troubleshoot the operating system & its underlying hardware. There are two primary types of UI available: CLI and GUI.
The CLI, or terminal mode window, provides a text-based interface where users rely on the traditional keyboard lớn enter specific commands, parameters and arguments related to specific tasks. The GUI, or desktop, provides a visual interface based on icons & symbols where users rely on gestures delivered by human interface devices, such as touchpads, touchscreens & mouse devices.
The GUI is most frequently used by casual or end users that are primarily interested in manipulating files và applications, such as double-clicking a tệp tin icon to xuất hiện the file in its mặc định application. The CLI remains popular among advanced users and system administrators that must handle a series of highly granular & repetitive commands on a regular basis, such as creating và running scripts khổng lồ set up new personal computers (PCs) for employees.
Application management. An operating system handles the launch and management of every application. This typically supports an array of behaviors, including timesharing multiple processes, or threads, so that various tasks can nói qua the available processors" time; handling interruptions that applications produce lớn gain a processor"s immediate attention, ensuring there is enough memory khổng lồ execute the application and its corresponding data without interfering with other processes; carrying out error handling that can gracefully remove an application"s processes; và performing memory management without disrupting other applications or the OS.
An operating system can also support APIs that enable applications to lớn utilize OS and hardware functions without the need to know anything about the low-level OS or hardware state. As an example, a Windows API can enable a program to lớn obtain input from a keyboard or mouse; create GUI elements, such as dialog windows và buttons; read and write files lớn a storage device; và more. Applications are almost always tailored lớn use the operating system on which the application intends to lớn run.
Additionally, an operating system can perform the following services for applications:
In a multitasking operating system, where multiple programs can be running at the same time, the OS determines which applications should run in what order & how much time should be allowed for each application before giving another application a turn.It handles input/output (I/O) to & from attached hardware devices, such as hard disks, printers và dial-up ports.It can offload the management of batch jobs -- for example, printing -- so that the initiating application is freed from this work.On computers that can provide parallel processing, an operating system can manage how lớn divide the program so that it runs on more than one processor at a time.All major computer platforms (hardware và software) require, and sometimes include, an operating system, and operating systems must be developed with different features khổng lồ meet the specific needs of various khung factors.
Device management. An operating system is responsible for identifying, configuring, and providing applications with common access lớn underlying computer hardware devices. As the OS recognizes & identifies hardware, the OS will install corresponding device drivers that enable the OS và applications running on the OS to lớn use the devices without any specific knowledge of the hardware or devices.
An operating system is responsible for identifying the correct printer and installing the appropriate printer drivers so that an application needs to only make calls lớn the printer without having khổng lồ use codes or commands that are specific to lớn that printer -- that is the operating system"s job. The situation is similar for other devices, such as USB ports; networking ports; graphics devices, such as graphics processing units (GPUs); motherboard chipsets; và storage devices, such as Serial-Attached SCSI (SAS) disk adapters và disks that are formatted with a suitable tệp tin system.
The OS identifies and configures physical và logical devices for service & typically records them in a standardized structure, such as Windows Registry. Device manufacturers periodically patch and update drivers, & the OS should update them khổng lồ ensure best device performance & security. When devices are replaced, the OS also installs & configures new drivers.
Operating system types and examples
Although the fundamental roles of an operating system are ubiquitous, there are countless operating systems that serve a wide range of hardware và user needs.
General-purpose operating system. A general-purpose OS represents an array of operating systems intended to run a multitude of applications on a broad selection of hardware, enabling a user khổng lồ run one or more applications or tasks simultaneously. A general-purpose OS can be installed on many different desktop and laptop models & run applications from accounting systems to lớn databases to lớn web browsers lớn games. General-purpose operating systems typically focus on process (thread) và hardware management khổng lồ ensure that applications can reliably giới thiệu the wide range of computing hardware present.
Common desktop operating systems include the following:
Mac OS is the operating system for Apple"s Macintosh line of PCs và workstations.Mobile operating system. di động operating systems are designed to accommodate the quality needs of smartphone computing & communication-centric devices, such as smartphones and tablets. Thiết bị di động devices typically offer limited computing resources compared to traditional PCs, and the OS must be scaled back in size and complexity in order to minimize its own resource use, while ensuring adequate resources for one or more applications running on the device. Thiết bị di động operating systems tend to emphasize efficient performance, user responsiveness and close attention lớn data handling tasks, such as supporting media streaming. Táo bị cắn i
OS & Google game android are examples of mobile operating systems.
Embedded operating system. Not all computing devices are general purpose. A huge assortment of dedicated devices -- including trang chủ digital assistants, automated teller machines (ATMs), airplane systems, retail point of sale (POS) terminals và internet of things (Io
T) devices -- includes computers that require an operating system. The principal difference is that the associated computing device only does one major thing, so the OS is highly stripped down & dedicated khổng lồ both performance and resilience. The OS should run quickly, not crash, và handle all errors gracefully in order to continue operating in all circumstances. In most cases, the OS is provided on a chip that is incorporated into the actual device. A medical device used in a patient"s life support equipment, for example, will employ an embedded OS that must run reliably in order khổng lồ keep the patient alive. Embedded Linux is one example of an embedded OS.
Network operating system. A network operating system (NOS) is another specialized OS intended lớn facilitate communication between devices operating on a local area network (LAN). A NOS provides the communication stack needed lớn understand network protocols in order khổng lồ create, exchange và decompose network packets. Today, the concept of a specialized NOS is largely obsolete because other OS types largely handle network communication. Windows 10 và Windows hệ thống 2019, for example, include comprehensive networking capabilities. The concept of a NOS is still used for some networking devices, such as routers, switches và firewalls, and manufacturers may employ proprietary NOSes, including Cisco Internetwork Operating System (IOS), Router
OS và Zy
NOS.
Real-time operating system. When a computing device must interact with the real world within constant & repeatable time constraints, the device manufacturer may opt lớn use a real-time operating system (RTOS). For example, an industrial control system may direct the operations of a sprawling factory or nguồn plant. Such a facility will produce signals from myriad sensors & also send signals khổng lồ operate valves, actuators, motors & countless other devices. In these situations, the industrial control system must respond quickly và predictably khổng lồ changing real-world conditions -- otherwise, disaster may result. An RTOS must function without buffering, processing latencies and other delays, which are perfectly acceptable in other types of operating systems. Two examples of RTOSes include Free
RTOS và Vx
Works.
The differences between operating system types are not absolute, and some operating systems can nói qua characteristics of others. For example, general-purpose operating systems routinely include the networking capabilities found in a traditional NOS. Similarly, an embedded operating system commonly includes attributes of an RTOS, while a mobile operating system can still typically run numerous apps simultaneously lượt thích other general-purpose operating systems.
An Operating System (OS) is an interface between a computer user và computer hardware. An operating system is a software which performs all the basic tasks lượt thích file management, memory management, process management, handling input và output, and controlling peripheral devices such as disk drives & printers.An operating system is software that enables applications to interact with a computer"s hardware. The software that contains the core components of the operating system is called the kernel.
The primary purposes of an Operating System are khổng lồ enable applications (spftwares) khổng lồ interact with a computer"s hardware & to manage a system"s hardware & software resources.
Some popular Operating Systems include Linux Operating System, Windows Operating System, VMS, OS/400, AIX, z/OS, etc. Today, Operating systems is found almost in every device like mobile phones, personal computers, mainframe computers, automobiles, TV, Toys etc.
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Definitions
We can have a number of definitions of an Operating System. Let"s go through few of them:
An Operting System is the low-level software that supports a computer"s basic functions, such as scheduling tasks and controlling peripherals.We can refine this definition as follows:
An operating system is a program that acts as an interface between the user & the computer hardware and controls the execution of all kinds of programs.Following is another definition taken from Wikipedia:
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.Architecture
We can draw a generic architecture diagram of an Operating System which is as follows:
Operating System Generations
Operating systems have been evolving over the years. We can categorise this evaluation based on different generations which is briefed below:
0th Generation
The term 0th generation is used to lớn refer to lớn the period of development of computing when Charles Babbage invented the Analytical Engine và later John Atanasoff created a computer in 1940. The hardware component công nghệ of this period was electronic vacuum tubes. There was no Operating System available for this generation computer and computer programs were written in machine language. This computers in this generation were inefficient và dependent on the varying competencies of the individual programmer as operators.
First Generation (1951-1956)
The first generation marked the beginning of commercial computing including the introduction of Eckert và Mauchly’s UNIVAC I in early 1951, and a bit later, the IBM 701.
System operation was performed with the help of expert operators and without the benefit of an operating system for a time though programs began to lớn be written in higher level, procedure-oriented languages, and thus the operator’s routine expanded. Later mono-programmed operating system was developed, which eliminated some of the human intervention in running job and provided programmers with a number of desirable functions. These systems still continued khổng lồ operate under the control of a human operator who used lớn follow a number of steps to lớn execute a program. Programming language lượt thích FORTRAN was developed by John W. Backus in 1956.
Second Generation (1956-1964)
The second generation of computer hardware was most notably characterised by transistors replacing vacuum tubes as the hardware component technology. The first operating system GMOS was developed by the IBM computer. GMOS was based on single stream batch processing system, because it collects all similar jobs in groups or batches & then submits the jobs khổng lồ the operating system using a punch card to complete all jobs in a machine. Operating system is cleaned after completing one job và then continues to read và initiates the next job in punch card.
Researchers began to lớn experiment with multiprogramming & multiprocessing in their computing services called the time-sharing system. A noteworthy example is the Compatible Time Sharing System (CTSS), developed at MIT during the early 1960s.
Third Generation (1964-1979)
The third generation officially began in April 1964 with IBM’s announcement of its System/360 family of computers. Hardware giải pháp công nghệ began khổng lồ use integrated circuits (ICs) which yielded significant advantages in both speed và economy.
Operating system development continued with the introduction & widespread adoption of multiprogramming. The idea of taking fuller advantage of the computer’s data channel I/O capabilities continued lớn develop.
Another progress which leads to developing of personal computers in fourth generation is a new development of minicomputers with DEC PDP-1. The third generation was an exciting time, indeed, for the development of both computer hardware and the accompanying operating system.
Fourth Generation (1979 – Present)
The fourth generation is characterised by the appearance of the personal computer & the workstation. The component công nghệ of the third generation, was replaced by very large scale integration (VLSI). Many Operating Systems which we are using today lượt thích Windows, Linux, Mac
OS etc developed in the fourth generation.
Following are some of important functions of an operating System.
Memory ManagementProcessor Management
Device Management
File Management
Network Management
Security
Control over system performance
Job accounting Error detecting aids
Coordination between other software và users
Memory Management
Memory management refers khổng lồ management of Primary Memory or Main Memory. Main memory is a large array of words or bytes where each word or byte has its own address.
Main memory provides a fast storage that can be accessed directly by the CPU. For a program lớn be executed, it must in the main memory. An Operating System does the following activities for memory management −
Keeps tracks of primary memory, i.e., what part of it are in use by whom, what part are not in use.
In multiprogramming, the OS decides which process will get memory when & how much.
Allocates the memory when a process requests it to vì so.
De-allocates the memory when a process no longer needs it or has been terminated.
Processor Management
In multiprogramming environment, the OS decides which process gets the processor when và for how much time. This function is called process scheduling. An Operating System does the following activities for processor management −
Keeps tracks of processor & status of process. The program responsible for this task is known as traffic controller.
Allocates the processor (CPU) lớn a process.
De-allocates processor when a process is no longer required.
Device Management
An Operating System manages device communication via their respective drivers. It does the following activities for device management −
Keeps tracks of all devices. Program responsible for this task is known as the I/O controller.
Decides which process gets the device when and for how much time.
Allocates the device in the efficient way.
De-allocates devices.
File Management
A tệp tin system is normally organized into directories for easy navigation and usage. These directories may contain files and other directions.
An Operating System does the following activities for file management −
Keeps track of information, location, uses, status etc. The collective facilities are often known as file system.
Decides who gets the resources.
Allocates the resources.
De-allocates the resources.
Other Important Activities
Following are some of the important activities that an Operating System performs −
Security − By means of password và similar other techniques, it prevents unauthorized access khổng lồ programs and data.
Control over system performance − Recording delays between request for a service và response from the system.
Job accounting − Keeping track of time and resources used by various jobs and users.
Error detecting aids − Production of dumps, traces, error messages, và other debugging & error detecting aids.
Coordination between other softwares and users − Coordination và assignment of compilers, interpreters, assemblers and other software lớn the various users of the computer systems.
