What is an operating system? Types of operating systems.  What is an operating system

Annotation: Operating system functions. Operating system structure. Classification of operating systems. Operating system requirements.

operating system(operating system) - a set of programs that provides the user with a convenient environment for working with computer equipment.

operating system allows you to run user programs; manages all resources computer system– processor(s), RAM, input/output devices; provides long-term storage of data in the form of files on external memory devices; provides access to computer networks.

To more fully understand the role of the operating system, consider the components of any computing system(Fig. 1.1).

Rice. 1.1.

All components can be divided into two large classes - programs or software(software) and equipment or hardware(hardware). Software divided into applied, instrumental and systemic. Let's briefly consider each type of software.

The purpose of creating a computing system is to solve user problems. To solve a certain range of problems, an application program (application, application) is created. Examples application programs are text editors and processors (Notepad, Microsoft Word), graphic editors (Paint, Microsoft Visio), spreadsheets (Microsoft Excel), database management systems (Microsoft Access, Microsoft SQL Server), browsers (Internet Explorer), etc. The entire set of application programs is called application software ( application software).

Created software using a variety of programming tools (development environments, compilers, debuggers, etc.), the totality of which is called instrumental software. The representative of the tool software is development environment Microsoft Visual Studio.

The main types of system software are operating systems. Their main task is to provide an interface (way of interaction) between the user and applications on the one hand, and hardware on the other. System software also includes system utilities– programs that perform a strictly defined function to maintain a computer system, for example, diagnose system state, defragment files on the disk, and compress (archive) data. Utilities may be included with the operating system.

The interaction of all programs with the operating system is carried out using system calls - requests from programs for the operating system to perform the necessary actions. A set of system calls forms the API - Application Programming Interface.

Operating system features

The main functions performed by operating systems include:

• ensuring program execution - loading programs into memory, providing programs with processor time, processing system calls;
• RAM management – ​​efficient allocation of memory to programs, accounting for free and used memory;
• external memory management – ​​support for various file systems;
• I/O management – ​​ensuring work with various peripheral devices;
• providing a user interface;
• ensuring security – protecting information and other system resources from unauthorized use;
• organization of network interaction.

Operating system structure

Before studying the structure of operating systems, you should consider the operating modes of processors.

Modern processors have at least two operating modes - privileged (supervisor mode) and user (user mode).

The difference between them is that in user mode, processor commands related to hardware management, RAM protection, and switching processor operating modes are not available. In privileged mode, the processor can execute all possible commands.

Applications running in user mode cannot directly access each other's address spaces - only through system calls.

All components of the operating system can be divided into two groups - those running in privileged mode and those running in user mode, and the composition of these groups varies from system to system.

The main component of the operating system is the kernel. Kernel functions may vary significantly depending on the different systems; but on all systems the kernel runs in privileged mode (often called kernel mode).

The term "core" is also used in different senses. For example, in Windows, the term “kernel” (NTOS kernel) refers to a combination of two components - the executive system (executive layer) and the kernel itself (kernel layer).

There are two main types of kernels - monolithic kernels and microkernels. The monolithic kernel implements all the main functions of the operating system, and it is, in fact, a single program, which is a collection of procedures. In the microkernel there remains only a minimum of functions that must be implemented in privileged mode: thread scheduling, interrupt handling, interprocess communication. The remaining functions of the operating system for managing applications, memory, security, etc. are implemented in the form of separate modules in user mode.

Kernels that occupy an intermediate position between monolithic and microkernels are called hybrid kernels.

Examples of different types of kernels:

• monolithic kernel – MS-DOS, Linux, FreeBSD;
• microkernel – Mach, Symbian, MINIX 3;
• hybrid kernel – NetWare, BeOS, Syllable.

Discussion of what type it is Windows kernel NT, given in [; ]. It is said that Windows NT has a monolithic kernel, however, since Windows NT has several key components that run in user mode (for example, environment subsystems and system processes - see Lecture 4 "Windows Architecture"), then Windows NT It is impossible to refer to truly monolithic kernels, but rather to hybrid ones.

In addition to the kernel, drivers operate in privileged mode (in most operating systems) - software modules, controlling devices.

The operating system also includes:

• system libraries (system DLL - Dynamic Link Library, dynamic link library) that convert application system calls into kernel system calls;
• user shells that provide the user with an interface - convenient way working with the operating system.

User shells implement one of two main types of user interface:

• text interface (Text User Interface, TUI), other names – console interface (Console User Interface, CUI), interface command line(Command Line Interface, CLI);
• GUI(Graphic User Interface, GUI).

An example of implementing a text interface in Windows is the command line interpreter cmd.exe; GUI example - Windows Explorer(explorer.exe).

Classification of operating systems

Operating systems can be classified in several ways.

1. According to the method of organizing calculations:
   • systems batch processing(batch processing operating systems) – the goal is to perform the maximum number of computing tasks per unit of time; in this case, a package is formed from several tasks, which is processed by the system;
   • time-sharing operating systems – the goal is to allow multiple users to use one computer simultaneously; implemented by alternately providing each user with an interval of processor time;
   • real-time operating systems – the goal is to complete each task within a strictly defined time interval for a given task.
2. By kernel type:
   • systems with a monolithic core (monolithic operating systems);
   • microkernel operating systems;
   • systems with a hybrid core (hybrid operating systems).
3. By the number of simultaneously solved tasks:
   • single-tasking operating systems;
   • multitasking operating systems.
4. By the number of concurrent users:
   • single-user operating systems;
   • multi-user operating systems.
5. By number of supported processors:
   • single-processor operating systems;
   • multiprocessor operating systems.
6. For network support:
   • local operating systems – autonomous systems, not intended for use on a computer network;
   • network operating systems – systems that have components that allow you to work with computer networks.
7. By role in network interaction:
   • server operating systems – operating systems that provide access to network resources and manage the network infrastructure;
   • client operating systems – operating systems that can access network resources.
8. By license type:
   • open-source operating systems – operating systems with open source code, available for study and change;
   • proprietary operating systems – operating systems that have a specific copyright holder; usually come with closed source code.
9. By area of ​​application:
   • operating systems of mainframes - large computers (mainframe operating systems);
   • server operating systems;
   • personal computer operating systems;
   • operating systems mobile devices(mobile operating systems);
   • embedded operating systems;
   • router operating systems.

Operating system requirements

The main requirement for modern operating systems is to perform the functions listed above in the paragraph “Functions of operating systems”. In addition to this obvious requirement, there are others, often no less important:

• extensibility – the ability of the system to acquire new functions in the process of evolution; often implemented by adding new modules;
• portability – the ability to transfer the operating system to another hardware platform with minimal changes;
• compatibility – ability to work together; compatibility may occur new version operating system with applications written for old version, or compatibility of different operating systems in the sense that applications for one of these systems can be run on another and vice versa;
• reliability - probability trouble-free operation systems;
• performance – the ability to provide acceptable problem solving time and system response time.

Resume

This lecture provides a definition of an operating system, introduces types of software, and discusses the functions and structure of an operating system. Particular attention is paid to the concept of "core". Also given are various ways of classifying operating systems and the requirements for modern operating systems.

The next lecture will provide an overview of operating systems Microsoft Windows.

Security questions

1. Define the term "operating system".
2. Name examples of application, instrumental and system software.
3. Define the concepts " system call", "API", "driver", "kernel".
4. What types of kernels do you know? What types of operating system kernels do you know?
5. How is a kernel different from an operating system?
6. Give several ways to classify operating systems.
7. Name the requirements for modern operating systems and explain what they mean.

It is a set of interconnected programs that acts as an interface between applications and users on the one hand, and hardware on the other. According to this definition, the OS performs two groups of functions.
- providing the user or programmer, instead of real computer hardware, with an extended virtual machine, which is more convenient to work with and easier to program;
- increasing the efficiency of using a computer by rationally managing its resources in accordance with certain criteria.
An operating system (OS) is a program that is designed to manage all the physical and logical resources of a computer and is capable of creating an interface between the user and the computer.
The operating system is designed to control the execution of user programs, schedule and manage computing resources.
Operating systems for personal computers are divided into:
1. Single- and multi-tasking (depending on the number of parallel running application processes);
2. Single and multi-user (depending on the number of users simultaneously working with the operating system);
3. Non-portable and portable to other types of computers;
4. Non-network and network, providing work in a local area network.
OS examples: MS DOS, Windows 98/2000, Windows XP, Lunix, etc.

Purpose of operating systems

An operating system is a complex of interconnected system programs, the purpose of which is to organize the interaction of the user with the computer, to manage the resources of the computer system in order to use them most efficiently. The operating system acts as a link between the computer hardware, on the one hand, and the programs being executed, as well as the user, on the other hand. The operating system can be called a software extension of the computer's control device. The operating system hides complex unnecessary details of hardware control from the user, forming a layer between them, as a result of which people are freed from the very labor-intensive work of organizing interaction with computer hardware.

The main requirement for an operating system is the complex task of organizing an effective sharing resources by several processes, and this complexity is generated mainly by the random nature of requests for resource consumption. In a multiprogram system, queues of requests are formed from simultaneously running programs to shared computer resources: processor, memory page, printer, disk. The operating system organizes servicing of these queues using different algorithms: first-come, first-served, priority-based, round-robin, etc.

A modern OS typically must support multi-program processing, virtual memory, a multi-window graphical user interface, and many other necessary functions and services. In addition to these requirements for functional completeness, operating systems are subject to equally important operational requirements:

· Extensibility. While computer hardware becomes obsolete within a few years, useful life operating systems can be measured in decades. Therefore, operating systems always change evolutionarily over time, and these changes are more significant than hardware changes. Changes to the OS usually involve the acquisition of new properties, such as support for new types of external devices or new network technologies. If the OS code is written in such a way that additions and changes can be made without violating the integrity of the system, then such an OS is called extensible. Extensibility is achieved through the modular structure of the OS, in which programs are built from a set of individual modules that interact only through functional interface;

· Portability. Ideally, OS code should be easily portable from one type of processor to another type of processor, and from one type of hardware platform (which differs not only in the processor type, but also in the way the entire computer hardware is organized) to another type of hardware platform. Portable operating systems have several implementation options for different platforms; this property of an operating system is also called multi-platform;

· Compatibility. There are several “long-lived” popular operating systems for which a wide range of applications have been developed. Some of them are widely popular. Therefore, for a user switching from one OS to another for one reason or another, the opportunity to run a familiar application on the new operating system is very attractive. If an OS has the means to run application programs written for other operating systems, then it is said to be compatible with these operating systems. A distinction must be made between binary compatibility and source compatibility. The concept of compatibility also includes support for user interfaces of other operating systems;

· Reliability and fault tolerance. The system must be protected from both internal and external errors, failures and failures. Its actions should always be predictable, and applications should not be able to harm the OS. The reliability and fault tolerance of an OS are primarily determined by the architectural solutions underlying it, as well as the quality of its implementation (debuggedness of the code). In addition, it is important whether the OS includes software support for hardware fault tolerance, such as disk arrays or sources uninterruptible power supply;

· Safety. A modern OS must protect data and other computer system resources from unauthorized access. In order for an OS to have security properties, it must at least have a means of determining the legality of users, providing legal users with differentiated access rights to resources, and also be able to record all events “suspicious” for the security of the system. The security property is especially important for network operating systems. In such OSs, the task of protecting data transmitted over the network is added to the task of access control;

· Productivity. The operating system must have such good performance and response time, as far as the hardware platform allows. The performance of the OS is influenced by many factors, among which the main ones are the OS architecture, variety of functions, quality of code programming, ability to run the OS on a high-performance (multiprocessor) platform;
Process management

The most important part of the operating system, directly affecting the functioning computer, is a process management system. For each newly created process, the OS generates system information structures, assigns it an area of ​​RAM in which the process codes and data will be located, and also provides it with the required amount of processor time. Since processes often simultaneously apply for the same resources, the OS’s responsibilities include maintaining queues of processes’ requests for resources and synchronizing them, for example, queues for the processor, for the printer, for serial port, suspending execution until an event occurs in the system.

Memory management

OS memory management functions include tracking free and used memory; allocates memory to processes and releases memory when processes terminate; memory protection; displacing processes from RAM to disk and returning them to RAM, as well as setting program addresses to a specific area physical memory. Memory is the same for the process important resource, like a processor, since a process can only be executed by a processor if its codes and data are in RAM.

Manage files and external devices

The ability of the OS to “shield” the complexities of real hardware is very clearly manifested in one of the main subsystems of the OS - file system. The operating system creates a virtual set of data stored on an external drive in the form of a file - a simple unstructured sequence of bytes with a symbolic name. For convenience of working with data, files are grouped into directories, which, in turn, form groups - directories of more high level. Using the OS, the user can perform actions on files and directories such as searching by name, deleting, displaying contents on external device(for example, to a display), changing and saving content.
Data protection and administration

An important means of data protection are the OS audit functions, which consist in recording all events on which the security of the system depends.

Basic classifications of operating systems

Operating systems may differ in the implementation features of internal algorithms for managing the main computer resources (processors, devices, memory), features of the design methods used, types of hardware platforms, areas of use and many other properties.

There are several classifications of operating systems, which highlight certain criteria that reflect various essential characteristics of systems; let’s look at the most common ones:

By purpose

1. General purpose systems.

It implies an OS designed to solve a wide range of tasks, including launching various applications, developing and debugging programs, working with the network and multimedia.

2. Real-time systems.

Designed to work in the object control loop.

Other specialized systems.

These are different operating systems, aimed primarily at effective solution a certain class, with greater or lesser damage to other tasks

By the nature of user interaction

1.Batch OSes that process pre-prepared jobs

2.Conversational operating systems that perform user tasks interactively

GUI OS

Embedded OS with no user interaction

By the number of simultaneous tasks

1.Single-tasking OS.

In such systems, no more than one user process can exist at any given time. However, at the same time, system processes may be running

Multitasking OS.

They provide parallel execution of some user processes. The implementation of multitasking requires a significant complication of the algorithms and data structures used in the system.

By number of simultaneous users

1.Single-user OS.

They are characterized by full user access to resources. Such systems are acceptable mainly on isolated computers.

2.Multi-user OS.

Their an important component are means of protecting the data and processes of each user, based on the concept of the owner of the resource and on the precise indication of access rights granted to each user of the system.

By hardware basis

1.Single-processor OS.

2.Multiprocessor OS.

The tasks of such a system include the efficient distribution of executed tasks among processors and the organization of coordinated operation of all processors.

3.Network OS.

They include the ability to access other computers local network, working with file and other servers.

4.Distributed operating systems.

A distributed system, using local network resources, presents them to the user as unified system, not divided into separate machines.

By construction method

1.Micronuclear

2. Monolithic

Classification of operating systems by families

OPERATING SYSTEMS, THEIR PURPOSE AND VARIETIES

An operating system (OS) is a set of programs that perform two main functions: providing the user with the convenience of a virtual machine and increasing the efficiency of using a computer while rationally managing its resources.

A virtual machine is the functional equivalent of an imaginary computer with a given configuration, modeled by the software and hardware of a real computer. The OS hides from the user the features of the physical location of information on disks and handles interrupts (termination of the computing process caused by requests for servicing other devices), manages timers and RAM. As a result, the user is provided with a virtual machine that implements work at the logical level.

The following requirements apply to modern operating systems:

• compatibility - the OS must include tools for running applications prepared for other operating systems;
• portability - ensuring the ability to transfer the OS from one hardware platform to another;
• reliability and fault tolerance - involves protecting the OS from internal and external errors, failures and failures;
• security - the OS must contain means to protect the resources of some users from others;
• extensibility - the OS should provide ease of making subsequent changes and additions;
• performance - the system must have sufficient speed.

Based on the number of simultaneously performed tasks, single-tasking operating systems (MS DOS, early versions PC DOS) and multitasking (OS/2, UNIX, Windows).

Single-tasking operating systems provide the user with virtual machine and include file management, peripheral device management, and user communication tools. Multitasking OSes additionally manage the division of shared resources between tasks. Multitasking can be non-preemptive (NetWare, Windows 3/95/98) or preemptive (Windows NT, OS/2, UNIX). In the first case active process upon completion, it transfers control to the OS to select another process from the queue. In the second, the decision to switch the processor from one process to another is made by the OS.

Based on the number of simultaneously working users, operating systems are divided into single-user (MS DOS, Windows 3x, early versions of OS/2) and multi-user (UNIX, WINDOWS NT). Multi-user systems contain means to protect user information from unauthorized access.

The network OS contains means of transmitting data between computers over communication lines and implementing data transfer protocols.

In addition to OSes focused on a specific type of hardware platform, there are mobile OSs that are easily portable to different types of computers (UNIX). In such OSs, hardware-dependent locations are localized and are rewritten when the system is transferred. The hardware-independent part is implemented in a high-level programming language, usually C, and is recompiled when. moving to another platform.

IN present moment about 90% of computers use Windows OS. A broader class of OS is targeted for use on servers. This class of OS includes the UNIX family, Microsoft developments (MS DOS and Windows), Novell network products and IBM Corporation.

UNIX - multi-user, multi-tasking OS, includes quite powerful means of protecting programs and files of various users. The UNIX OS is machine-independent, which ensures high OS mobility and easy portability of application programs to computers of different architectures. An important feature of the UNIX family OS is its modularity and extensive set of service programs, which make it possible to create a favorable operating environment for user programmers (that is, the system is especially effective for specialists - application programmers).

Regardless of the version, the common features of UNIX are a multi-user mode with means of protecting data from unauthorized access; implementation of multitasking processing in time sharing mode; portability of the system by writing the main part in C language.

The disadvantage of UNIX is its high resource consumption, and for small single-user systems based on personal computers it is most often redundant.

In general, UNIX family operating systems are aimed primarily at large local (corporate) and global networks, uniting the work of thousands of users. The widespread use of UNIX and its LINUX version received on the Internet, where machine independence of the OS is of utmost importance.

MS DOS OS was widely used for personal computers built on Intel 8088-80486 processors.

Currently MS DOS for management personal computers practically not used. However, it should not be considered to have completely exhausted its capabilities and lost its relevance. Low requirements for hardware resources make DOS promising for practical use. Thus, in 1997, the CaShega company began work on adapting DR DOS (analogous to MS DOS) to the embedded OS market for small high-precision devices connected to the Internet and intranet networks. These devices include cash registers, faxes, personal digital assistants, electronic notebooks etc.

Operating systems Windows is a family of operating systems including: Windows 3.1, Windows for Workgroups 3.11, Windows 9X, Windows NT, Windows 2000, Windows ME (the first two are usually called operating shells, since DOS was installed separately for them). Windows 95 is characterized by ease of installation, low levels of data protection and resistance to application failures. Windows 95 has an intuitive interface, supports plug-and-play technology, and contains built-in tools for networking.

Windows 98 is a development of Windows 95. This version is tightly integrated with the Internet Explorer Web browser and contains large number drivers for old and new devices. Users note a simplified OS installation process and lower requirements for processor power, memory and disk space compared to NT. One of the varieties of Windows is Windows SE. This line of OS is designed for use on laptop computers. Windows CE is a 32-bit object-oriented multitasking OS with built-in power saving features. Version Windows CE 3.0 (2000) is closer in its capabilities to real-time systems. The main part of this compact OS is written into the flashable ROM of laptop computers. Windows NT 5.0 or Windows 2000 is a fully 32-bit OS with priority multitasking, improved memory implementation, and was designed from the ground up with reliability, security, and management features in mind. Windows 2000 comes in four flavors: Windows 2000 Professional, Windows 2000 Server, Windows 2000 Advanced Server, and Windows 2000 DataCenter Server. These versions differ in the number of services and programs included in the delivery, and the degree of hardware support.

operating system OS/2 (Operating system/2) is a single-user multitasking OS, one-way (MS DOS -> OS/2) software compatible with MS DOS and designed to work with MP 80386 and higher (IBM PC and PS/2). OS/2 can simultaneously execute up to 16 programs (each of them in its own memory segment), but among them there is only one prepared for MS DOS.

Important features of OS/2 are the presence of a multi-window user interface; software interfaces for working with the database system; effective software interfaces for working in local computer networks. The disadvantages of OS/2 include, first of all, the relatively small volume of software applications developed to date.

The operating system is the main software that manages all the hardware and other software on the computer. The operating system, also known as the "OS", interacts with the computer's hardware and provides services that applications can use.

What does the operating system do?

The operating system is the main set of software on the device that holds everything together. Operating systems interact with device hardware. They handle everything from keyboard and mouse to Wi-Fi radio, storage and display devices. In other words, the operating system handles input and output devices. Operating systems use device drivers written by hardware developers to communicate with their devices.

Operating systems also include many software products, such as common system services, libraries, and application programming interfaces (APIs), that developers can use to write programs that run on the operating system.

The operating system sits between the applications you run and the hardware, using hardware drivers as the interface between the two. For example, when an application wants to print something, it offloads that task to the operating system. The operating system sends instructions to the printer using the printer drivers to send the correct signals. The app that prints doesn't need to care what kind of printer you have or understand how it works. The OS handles the details.

The OS also handles multitasking by allocating hardware resources among several running programs. The operating system controls which processes are running and distributes them among different CPUs if you have a computer with multiple processors or cores, allowing multiple processes to run in parallel. It also manages the system's internal memory by allocating memory between running applications.

An operating system is one large piece of software that does a lot of things. For example, the operating system also controls the files and other resources that programs can access.

Most software applications are written for operating systems, which allows the operating system to do a lot of the work. For example, when you start Minecraft, you run it on the operating system. Minecraft doesn't need to know exactly how every single hardware component works. Minecraft uses various functions operating system, and the operating system translates them into low-level hardware instructions.

Operating systems aren't just for PCs

When we say "computers" run operating systems, we don't just mean traditional desktop PCs and laptops. Your smartphone is a computer, just like tablets, smart TVs, game consoles, smart watches and Wi-Fi routers. Amazon Echo or Google Home is a computer device that runs an operating system.

Familiar desktop operating systems include Microsoft Windows, Apple MacOS, Google Chrome OS and Linux. The main operating systems for smartphones are iOS from Apple and Android from Google.

Other devices, such as a Wi-Fi router, may run "embedded operating systems." These are specialized operating systems with fewer features than a regular operating system, designed specifically for one task - for example, to work with Wi-Fi router, navigation or ATM control.

Where operating systems end and programs begin

Operating systems also include other software, including user interface, which allows people to interact with the device. This could be a desktop on a PC, a touch interface on a phone, or a voice interface on a digital assistant.

An operating system is a large piece of software made up of many different applications and processes. The line between what is an operating system and what is a program can sometimes be a little blurry. There is no exact official definition of an operating system.

For example, on Windows the application File Explorer(or Windows Explorer) is an integral part of the Windows operating system - it even handles the rendering of your desktop interface - and the application that runs on that operating system.

The center of the operating system is the kernel

At a low level, the "core" is the main computer program underlying your operating system. This separate program is one of the first things loaded when your operating system starts. It handles memory allocation, conversion software functions in the instructions for your computer's processor and processing input and output data from hardware devices. The kernel typically runs in an isolated area to prevent unauthorized use by other software on the computer. The operating system kernel is very important, but it is just one part of the operating system.

But not everything is specific here either. For example, Linux is just a kernel. However, Linux is still often referred to as an operating system. Android is also called an operating system and it is built on the Linux kernel. Linux distributions such as Ubuntu use the Linux kernel and add additional software to it. They are also called operating systems.

What is the difference between firmware and OS

Many devices simply run “firmware,” a type of low-level software that is typically programmed directly into the hardware device's memory. Firmware is just a small piece of software designed to handle only the absolute basics.

When the computer boots, it loads the UEFI firmware from motherboard. This firmware is low-level software that quickly initializes your computer's hardware. It then boots your operating system from your computer's SSD or hard drive. (This SSD or hard drive has its own built-in firmware that manages data storage on physical sectors inside the drive.)

The line between firmware and operating system can also be a little blurry. For example, Apple's operating system for iPhones and iPads, called iOS, is often called "firmware." The PlayStation 4 operating system is officially called firmware.

These are operating systems that interact with multiple hardware devices, provide services to programs, and distribute resources among applications. However, the very simple firmware that runs on a TV remote control, for example, is not usually called an operating system.

The average user is not required to understand exactly what an operating system is. It may be useful to know what operating system you are using and what software and hardware are compatible with your device.

Hello dear readers of the site. Very often you hear the phrase “operating system”, but unfortunately not everyone understands what it actually means. In today’s article, I propose to take a closer look at the question of what Windows is and what operating systems there are.

operating system starts automatically almost immediately after turning on the computer. When you turn on the computer (press the “Power” button, which is located on system unit), then it performs self-testing, namely, it checks whether all its required hardware components are in place and whether they respond to requests. Upon successful completion of this test, the computer begins loading the operating system (OS) or allows the user to select an OS if there are several installed on the computer.

Windows operating system

Roughly speaking, the operating system is the most important program in a computer, or, more precisely, a whole complex of programs. An operating system is needed on a computer primarily to organize access regular programs(Internet browser, music player, etc.) to computer resources. For example, when several programs are running simultaneously and another part is running in the background (programs running in the background are not visible, but they are running in the system), who should perform the function of a “regulator”? who organizes when the processor will allocate resources for one program, and the hard drive will write/read information for another? It is the operating system that does this.

In addition, the OS creates an interface through which a person can conveniently work with programs. That is, it is the operating system that organizes the creation of the image that we see on the screen, processes mouse movements and clicks, presses keys on the keyboard, plays sound in the speakers, etc. It is important to understand that the operating system itself does not allow you to perform familiar actions (browse web pages, work with text documents), this requires additional programs, these programs are usually called applied ones.

Immediately after installing the operating system, in the Start menu you can find applications that allow you to perform most common actions (for example, MS Internet Explorer for the Internet or WorPad for working with text). In addition, the usual functionality of the programs offered with the operating system is not enough. Usually installed on a fresh system additional applications(for example, Mozilla Firefox for the Internet, MS Office package for working with text, etc.).

The most common operating systems today are products Windows family from Microsoft. The company's share is about 90% of the desktop computer market. The remaining 10% comes from operating systems of the Linux and MacOS family.

From the above, you understand what Windows is. But now the question arises, what operating systems are there? In order to understand which operating system is installed on your computer, it is usually enough to keep an eye on the monitor screen when loading the system. Usually at this moment you can see the logo on the screen.

Below are pictures from different versions Windows.

If Windows XP is installed on your computer, you will see the following message:

Windows Vista looks like this:

One of the latest versions of Windows 7 inscription looks like this:

And here is the Windows 8 logo:

If there is no logo when loading, then this information can be viewed in the running system.

On Windows family systems, to see the properties of the operating system, you need to right-click on the My Computer icon (on the Desktop or in the Start menu) and select “Properties” from the menu that appears. The same window can be called up if you select “Control Panel” from the Start menu and double-click the “System” icon in the window that appears. Or you can use the key combination Win+Pause/Break (win is the button with Windows logo). You can read about hotkeys. In the properties window that appears, in the “System” section it will be indicated general information about the OS, including its name and version.
The Windows operating system has come a long way from graphical shell Dos (since 1985) to modern, comfortable, reliable and affordable Windows XP and Windows 7 (more about the history Windows development You can read it in one of my articles “”).

Useful information. Latest version is Windows 8. But the most optimal operating systems that have been tested by users are Windows 7, Windows XP, today many users use them. These operating systems work stably, all programs that previously had problems in Windows 7 with compatibility with other programs have now adjusted their software products program developers, releasing new versions in which this flaw is corrected. Compared to Windows XP, it has a number of advantages, in particular, it has a more reliable security system, pleasant appearance, and ergonomic design.

Many users are in no hurry to change their familiar and convenient Windows system XP on new development the same manufacturer. By and large, there is no urgent need for this. Windows XP is still supported by Microsoft, which means having this operating system on your computer, provided the latest update package is installed (called Service Pack 3 or simply SP3) and a working antivirus is quite safe and convenient.

MacOS is an operating system from Apple, it can be found on computers from this manufacturer. It began its distribution along with the appearance of the first products from Apple and developed in parallel with Windows. But you need to know that this system can also be installed on a number of other computers not from these manufacturers.

Linux today is considered the most “exotic” option for a desktop computer. This operating system is distributed free of charge (for many this is considered its main advantage over its competitors). It has several modifications (they are usually called distributions), each of which is distributed and supported by different companies.

As a regular “home” version, the most common distribution is called Ubuntu. Recently, Ubuntu has made a big step forward in bringing Linux closer to the average user, for example, a distribution like Linux XP is this confirmation, but it is distributed as paid product. However, only some enthusiasts and people who work closely with computers (for example, programmers and system administrators) still decide to switch to it or at least try it.