Windows operating system. General characteristics. III. Describe the main operating systems (purpose, modes of operation, etc.) Main characteristics of operating systems ugrinovich

The software market is widely represented by products designed for automated analysis of financial and economic activities. The financial condition of the enterprise is described using indicators and ratios, as well as in the form of graphs and charts. Automated systems provide information on the structure of the balance sheet, values \u200b\u200bof liquidity indicators, financial stability, profitability, turnover, profitability, cash flow.

The DOS operating system consists of the following parts:

1. Basic input-output system (BIOS), located in the read-only memory (read-only memory, ROM) of the computer. This part of the operating system is built into the computer. Its purpose is to perform the most simple and universal services of the operating system associated with the implementation of input / output. The basic I / O system also contains a computer function test that checks the operation of the computer's memory and devices when the computer is powered on.

An operating system is a program that is loaded when you turn on your computer. It carries out a dialogue with the user, manages the computer, its resources (RAM, disk space, etc.), launches other (application) programs for execution. The operating system provides the user and application programs with a convenient way to communicate (interface) with computer devices.

The main reason for the need for an operating system is that elementary operations for working with computer devices and managing computer resources are very low-level operations; therefore, the actions required by the user and application programs consist of several hundred or thousands of such elementary operations.

In addition, the underlying I / O system contains a program to invoke the operating system loader.

The operating system loader is a very short program found in the first sector of every DOS diskette. The function of this program is to read two more operating system modules into memory, which completes the DOS boot process.

On a hard disk (hard drive), the operating system loader consists of two parts. This is due to the fact that a hard drive can be divided into several partitions (logical drives). The first part of the bootloader is located in the first sector of the hard disk, it chooses from which partition of the hard disk to continue booting. The second part of the bootloader is located in the first sector of this section, it reads DOS modules into memory and transfers control to them.

Disk files 10.SYS and MSDOS.SYS (they may be named differently, for example, IBM.COM and IBMDOS.COM for PC DO; URBIOS.SYS and DRDOS.SYS for DR DOS, - the names change depending on the version of the operating system ). They are loaded into memory by the operating system loader and remain permanently in the computer's memory. The I0.SYS file is an addition to the basic I / O system in ROM. The MSDOS.SYS file implements the basic high-level DOS services.

The DOS shell processes commands entered by the user. The command processor is located in the disk file. COMMAND.COM on the disk from which the operating system is loaded. Some user commands (such as Type, Dir, or Sor) are executed by the shell itself. Such commands are called internal commands. To execute other (external) user commands, the command processor searches the disks for a program with the appropriate name and, if it finds it, loads it into memory and transfers control to it. When the program finishes, the command processor removes the program from memory and displays a message that it is ready to execute commands (DOS prompt).

DOS external commands are programs that come with the operating system as separate files. These programs perform maintenance actions, such as formatting floppies, checking disks, etc.

Device drivers are special programs that complement the DOS I / O system and provide service to new or non-standard uses of existing devices. For example, with the help of drivers, it is possible to work with an "electronic disk" ie. a piece of computer memory that you can work with just like a disk. Drivers are loaded into the computer memory when the operating system is booted, their names are specified in a special file CONFIG.SYS. This arrangement makes it easier to add new devices, allowing you to do this without affecting the DOS system files.

The Windows operating shell is a Microsoft add-on for the DOS operating system that provides a wide range of features and conveniences for users and programmers. The widespread distribution of Windows made 661 the de facto standard for IBM PC-compatible computers: the vast majority of users of such computers work in "" Windows, therefore, recently, almost all new programs are developed specifically for their operation in the Windows environment. "Unlike shells like Norton Commander, Windows not only provides a convenient and intuitive interface for manipulating files, disks, etc., but also provides new opportunities for programs run in the Windows environment. Of course, to use these features, programs must be designed to fit Windows. Such programs cannot run outside the Windows environment, so we will call them Windows programs or WincSows applications. However, Windows can run regular programs designed for DOS. However, such programs do not take advantage of Windows and are slower than when called directly from DOS.

Windows is an integrated program. Under the control of the Windows shell, not only special programs developed for operation in the Windows environment (Windows applications) can run, but also "ordinary" programs that run in the DOS environment, since DOS applications (DOS application programs). The Windows shell provides an efficient and convenient exchange of information between individual programs running under its control. Here we are talking primarily about Windows applications. The concept of integration is also usually associated with the ability to share computer resources by different programs. So, for example, a printer connected to a computer can be used with equal success by all programs on a competitive basis. Moreover, all the operations associated with the need for transcoding, changing drivers (for example, when switching from printing texts to displaying illustrations) is taken over by the shell.

Most users are attracted to the Windows environment not only and not so much by the comfort of the shell itself, but by the specifics of the applications implemented in this environment. The peculiarities of the implementation in the Windows environment of even familiar to users from work in DOS of application programs (applications) practically allow us to consider Windows versions of these programs as completely new products.

Working in the Windows shell and in Windows applications involves a kind of rebuilding of the "lifestyle". The "life" of the user in the Windows environment is associated with "mouse" control, data exchange between separate programs and parallel execution. Standardization of the interfaces of individual Windows applications makes it easy to move from one application to another, without starting from scratch every time (at least in terms of methods and means of management).

There are several applications in the proprietary Windows package. All of them are grouped under Accessories (accessories, tools). These are applications that are small in size and capabilities and constitute the "gentleman's set" of the user. They are far from professional specialized packages. But they perfectly illustrate the capabilities of the shell and provide some minimal service. Moreover, it is very useful to start acquaintance with serious packages with the appropriate tools of this group. So, for example, after working for some time with the text editor Write, in the future you can easily switch to using such professional word processing packages as Word for Windows, Lotus Ami Professional, WordPerfect for Windows "etc.

In the early 90s. the procedural approach still prevailed, but there are some signs of object-oriented development. At the same time, the object linking and embedding (OLE) method appeared, which allows by clicking on the image of an object to implicitly launch the application that processes it, and after finishing the processing, return to the previous application.

Closely related to OLE is the so-called "in-place" document editing method. If an object is embedded in the document that should be processed by a specific application, then when you click on this object, the required application is implicitly launched, and nothing in the working area is changed except for the toolbars. For example, if the text that is processed in the Microsoft Word editor contains a table created in the Microsoft Excel editor, then clicking on it will replace the Excel toolbars. The user can process the document with a completely different application, without even knowing about it,

Another mechanism that has simplified the work and brought the era of object-oriented approach closer is called "Drag & Drop", which literally means "drag and drop". Using this method, you click (usually left) on the image of an object, move it across the screen while holding down the button, and release the button when the pointer is in the desired location on the screen. Thus, copy, move and delete procedures became object-oriented.

The Microsoft Office suite of programs includes such as: Access, Binder, Excel, Word, Power Point, Outlook, Photo Editor. This is a standard software package that allows even a novice user to work with a computer, including both a local network and a large-scale use of Internet resources. Now it is the most widespread set of programs in Russia. There are many others, but, as a rule, when buying a computer, this particular set of programs is usually present on it. They are fully Russified and adapted for the Russian user.

The spread of computer technologies in Russia has been going on at a fast pace since 1996, but with this spread and complication, software and computer networks have a number of disadvantages. The first of these shortcomings is that, as a rule, computers of foreign production or assembly are used in Russia. This disadvantage can be attributed to the lack of specialists.

As a tool for supporting application development, MultiEdit provides the ability to customize to the type of a specific programming language. It can be used as a programming environment for compilers that lack it. When configuring to a programming language, you can set command line switches.

When setting up for a specific programming language, the most useful, which greatly facilitate the development of programs, are the following 4 mechanisms: color highlighting of syntactic constructions, automatic formatting of programs, construction of typical syntactic constructions from templates, search for paired operator brackets.

If we consider MultiEdit from the standpoint of document preparation, then it provides text formatting, generation of indexes and tables of contents. It includes spelling and sorting tools and a number of other features. The limitations of the editor include the lack of: the concept of a font, the ability to choose a typeface, insert images, support for WYSWYG mode.

The scientific document editor Chiwriter is a fairly simple and easy-to-use software system. It has a user-friendly interface. Allows you to conveniently prepare documents with complex multi-level formulas. It provides automatic pagination, allows for footers and headers.

Chiwriter has a fairly large set of fonts of various typefaces. In addition, the user has the ability to independently change the appearance of the symbols of existing fonts or create new fonts. However, the editor's fonts are bitmap and, as a result, not scalable. Cannot print high quality output with inkjet and laser printers. Another major drawback is its inconsistency with the PostScript standard, which significantly limits its use for preparing scientific papers for printing.

Using a lookup table that can contain one or two variables with an arbitrary number of values. These variable values \u200b\u200bare used when calculating the results using the same formula. The results are then displayed as a dataset.

Exel Spreadsheet Processor also supports common word processor functionality, such as macros, charting, autocorrect and spell checking, styles, templates, data auto-formatting, data exchange with other applications, advanced help system, print with parameter settings and other service opportunities.

It is advisable to use the Excel spreadsheet processor to create tables in cases where complex calculations, sorting, filtering, statistical analysis of arrays, and charting based on them are assumed.

Let's describe the main key concepts used when working with the Excel spreadsheet processor.

The workbook is the main Excel document. It is stored in a file with an arbitrary name and xls extension. When you create or open a workbook, its contents are presented in a separate window. Each workbook contains 16 worksheets by default.

Sheets are designed for creating and storing tables, charts and macros. The sheet consists of 256 columns and 16384 rows.

A cell is the structural smallest unit for placing data within a worksheet. Each cell can contain data in the form of text, numbers, formulas, or formatting options. When entering data, Excel automatically recognizes the data type and determines the list of operations that can be performed with them. By their content, cells are divided into source (influencing) and dependent. The latter contain formulas that have links to other cells in the table.

The structure and capabilities of operating systems evolve year after year. Recently, new operating systems and new versions of existing operating systems have included some structural elements that have made great changes in the nature of these systems. Modern operating systems meet the demands of constantly evolving hardware and software. They are able to control the operation of multiprocessor systems that run faster than conventional machines, high-speed network devices and a variety of storage devices, the number of which is constantly increasing. Among the applications that have influenced the design of operating systems are multimedia applications, Internet access facilities, and the client / server model.
The relentless increase in requirements for operating systems leads not only to better architecture, but also to the emergence of new ways of organizing them. A wide variety of approaches and building blocks have been tried in experimental and commercial operating systems, most of which can be grouped into the following categories.

• Microkernel architecture.
• Multithreading.
• Symmetric multiprocessing.
• Distributed operating systems.
• Object oriented design.

A distinctive feature of most operating systems today is a large monolithic kernel. The kernel of the operating system provides most of its capabilities, including scheduling, working with the file system, networking, operating device drivers, memory management, and many others. Typically, a monolithic kernel is implemented as a single process, all of whose elements use the same address space. In a microkernel architecture, the kernel is assigned only a few of the most important functions, including address spaces, interprocess communication (IPC), and basic scheduling. Other operating system services are run by processes that are sometimes referred to as servers. These processes are launched in user mode and the microkernel works with them in the same way as with other applications.

This approach separates the task of operating system development into kernel development and server development. Servers can be customized to meet the requirements of specific applications or environments.

Allocating a microkernel in the system structure simplifies the implementation of the system, ensures its flexibility, and also fits well into a distributed environment. In fact, the microkernel interacts with the local and remote servers in the same way, which simplifies the construction of distributed systems.

Multithreading is a technology in which a process running an application is split into several concurrently executing threads. Following are the main differences between thread and process.

Flow... A dispatched unit of work that includes the processor context (which includes the contents of the program counter and the top of the stack pointer) and its own stack area (for organizing subroutine calls and storing local data). Stream commands are executed sequentially; a thread can be interrupted when the processor switches to processing another thread.

Process... A collection of one or more threads and associated system resources (such as a region of memory containing code and data, open files, various devices). This concept is very close to the concept of a running program. By splitting the application into multiple threads, the programmer takes full advantage of the application's modularity and the ability to manage application-related timing events.
Multithreading turns out to be very useful for applications that perform several independent tasks that do not require sequential execution. An example of such an application is a database server that simultaneously accepts and processes multiple client requests. If multiple threads are being processed within the same process, then switching between different threads has less CPU overhead than switching between different processes. In addition, threads are useful in structuring processes that are part of the operating system kernel, described in later chapters.
Until recently, all single user personal computers and workstations contained a single general purpose virtual microprocessor. As a result of the ever-increasing demands for performance and lowering the cost of microprocessors, manufacturers have shifted to multi-processor computers.

To improve efficiency and reliability, symmetric multiprocessing (SMP) technology is used.

This term refers to the hardware architecture of a computer, as well as the operating system's behavior that matches that architectural feature. Symmetric multiprocessing can be defined as a stand-alone computer system with the following characteristics.

1. The system has multiple processors.
2. These processors, interconnected by a communication bus or some other circuitry, share the same main memory and the same I / O devices.
3. All processors can perform the same functions (hence the name symmetrical processing).

An operating system running on a symmetric multiprocessor system distributes processes or threads across all processors. Multiprocessor systems have several potential advantages over uniprocessor systems, including the following.

Performance. If a job to be performed by a computer can be organized so that parts of the job are executed in parallel, this will result in improved performance over a uniprocessor system with the same type of processor. The above statement is illustrated in Fig. 2.12. In multitasking mode, only one process can run at the same time, while the rest of the processes are forced to wait for their turn. In a multiprocessor system, multiple processes can run concurrently, each running on a separate processor.

Reliability. With symmetric multiprocessing, a failure of one of the processors will not bring the machine to a standstill, because all processors can perform the same functions. After such a failure, the system will continue to work, although its performance will decrease slightly.

Building up. By adding additional processors to the system, the user can improve its performance.

Scalability. Manufacturers can offer their products in various configurations that vary in price and performance, designed to work with different numbers of processors.
It is important to note that the benefits listed above are potential rather than guaranteed. To properly realize the potential inherent in multiprocessor computing, the operating system must provide an adequate set of tools and capabilities.

Locked
- Performed
Fig. 2.12. Multitasking and multiprocessing

You can often find a joint discussion of multithreading and multiprocessing, but the two concepts are independent. Multithreading is a useful concept for structuring application and kernel processes, even on a single processor machine. On the other hand, a multiprocessor system can have advantages over a uniprocessor system, even if the processes are not split into multiple threads, because such a system can run multiple processes at the same time. However, both of these possibilities are in good agreement with each other, and their combined use can give a noticeable effect.

A tempting feature of multiprocessor systems is that the presence of multiple processors is transparent to the user - the operating system is responsible for distributing threads between processors and for synchronizing different processes. This book discusses the scheduling and synchronization mechanisms that are used to ensure that all processes and processors are visible to the user as a single system. Another task of a higher level is to present a cluster of several separate computers as a single system. In this case, we are dealing with a set of computers, each of which has its own primary and secondary memory and its own I / O modules. A distributed operating system creates the appearance of a single space of the main and secondary memory, as well as a single file system. Although the popularity of clusters is growing steadily and more and more cluster products are appearing on the market, modern distributed operating systems are still lagging behind single- and multiprocessor systems. You will meet similar systems in the sixth part of the book.

One of the latest innovations in the design of operating systems has been the use of object-oriented technologies. Object-oriented design helps to clean up the process of adding additional modules to the main small core. At the operating system level, an object-oriented structure allows programmers to customize the operating system without compromising its integrity. In addition, this approach facilitates the development of distributed tools and complete distributed operating systems.

There are several types of operating systems: DOS, Windows, UNIX, Macintosh OS, Linux. Other modern operating systems, such as Linux, UNIX, OS / 2, have their advantages and disadvantages. Linux provides the most advanced protection than Windows and has a more sophisticated interface; UNIX is used wherever high system reliability is required. A big drawback of OS / 2 and UNIX is the rather meager choice of software tools, and here Windows outperforms other operating systems.

The most common operating system is Windows. There are several versions of Windows: Windows-3.1, Windows-95, Windows-98, Windows-2000, Windows NT. All of them are close in content. Therefore, consider OS such as DOS and Windows-95.

MS-DOS is one of the first operating systems and one of the most famous. The peak of the popularity of this operating system falls on the 90s, now this operating system is rarely used. The most popular operating systems in the world at the moment are Microsoft. Their share is about 90% among all operating systems. The most stable systems of this company are based on NT technology.

DOS operating system

The DOS operating system consists of the following parts:

1) Basic input-output system (BIOS), located in the permanent memory (read-only memory, ROM) of the computer. This part of the operating system is “embedded” in the computer. Its purpose is to perform the most simple and universal services of the operating system associated with the implementation of input / output. The basic input / output system also contains a test of the functioning of the computer, which checks the operation of the memory and devices of the computer when its power is turned on. In addition, the underlying I / O system contains a program to invoke the operating system loader.

2) The operating system loader is a very short program found in the first sector of every DOS diskette. The function of this program is to read two more operating system modules into memory, which completes the DOS boot process.

3) The DOS command processor processes commands entered by the user. The command processor is in the disk file! COMMAND.COM on the disk from which the operating system boots. Some user commands, such as Toure, Dir or Soor), the shell executes itself. Such commands are called internal commands. To execute other (external) user commands, the command processor searches the disks for a program with the corresponding name and, if it finds it, loads it into memory and transfers control to it. When the program finishes, the command processor removes the program from memory and displays a message that it is ready to execute commands (DOS prompt).

External DOS commands are programs that come with the operating system as separate files. These programs perform maintenance actions, such as formatting floppies, checking disks, etc.

Device drivers are special programs that complement the DOS I / O system and provide service to new or non-standard uses of existing devices. For example, with the help of drivers it is possible to work with a "ram disk" ie. a piece of computer memory that you can work with just like a disk. Drivers are loaded into the computer memory when the operating system is booted, their names are specified in a special file CONFIG.SYS. This arrangement makes it easier to add new devices, allowing you to do this without affecting the DOS system files.

Window-95 evolved from a graphical DOS add-on to a full-fledged operating system. At least that's what its developers said. In fact, everything was more complicated: the good old DOS was still used as the basis in Windows-95. Slightly modernized, of course, and not declared as a separate product. However, most consumers were satisfied with this option. After all, they still had the opportunity to work in the usual DOS mode without loading the Windows graphical shell, and, therefore, not to part with the familiar DOS programs.

Also, the Window-95 operating system has become 32-bit. All previous versions of DOS and Windows were 16-bit and, therefore, could not fully exploit the capabilities of even the 386 family of processors, and even more so the new Pentium processors. Of course, this advantage also had some inconveniences. Especially under Windows, users had to replace all their Windows programs with new 32-bit versions. In practice, however, the transition has been relatively easy. New versions of all popular software products were released within a year. But the old 16-bit versions could work with the new OS without any problems.

Windows XP is a multi-user, multi-tasking network OS with a graphical interface. It uses 3 variants of the file system (FAT 16, FAT 32, NTFS)
Key Features: - 32-bit architecture displacing multitasking;

Multithreading (allows you to simultaneously run several, unrelated to each other, sections of the program; - the ability to connect new devices via Plug and Play; - compatibility with earlier versions; - the presence of communication programs; - the ability to use virtual memory.

Preemptive multitasking is a type of multitasking in which the operating system can temporarily interrupt the current process without any help from it. Due to this, hung applications as a rule do not finish the operating system.

The main purpose of operating systems is to provide interaction between humans, equipment and programs. Operating systems are not required to have tools designed to perform specific application tasks - there is application software for this. However, the Windows operating system comes with a limited set of applications that can help you perform some of the simplest day-to-day tasks until you have more powerful software installed on your computer. Such programs included with Windows are called standard application programs. Due to their particular simplicity, it is customary to consider them as educational. Knowledge of techniques for working with standard applications allows you to accelerate the development of specialized software tools.
Windows XP is the first Microsoft operating system with a fully customizable interface.
The Windows operating system has a whole arsenal of simple and not only built-in programs that are not a sin to use in the absence of more professional analogues, but for novice PC users who have just started their journey in the world of high computer technologies, they will become a good platform for starting and learning. With the help of standard programs, you can draw, type text documents, communicate by e-mail, watch movies and listen to music. Examples of this can be said: 1) Notepad program. Notepad is a simple text editor that can be used as a convenient means of viewing text files. 2) Graphic editor Paint. Graphic editors are called editors designed to create and edit images (drawings) Paint - the simplest graphic editor. 3) WordPad word processor. Word processors, like text editors, are used to create, edit and view text documents. 4) calculator
44. Windows file system. Basic Windows objects (file, folder, document, shortcut, application).

In Windows OS, applications, folders, documents are considered as objects, therefore, the user is provided with the possibility of the so-called object-oriented approach.

All objects have certain properties, and certain operations can be performed on them. For example, documents have a certain volume, they can be copied, moved, renamed. The windows are sized and resizable. Folders can be opened, copied, moved, renamed. Although each of these objects has different properties, you can perform various actions with them, the technology for working with objects and the interface are universal. This allows the user to achieve consistency when working with different objects.

You can familiarize yourself with the properties of any object, and also perform operations on it that are allowed for it, by calling context menu.

Basic Windows concepts:

1.Document - any filecreated by the user. 2. Tool - a program with which the user's documents are created and edited. 3. Folder - serves to streamline the storage of documents (analogue of a directory in MS DOS). A folder, like a directory, can contain subfolders. 4. Basket - technology that allows you to throw away unnecessary documents. five. Pictogram or an icon - a conventional graphic symbol with an inscription and uniquely related with the corresponding object. 6. Label - a conditional graphic symbol with the help of which a link to an object is organized. This is the path to an object that is stored elsewhere or a special communication file. Multiple shortcuts can be organized for the same object; deleting a shortcut does not delete the object itself. 7. Desktop - hidden folder \\ Windows \\ Desktop - it cannot be absolutely clean. It is advisable to create shortcuts on the desktop for quick access to the most frequently used disks, folders and documents. Command center... There are several of them on Windows. These are special application and control programs.

Taskbar (Start button - programs, documents, settings, help, execute, stop and shutdown; buttons for all open folders and programs); - my computer (a tool that allows you to get information about the composition of the computer, disks, folders); - printers; - control Panel; - Network Neighborhood (a tool that provides quick access to network resources - disks, printers, common to all computers on the network). Menu... This is a set of all kinds of commands, from which you have to choose one. An example is the Windows main menu that appears after pressing the START button. The menu is a list of commands from which you must make a choice. The choice of the command is carried out by mouse button and click

45. Windows graphical interface, its elements.

Currently, all operating systems for personal computers provide user interaction using a graphical interface. This allows even a novice computer user to confidently work in the operating system environment (perform operations with files, run programs, and so on). The graphical interface allows for human-computer interaction in the form of a dialogue using windows, menus and controls.

GUI operations: 1. Mouse operation... To work with the graphical interface, a mouse or other coordinate input device is used, while the user must be able to perform: - left click - single pressing and releasing the main (usually left) mouse button; - right click - a single press and release of an additional (usually right) mouse button; - double click - two clicks of the main mouse button with a minimum time interval between them; - drag and drop - pressing the left or right mouse button and moving the object with the button pressed. 2. The desktop. The main part of the screen is occupied by the Desktop, on which there are icons and shortcuts (icons with small arrows in the lower left corner). Icons and shortcuts provide (double-click) quick access to drives, folders, documents, applications, and devices. 3. Taskbar... At the bottom of the screen is the Taskbar, which contains the Start button, buttons for running tasks and open folders, indicators and a clock.

4. Windows... The most important element of the Windows graphical interface is windows, because "windows" in translation means "windows". There are two main types of windows - application windows and document windows.

5. Menu. The menu is one of the main elements of the graphical interface and is a list of commands (usually thematically grouped), from which you need to make a choice (by placing the mouse pointer on the menu item and clicking). Selecting a menu item leads to the execution of a specific command.

6. Dialogue panels.Dialog boxes can include a variety of elements.

7. Tabs. Dialog boxes can include several "pages" called tabs.

8. Command buttons... Pressing the button (clicking) provides the performance of one action or another, and the inscription on the button explains its purpose. Thus, clicking on the button labeled Find allows you to start the search process.

9. Text fields. The text field is sometimes called the edit field and allows you to maintain a page, etc.

Today, a huge part of the world's population interacts with computers on an ongoing basis, someone is obliged to work, someone is looking for information on the Web, and someone just spends time in games. Everyone has their own needs, which means the computer must meet them. And if we are talking about hardware (the technical component of the computer), then everything is more or less clear: the newer, the better. But the "software" (software) part requires special attention.

Each computer is running a specific operating system, of which there are a great many, each of which is suitable for certain tasks, available equipment, and so on. Therefore, the choice of this operating system is an important factor.

There is a fairly massive list of operating systems, but in this article we will talk about three pillars that have strongly influenced the industry and occupy the bulk of all operating systems: Windows, MacOS and Linux.

Proprietary operating systems

First, it’s worth clarifying that there are proprietary OSs, those that are licensed by the manufacturer. These include Windows, which are listed below, and MacOS. Despite the fact that both systems can be downloaded onto the Web (stolen), it will be correct to purchase a license from the distribution company and activate it.

The advantage of such systems is their development, a huge amount of high-quality software and competent technical support that will help in case of problems.

"Free" operating systems

This includes almost the entire Linux family, with the exception of some developments with accounting or other professional software. These OS can be downloaded absolutely free and installed on any computer without a twinge of conscience.

Such systems are created by independent developers together with the community, therefore, in most cases the quality of programs leaves much to be desired, but such systems are much more protected and work more stable than their proprietary competitors.

Windows

Absolutely everyone who has ever dealt with a computer knows about this Microsoft product. In particular, this concerns the super-successful release of Windows 7. The list of Microsoft operating systems is already a dozen generations old. They are extremely popular all over the world and occupy almost 90% of the market. Which speaks of unprecedented leadership.

• Windows XP;
• Windows Vista;
• Windows 7;
• Windows 8;
• Windows 10;

The list deliberately starts with Windows XP, as it is the oldest version still in use today.

Chrome OS

An underdeveloped product from Google, which is limited only to web applications and the browser of the same name. This system is not competitive in comparison with Windows and Mac, but is made with an eye to the future, when web interfaces can replace the "real" software. Installed by default on all Chromebooks.

Installing multiple systems and using virtual machines

Since each platform has its pros and cons, it is often necessary to work with several at once. Computer developers are aware of this, so they offer users the ability to install two or three systems on the disk at once.

This is done simply. Only a distribution kit of the system (a disk or a flash drive with the installation material loaded on their installation) and free space on the hard disk are needed. All modern operating systems offer to allocate space during installation and create a boot mechanism that will show a list of operating systems when the computer boots. Everything is done in semi-automatic mode and can be done by any user.

Apple computers have a special utility - BootCamp, which is designed to easily and seamlessly install Windows alongside macOS.

There is another way - installing a virtual system inside a real one. For this, programs are used: VmWare and VirtualBox, capable of emulating the work of a full-fledged computer and running operating systems.

Instead of a conclusion

The list of computer operating systems is not limited to the above. There are many products from different companies, but they are all quite specific and do not deserve the attention of an ordinary user. The choice should be made between Windows, macOS and Linux, as they can cover most of the needs and are quite easy to learn.