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Computer science operating systems main characteristics. III

Operating system - it is a program that starts immediately. Among all system programs with which computer users have to deal, operating systems occupy a special place.

The operating system (OS) controls the computer, runs programs, provides data protection, performs various service functions at the request of the user and programs. Each program uses the services of the OS, and therefore can only run under the control of the OS that provides services for it. Thus, the choice of OS is very important, as it determines which programs you will be able to run on your computer. The choice of OS also affects the performance of your work, the degree of data protection, the necessary hardware, etc. However, the choice of operating system also depends on specifications(configuration) of the computer. The more modern the operating system, the more features it provides and the more visual, but also the more it makes demands on the computer ( clock frequency processor, RAM and disk memory, availability and capacity of additional cards and devices).

The main reason for the need for an OS is that elementary operations for working with computer devices and managing its resources are very low-level operations, so the actions that a user and application programs need consist of several hundred or thousands of such elementary operations.

The operating system hides these complex and unnecessary details from the user and provides him with a convenient interface for work. It performs various support activities such as copying and printing files.

The OS is loading into RAM all programs, transfers control to them at the beginning of their work, executes various activities at the request of running programs and releases the RAM occupied by programs when they complete.

Basic input/output system (BIOS, Basic Input/Output System), located in the permanent memory of the computer. This part of the OS is "embedded" in the PC.

Its purpose is to perform the simplest and most versatile OS services associated with I / O. 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 it is turned on. In addition, the basic input/output system contains the operating system boot caller.

The OS loader is a very short program found in the first sector of every OS floppy disk. The function of this program is to read two more OS modules into memory, which complete the boot process.

The OS bootloader on the hard disk consists of two parts. The first part of the bootloader is in the first sector hard drive, it selects which hard drive partition to continue booting from. The second part of the bootloader is located in the first sector of the same partition, it reads OS modules into memory and transfers control to them.

Disk files IO.SYS and MSDOS.SYS (they may be named differently, for example, IBMBIO.COM and IBMDOS.COM for PC DOS, DRBIOS.SYS and DRDOS.SYS for DR DOS - the names change depending on the OS version).

They are loaded into memory by the OS loader and remain permanent in the computer's memory. The IO.SYS file is an addition to the basic I/O system in ROM. The MSDOS.SYS file implements the basic high-level OS services.

The main tasks of the OS are as follows:

1. increase in computer throughput (due to the organization of continuous processing of the flow of tasks with automatic transition from one task to another and the efficient distribution of computer resources over several tasks);
2. Reducing the response time of the system to user requests by users of responses from a computer 4
3. simplified developer work software tools and employees of computer maintenance personnel (by providing them with a significant number of programming languages and various service programs).

Operating systems can be classified according to the following indicators:

1. number of users: single-user OS (Ms-DOS, Windows) and multi-user OS (VM, UNIX);
2. access: batch (OS 360), interactive (Windows, UNIX), real-time systems (QNX, Neutrino, RSX);
3. number of tasks to be solved: single-tasking (MS-DOS) and multi-tasking operating systems (Windows, UNIX).

The operating system is designed to perform the following main (closely related) functions:

1. data management;
2. task management (tasks, processes);
3. communication with the human operator.

In various operating systems, these functions are implemented on a different scale and with the help of different technical, software, information methods and tools.

Structurally, the OS is a set of programs that control the operation of a computer, identify application programs and data, and communicate between the machine and the operator. The OS improves the performance of the computing complex due to the flexible organization of the flow of tasks through the machine, the uniform loading of equipment, the optimal use of all computer resources, the standard organization of storage of large data arrays in the machine with a variety of ways to access them.

The system software also includes service programs that are designed to check the health of computer units, detect and localize device failures and eliminate their impact on the operation as a whole.

Systemic software The computer is designed to implement the adaptability of user programs to changes in the composition of computer resources. High performance computing system is provided by the OS through the use of modes batch processing and multiprogramming and the availability of special software tools for performing labor-intensive operations of input-output information.

Among the most famous first control programs are the complexes SAGE, SABER, MERCURE, implemented on a computer of the second generation. For IBM/360 computers, operating systems were developed that provide batch data processing technology and real-time operation, as well as the implementation of multi-machine and multi-processor systems.

The first functionally complete OS was OS/360. The development and implementation of the OS made it possible to delimit the functions of operators, administrators, programmers, users, as well as significantly (by tens and hundreds of times) increase the performance of computers and the degree of loading of technical means. OS/360/370/375 versions - MFT (fixed number of tasks multiprogramming), MVT (variable number of tasks), SVS (system with virtual memory), SVM (system of virtual machines) - successively replaced each other and largely determined modern ideas about the role of the OS in the general hierarchy of data management systems and tasks in data processing on a computer.

Early versions of OS / 360 were focused on batch processing of information - the input stream of tasks (ML, MD or punched cards) was prepared in advance and entered for processing in a continuous mode. Subsequently, extensions to OS/360/375 appeared that allowed for interactive processing of data from user terminals, the latest version (OS SVM) actually provided the user with a "virtual personal computer" with the full power of the IBM/360/375 computer installation. OS of other families.

OS programs constantly occupy the amount of memory set during the system configuration. The remaining parts of the OS are called from external memory on the MD as needed.

The OS ensures the implementation of the following processes in the computer system:

1. task processing;
2. system operation in the mode of dialogue and time slicing;
3. work in the system in real time as part of multiprocessor and multimachine complexes;
4. communication of the operator with the system;
5. logging the progress of computational work;
6. processing data received via communication channels;
7. functioning of input-output devices;
8. use of a wide range of debugging tools and program testing;
9. planning the passage of tasks in accordance with their priorities;
10. record keeping and control over the use of data, programs and computer resources.

The main components of the OS are control and processing programs. Control programs control the operation of the computer system, providing, in turn, automatic change of tasks to maintain continuous operation of the computer when switching from one program to another without operator intervention.

The control program determines the order of execution of processing programs and provides the necessary set of services for their execution. Main functions: sequential or priority execution of each work (task management); storage, search and maintenance of data, regardless of their organization and storage method (data management). computer operational computing

Task management programs read the input streams of tasks, process them depending on the priority, initiate the simultaneous execution of several tasks; call procedures; keep a system log.

Data management programs provide ways of organizing, identifying, storing, cataloging, and retrieving processed data. These programs manage I/O with various organization, combining records into blocks and dividing blocks into records, handling volume labels and datasets.

The failover management programs handle interrupts from the control system, log processor and external device failures, generate failure log entries, analyze the possibility of a task failing, and put the system into a standby state if the task cannot be completed.

System configuration. An application program in the OS can receive from the OS in the course of its operation the characteristics of a particular implementation of the system in which it operates: the name, version and edition of the OS, the type and technical characteristics of the computer. The OS usually has localization tools that allow you to configure the system for a specific national (local) data representation: representation of decimal fractions, monetary values, dates and times.

Every computer user knows about the Windows operating system. Today it is considered the most common, simple and convenient, focused on both the beginner and the "advanced" owner. In this article, we invite the reader to briefly get acquainted with all the operating systems of the Windows family, from the very first to the most modern. Let's present the basic information, the distinctive characteristics of the versions.

About MS Windows

Windows - "Windows". So the name of the popular OS is translated into Russian from English.

MS Windows is the name of a family of proprietary operating families Microsoft, which are focused on the use of a graphical interface for management. I must say that initially "Windows" was just a graphic add-on for MS-DOS.

In August 2014, Net Application undertook a massive statistical study. According to its results, it was revealed that 89% of personal computers in the world work with operating systems of the Windows family. Agree, a significant indicator.

Today Windows operates on x86, x86-64, IA-64 and ARM platforms. Previously there were versions for DEC Alpha, MIPS, PowerPC and SPARC.

OS development

The first versions of operating systems of the Windows family, as we have already said, were not full-fledged operating systems. These are settings for MS-DOS. Such a multifunctional extension added new processor modes, support for multitasking operations, standardization of interfaces hardware computer, uniform programs for users. This feature applies next versions:

A new stage of development - the Windows 9x family: 95 and 98, 2000, ME.

The current step of development falls on 2001-2016. Its beginning is considered the release of two versions of the popular "Windows XP" - corporate and "home". Then the versions of "Vista", 7, 8, 10 were presented.

Consider each variation of the OS in more detail.

Windows 1.0

We will reveal the features of the operating system of the Windows family. This version was Microsoft's graphical user interface for MS-DOS. Here the principle of the frame window manager was used. Helped dialogue with the operating system, unified the appearance of programs, optimized work with peripheral devices.

Bill Gates officially announced the development in 1983 in New York. 24 scientists worked on the creation of Windows 1.0. The interface entered retail sales two years later - in 1985. In the USA the product then cost 99 dollars, and in Germany - 399 marks.

One of the most significant disadvantages of the development: its use required the purchase of expensive components - a new model of the processor, mouse, and large memory for the computer.

Windows 2.0

This addition to the MS Windows family of operating systems was released in 1987. It was distinguished by new features and capabilities:

Using express Intel processor 286.
Possibilities for memory expansion and application interoperability using DDE.
Using hotkey combinations.
Using a multi-window environment.
Own API code.

Despite all of the above, this operating system did not become widespread, although there were developers who wrote programs for it. Its significant disadvantages: weak hardware, large software limitations.

Windows 3.0

The main characteristic of the operating system of the Windows family: this is the first product that has really received mass distribution. Its release began in 1990. It was explained by the fact that the OS was installed by manufacturers on the computers sold.

The MS-DOS file shell has been replaced by the "Program Manager" in this version. It also used its own add-on: "File Manager", which is used to navigate the disk.

You can select and external design. The interface was pseudo-3D: this was achieved with an expanded VGA color palette. This version already had a fully functional "Control Panel". It allowed you to operate with system settings and opened up a completely new opportunity - using an image as a desktop background.

The user assistance system was organized using HTML language already contains hyperlinks. The set of related software was also expanded:

Wordpad text editor.
Graphic editor Paintbrush.
Games "Solitaire-free cells", "Solitaire-kerchief", "Sapper".
Other utilities.

Several memory modes were supported: 16-bit and 32-bit. According to users, in terms of usability, the OS was on par with contemporary Apple Macintosh products.

Windows 3.1

What is the advantage of the operating system of the Microsoft Windows version 3.1 family? This is the first operating system from a corporation that has support for the Russian language, which is why it has become widespread in Russia.

Entered the market in 1992. There are no distinguishing features here - 3.1 was an improved version of the previous release. Added advanced settings working environment, improved the graphical interface, fixed bugs and improved stability.

Windows 95

The code name for this graphical operating system of the Windows family is "Chicago". It was released in August 1995 (the version for Russia was presented in November of the same year).

Mainly intended for home computers. It was hybrid: it supported 16-bit and 32-bit systems. It was here that the desktop appeared with familiar icons, taskbars and the “branded” Start menu.

Windows 98

The official release (after beta testing) of this version came in 1998. We list the main features, characteristics of the operating system of the Windows family:

Improved AGP support.
Modified drivers for USB.
Support for multi-monitor system operation.
The first Internet browser explorer.
Web TV support.

Released in 1999 updated version OS. It was distinguished by a more advanced browser, the addition of DVD support.

Windows 2000 and ME

The version was released, respectively, in 2000. She was characterized by:

Updated interface.
Service support Active Directory Directory.
File system standard NTFS 3.0.
IIS, introduced in version 5.0.

In the same 2000, a new version of the system was released - Windows ME (Millennium Edition). Let's take a quick look at what makes it different:

Improved work with multimedia tools.
Ability to record both audio and video conferences.
The emergence of tools for recovering information after system failures.
Lack of real mode from MS-DOS.

Windows XP and Vista

XP is the most popular operating system in the Windows group. It had a version for both home and corporate computers. Key additions:

Improved GUI.
Quick change of "users".
Capabilities remote control PC.
Improved system recovery capabilities.

In 2003, the server version of the OS saw the light - Windows Server 2003. According to its developers, great attention was paid to the security of the system. In 2006, a version of XP for low-power PCs called Windows Fundamentals for Legacy PCs (FLP) appeared.

In 2006 year to corporative clients Vista was introduced. Ordinary users were able to purchase its "home" version only in 2007. "Vista" was distinguished by the following:

New user interface controls.
Updated memory management subsystem, input-output.
The emergence of the "hibernation" mode.
Improved security features.

Windows 7

This operating system from Windows appeared on store shelves in 2007. Let's take a look at its distinguishing characteristics:

Support for "Unicode 5.1".
Multi-touch control capability.
The appearance of 50 new fonts in addition to the modified standard ones.
Support for folder aliases internally.
Tight integration with driver manufacturers.
Compatibility with a number of older applications whose launch was not possible on Vista.
New standard media player interface.
Support for multiple monitors, multimedia extensions, the ability to play audio files with low latency.

Windows 8

This version went on sale in 2012. According to statistics, it is in the second place in terms of prevalence in the world (after the 7th version).

The innovations here are:

Login with account Microsoft.
Two new methods for user authentication.
The appearance of the app store for the OS.
New version of the Internet browser: in desktop and touch versions.
Ability to restore and reset the system.
New "Task Manager".
The appearance of the "Family Safety" option.
New control panel, welcome screen change.
Improved search system.
Easily switch keyboard layouts.

Windows 10

The latest version of the operating system to date was released in July 2015. Here are its key differences from the previous ones:

Start Menu Modification: Presented as user-configurable tiles.
Change the size of the Start.
New features for using the app store.
The appearance of the "Notification Center".
Updated calendar, clock, battery indicator (for laptops).
Modern windows with new animation.
Updated welcome and block interfaces.

This concludes our review of Windows operating systems. Perhaps in the near future the list will be supplemented with a new version.

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 diagrams. Automated systems provides information on the structure of the balance sheet, the values of 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 simplest and most versatile operating system services associated with I/O. 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 it is turned on.

An operating system is a program that loads when you turn on your computer. It produces 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, so the actions that a user and application programs need consist of several hundred or thousands of such elementary operations.

In addition, the basic input-output system contains a program to call the boot loader of the operating system.

The operating system loader is a very short program found in the first sector of every DOS floppy disk. The function of this program is to read two more operating system modules into memory, which complete 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 HDD can be divided into several partitions (logical drives). The first part of the bootloader is located in the first sector of the hard drive, it selects which of the hard drive partitions to continue booting from. The second part of the bootloader is located in the first sector of this partition, 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, -- 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 command processor processes commands entered by the user. The command processor is in a disk file. COMMAND.COM on the disk from which the operating system is loaded. Some user commands (such as Type, Dir or Cop) are executed by the shell itself. Such commands are called internal. To execute the remaining (external) user commands, the command processor searches the disks for a program with the appropriate name, and if it finds it, it loads it into memory and transfers control to it. At the end of the program, the command processor removes the program from memory and displays a message about the readiness to execute commands (DOS prompt).

External DOS commands are programs supplied with the operating system in the form individual files. These programs perform maintenance activities, such as formatting floppy disks, checking disks, and so on.

Device drivers are special programs, which complement the DOS I/O system and provide service for new or non-standard uses of existing devices. For example, with the help of drivers, it is possible to work with an "electronic disk" i.e. a piece of computer memory that can be manipulated in the same way as a disk. Drivers are loaded into the computer's memory when the operating system boots, their names are specified in a special CONFIG.SYS file. This scheme facilitates the addition of new devices allows you to do this without affecting system files DOS.

The Windows operating shell is a Microsoft-developed add-on to the DOS operating system that provides a large number of features and conveniences for users and programmers. The wide spread of Windows has made 661 the de facto standard for IBM PC-compatible computers: the vast majority of users of such computers work in "" Windows, so recently almost all new programs have been developed specifically for their operation in the Windows environment. "Unlike shells like Norton Commander, Windows not only provides a convenient and visual interface for working with files, disks, etc., but also provides new opportunities for running in the environment Windows programs. Of course, to use these features, programs must be designed according to the requirements of Windows. Such programs cannot run outside the Windows environment, so we will refer to them as Windows programs or WincSows applications. However, Windows can also run regular programs designed for DOS. however, such programs do not take advantage of Windows and are slower than when invoked directly from DOS.

Windows is an integrated program. Under the control of the Windows shell, not only special programs designed for operation in the Windows environment (Windows applications), but also "ordinary" programs running in the DOS environment can work, because DOS applications (DOS application programs). The Windows shell provides an efficient and comfortable exchange of information between individual programs running under its control. Here we are talking primarily about Windows applications. The concept of integration is usually also associated with the possibility of sharing computer resources by various 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 operations associated with the need for recoding, changing drivers (for example, when switching from printing texts to displaying illustrations) are 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. Implementation features in the Windows environment, even familiar to users from working in DOS application programs(applications) practically makes it possible to consider the Windows versions of these programs as completely new products.

Working in the Windows shell and in Windows applications involves a kind of restructuring of the "way of life". The "life" of a user in the "Windows" environment is associated with "mouse" control, data exchange between individual 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 ways and means of control).

In original delivery Windows package there are several applications. All of them are grouped under Accessories (accessories, tools). These are application programs, small in size and capabilities, that make up 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 corresponding tools of this group. So, for example, after working for some time with text editor Write, then you can easily switch to professional word processing packages such as Word for Windows, Lotus Ami Professional, WordPerfect for Windows, etc.

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

Closely related to OLE is the so-called "in-place" method of editing documents. If an object is embedded in the document that should be processed by a specific application, then clicking on this object desired application is implicitly launched, and nothing changes in the workspace, except for the toolbars. For example, if in the text that is being processed in the editor Microsoft Word, there is a table created in the editor Microsoft Excel, clicking it will replace the Excel toolbars. The user can process the document with a completely different application, without even knowing it,

Another mechanism that has simplified the work and hastened the era of object-oriented approach is called "Drag & Drop", which literally means "drag-and-drop". With this method, you click (usually the left mouse button) on the image of the object, move it around the screen while the button is pressed, and release the button when the pointer is in right place screen. Thus, the procedures for copying, moving, and deleting became object-oriented.

To the complex Microsoft programs Office 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 local network and large-scale use of Internet resources. Now this is the most common 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 completely Russified and adapted to the Russian user.

The spread of computer technologies in Russia has been going at a fast pace since 1996, but with such a spread and complexity, software and computer networks have a number of drawbacks. The first of these shortcomings is that, as a rule, foreign-made or assembled computers are used in Russia. This shortcoming can be attributed to the lack of specialists.

As a tool to support the development of application programs, MultiEdit provides the ability to customize the type of a particular programming language. It can be used as a programming environment for those compilers that do not have it. When setting up a programming language, you can specify command line switches.

When tuning to a specific programming language, the following 4 mechanisms are the most useful, greatly facilitating the development of programs: color highlighting of syntactic constructions, automatic formatting of programs, building typical syntactic constructions from templates, and searching for paired operator brackets.

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

The editor of scientific documents Chiwriter is quite 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.

The Chiwriter editor has a fairly large set of fonts of various types. 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 bitmapped and, as a result, not scalable. Unable to receive when printing high quality output document when using inkjet and laser printers. Another major disadvantage is its non-compliance with the PostScript standard, which significantly limits its use for preparing scientific papers for publication.

Use of a lookup table, which can contain one or two variables with an arbitrary number of their values. These variable values are used when calculating the results of the same formula. The results are then displayed as an array of data.

The Excel spreadsheet also supports common functionality word processors, such as the use of macros, diagramming, autocorrect and spell checking, the use of styles, templates, auto-formatting data, exchanging data with other applications, the presence of a developed help system, custom printing and other service options.

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

Let us describe the main key concepts used when working with spreadsheet Excel.

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 to create and store 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, numeric values, formulas, or formatting options. When entering data, Excel automatically recognizes the type of data and determines the list of operations that can be performed with them. According to their contents, the cells are divided into initial (influencing) and dependent. The latter contain formulas that have links to other table cells.

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ROSZHELDOR

Federal State Budgetary Educational Institution

higher professional education

Rostov State Transport University

(FGBOU VPO RGUPS)

Liskinsky College of Railway Transport named after I.V. Kovaleva

(LTZhT - branch of RGUPS)

essay

by discipline

INFORMATICS

Operating systems

Completed by: student of group DK-22

option 18 Oleinikova Victoria

2014

operating system operating program

Introduction

1.3 Overview of file systems

Conclusion

Introduction

Among all the system programs that computer users have to deal with, operating systems occupy a special place.

An operating system is a program that starts right away. Among all the system programs that computer users have to deal with, operating systems occupy a special place.

The operating system (OS) controls the computer, runs programs, provides data protection, performs various service functions at the request of the user and programs. Each program uses the services of the OS, and therefore can only run under the control of the OS that provides services for it. Thus, the choice of OS is very important, as it determines which programs you will be able to run on your computer. The choice of OS also affects the performance of your work, the degree of data protection, the necessary hardware, etc. However, the choice of operating system also depends on the technical characteristics (configuration) of the computer. The more modern the operating system, the more features it provides and the more visual, but also the more it imposes on the computer (processor clock speed, RAM and disk memory, the presence and capacity of additional cards and devices).

The OS loads all programs into RAM, transfers control to them at the beginning of their work, performs various actions at the request of executing programs, and frees the RAM occupied by programs when they complete.

1. The concept of the operating system

The operating system is a complex of system and service software. On the one hand, it relies on the basic computer software included in its BIOS system(basic input-output system), on the other hand, it is itself a support for higher-level software - application and most service applications. Operating system applications are called programs designed to work under the control of this system.

The operating system has several main functions:

1. GUI is a convenient shell that the user works with.

2. Multitasking - includes the ability to simultaneously or sequentially work with several applications at once, exchange data between applications, as well as the ability to share software, hardware, network and other computing system resources by several applications.

3. The kernel (command interpreter) is a "translator" from the program language to the language of machine codes.

4. Drivers are specialized programs for managing various devices that are part of a computer.

5. File system - designed to store data on disks and provide access to them. Data about where a particular file is recorded on the disk is stored in the system area of the disk in special file allocation tables (FAT tables).

6. Bit depth - on this moment there are: 16-bit operating systems (Dos, Windows 3.1, Windows 3.11), 32-bit operating systems (Windows98, Windows 2000, WindowsMe), 64-bit operating systems (Windows XP, Windows Vista).

In addition to the main (basic) functions, operating systems can provide various additional functions. The specific choice of operating system is determined by the set of provided functions and specific requirements for the workplace. Other features of operating systems may include the following:

· Possibility to support functioning of a local computer network without special software;

· Providing access to basic Internet services by means integrated into the operating system;

· Possibility to create system means Internet server, its maintenance and management, including remote through a remote connection;

· Availability of means of protecting data from unauthorized access, viewing and modification;

· Ability to design the working environment of the operating system, including the means related to multimedia;

Possibility to ensure comfortable alternate work of different users on one personal computer while maintaining the personal settings of the working environment of each of them;

· Possibility of automatic execution of computer and operating system maintenance operations according to a given schedule or under the control of a remote server;

· Ability to work with a computer for persons with physical disabilities associated with the organs of vision, hearing and others.

Figure 1 Integrated tool in Windows operating systems for Internet access

1.1 Purpose and classification of operating systems

Purpose OC:

Organization of the computing process in a computing system;

Rational distribution of computing resources between individual tasks to be solved;

Providing users with numerous service tools that facilitate the process of programming and debugging tasks.

The operating system plays the role of a kind of interface (Interface - a set of hardware and software necessary to connect peripheral devices to a personal electronic computer (PC)) between the user and the aircraft, i.e. The OS provides the user with a virtual aircraft. This means that the OS largely forms the user's idea of the capabilities of the aircraft, the convenience of working with it, and its throughput. Different OS on the same technical means can provide the user with various options for organizing a computing process or automated data processing. In CS software, the operating system occupies a central position, since it plans and controls the entire computing process. Any of the software components must work under OS control.

This operating system must:

Be universally recognized and used as a standard system on many computers;

Work with all computer devices, including those released a long time ago;

Ensure the launch of the most different programs written by different people and at different times;

Provide facilities for checking, configuring, maintaining a computer system.

Modern operating systems are multitasking, that is, the user can run several applications at the same time, observing the result of each of them. This is possible due to the design of the OS and the functionality of modern processors - it is not for nothing that operating systems are written for the processor, and not vice versa. Modern processor is not a single-core, but a dual-core and even a quad-core solution, which increases its performance many times over. This is used by the operating system, optimally distributing processor resources between all running processes.

The main characteristics of the operating system are the stability of its operation and resistance to various threats - external (viruses) and internal (hardware failures and conflicts).

OS classification:

Depending on the processor control algorithm, operating systems are divided into:

Single-tasking and multi-tasking

Single and Multiplayer

Uniprocessor and multiprocessor systems

Local and network.

Operating systems are divided into two classes according to the number of simultaneously executing tasks:

Single-tasking (MS DOS)

Multitasking (OS/2, Unix, Windows)

Single-tasking systems use controls peripherals, file management tools, means of communication with users. Multitasking operating systems use all the features that are typical for single-tasking, and, in addition, manage the sharing of shared resources: processor, RAM, files, and external devices.

Depending on the areas of use, multitasking operating systems are divided into three types:

Batch Processing Systems (OS EC)

Time-sharing systems (Unix, Linux, Windows)

Real Time Systems (RT11)

Figure 2 Unix Desktop Screenshot

1.2 The composition of the operating system and the purpose of the components

The most important advantage of most operating systems is modularity. This property allows you to combine certain logically related groups of functions in each module. If it becomes necessary to replace or expand such a group of functions, this can be done by replacing or modifying only one module, rather than the entire system. Most OS consists of the following main modules: basic input-output system (BIOS - BasicInputOutputSystem); operating system loader (BootRecord); OS kernel; device drivers; command processor; external commands (files). The Basic Input/Output System (BIOS) is a set of firmware that implements basic low-level (elementary) I/O operations. They are stored in the computer's ROM and are written there during the manufacture of the motherboard.

This system is, in fact, "embedded" in the computer and is both its hardware and part of the operating system. The first function of the BIOS is to automatically test the main components of the computer when it is turned on. If an error is detected, an appropriate message is displayed on the screen and / or sound signal. Next, the BIOS calls the block bootstrap operating system located on the disk (this operation is performed immediately after testing is completed). Having loaded this block into RAM, the BIOS transfers control to it, and it, in turn, loads other OS modules. Another important BIOS feature is interrupt service. When certain events occur (pressing a key on the keyboard, clicking the mouse, an error in the program, etc.), one of the standard BIOS routines is called to handle the situation that has arisen. The operating system loader is a short program that resides in the first sector of any boot disk (floppy or operating system disk). The function of this program is to read into the memory of the main disk files OS and the transfer of further control of the computer. The OS kernel implements basic services, is loaded into RAM and stays there all the time.

1.3 Overview of file systems

File system FAT

FAT is the simplest file system supported by Windows NT. The basis of the FAT file system is the file allocation table, which is placed at the very beginning of the volume. Two copies of this table are kept on disk in case of corruption. In addition, the file allocation table and the root directory must be stored in a specific location on disk (in order to correctly determine the location of the download files).

A disk formatted in the FAT file system is divided into clusters, the size of which depends on the size of the volume. Simultaneously with the creation of the file, an entry is created in the directory and the number of the first cluster containing the data is set. Such an entry in the file allocation table signals that this is the last cluster of the file, or points to the next cluster.

Updating the file allocation table is very important and time consuming. If the file allocation table is not updated regularly, data loss may result. The duration of the operation is explained by the need to move the reading heads to the logical zero track of the disk with each update of the FAT table.

The FAT directory has no defined structure and files are written to the first found free space on disk. In addition, the FAT file system only supports four file attributes: System, Hidden, Read-Only, and Archive.

File system HPFS

The HPFS file system was first used for the OS/2 1.2 operating system to provide access to the large disks that were on the market at the time. In addition, there is a need to expand existing system names, organizational and security improvements to meet the growing needs of the network server market. The HPFS file system supports the FAT directory structure and adds sorting of files by name. The file name can contain up to 254 double-byte characters. The file consists of "data" and special attributes, which creates additional features to support other types of filenames and improve security. In addition, the smallest block for data storage is now equal to the size of the physical sector (512 bytes), which helps to reduce wasted disk space.

Entries in the directory of the HPFS file system contain more information than in FAT. Along with file attributes, information about creation and modification, as well as the date and time of access, is stored here. The entries in the HPFS directory do not point to the first cluster of the file, but to the FNODE. FNODE can contain file data, pointers to file data, or other structures pointing to file data.

HPFS tries to place file data in contiguous sectors whenever possible. This leads to an increase in the speed of sequential processing of the file.

HPFS divides the disk into blocks of 8 MB each and always tries to write the file within the same block. For each block, 2 KB is reserved for the allocation table, which contains information about the written and free sectors within the block. Blocking leads to better performance, since the disk head to determine where to save the file must return not to the logical beginning of the disk (usually this is cylinder zero), but to the allocation table of the nearest block.

File system NTFS

From the user's point of view, the NTFS file system organizes files into directories and sorts them in the same way as HPFS. However, unlike FAT and HPFS, there are no special objects on the disk and there is no dependence on the features of the installed hardware (for example, a 512-byte sector). In addition, there are no special data stores on the disk (FAT tables and HPFS superblocks).

The purpose of the file NTFS systems is the following.

Delivering the reliability that is essential for high performance systems and file servers.

Providing the platform with additional functionality.

Support for POSIX requirements.

Elimination of restrictions specific to FAT and HPFS file systems.

Figure 3 Structure of the FAT file system

2. Characteristics of modern operating systems

Year after year, the structure and capabilities of operating systems evolve. Recently, new operating systems and new versions of already existing operating systems have included some structural elements that have made great changes in the nature of these systems. Modern operating systems meet the requirements of constantly evolving hardware and software. They are able to manage faster multiprocessor systems, faster networking devices, and an ever-increasing variety of storage devices. Of the applications that have influenced the design of operating systems, multimedia applications, Internet access tools, and the client / server model should be noted.

The steady growth of requirements for operating systems leads not only to improvements in their 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 operating system kernel provides most of its capabilities, including scheduling, file system manipulation, network functions, operation of various device drivers, memory management and many others. Typically, a monolithic kernel is implemented as a single process, all elements of which use the same address space. In the microkernel architecture, only a few of the most important functions, which include working with address spaces, providing interaction between processes (interprocess communication - IPC), and basic planning. Other operating system services are provided by processes sometimes referred to as servers. These processes run in user mode and the microkernel treats them just like other applications.

This approach allows you to divide the task of operating system development into kernel development and server development. Servers can be customized for specific application or environment requirements.

Allocation of the microkernel in the structure of the system simplifies the implementation of the system, ensures its flexibility, and also fits well into a distributed environment.

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

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

Process: A collection of one or more threads, and the system resources associated with those threads (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 gets all the benefits of the application's modularity and the ability to manage application-related temporal events.

Multithreading is 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 accepts and processes multiple client requests at the same time. If multiple threads are being processed within the same process, switching between different threads has less CPU overhead than switching between different processes. In addition, threads are useful in structuring the processes that are part of the operating system kernel, as described in later chapters.

Until recently, all single-user personal computers and workstations contained a single virtual microprocessor. general purpose. As a result of ever-increasing performance requirements and decreasing costs of microprocessors, manufacturers have shifted to producing computers with multiple processors.

Symmetric multiprocessing (SMP) technology is used to improve efficiency and reliability.

This term refers to the hardware architecture of a computer, as well as the way the operating system behaves according to that architectural feature. Symmetric multiprocessing can be defined as a standalone computer system with the following characteristics.

The system has multiple processors.

These processors, connected to each other by a communication bus or some other circuitry, share the same main memory and the same I/O devices.

All processors can perform the same functions (hence the name symmetrical processing).

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

Performance. If a job that a computer needs to run can be arranged so that parts of the job run in parallel, this will result in better performance than a single processor system with the same type of processor. The position formulated above is illustrated in fig. 2.12. In multitasking mode, only one process can be running 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 simultaneously, each running on a separate processor.

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

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

Scalability. Manufacturers can offer their products in a variety of price and performance configurations 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 contained in multiprocessor computing systems, the operating system must provide an adequate set of tools and capabilities.

Figure 4 Multitasking and multiprocessing

It is common to see multithreading and multiprocessing discussed together, 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 may have advantages over a single processor system even if the processes are not split into multiple threads, because it is possible to run multiple processes at the same time on such a system. However, these two possibilities are in good agreement with each other, and their sharing can have a noticeable effect.

A tempting feature of multiprocessor systems is that the presence of several 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 make all processes and processors visible to the user as a single system. Another task more high level-- representation in the form of a single cluster system of several individual computers. In this case, we are dealing with a set of computers, each with its own primary and secondary memory and its own I/O modules. A distributed operating system creates the appearance of a single space of primary and secondary memory, as well as a single file system. Although the popularity of clusters is steadily growing and more and more clustered products appear on the market, modern distributed operating systems still lag behind single- and multi-processor systems in development. You will get acquainted with such 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 kernel. At the operating system level, an object-oriented structure allows programmers to customize the operating system without violating its integrity. In addition, this approach facilitates the development of distributed tools and full-fledged distributed operating systems.

Conclusion

Windows is the most common operating system, and for most users, it is the most suitable due to its simplicity, good interface, acceptable performance, and a huge number of applications for it.

I have had the opportunity to work with Microsoft operating systems from Windows 2000 to Windows versions 8, in my opinion, the most successful OS is Windows 7, which has better protection than Windowsxp, a more thoughtful interface and many other little things that make this OS more attractive. Of course, the question arises, what about Windows 8, yes it is a newer OS, but its interface is more adapted for mobile devices with a touch screen, which is why it is not so popular yet, but as I heard, Microsof released an update for Windows 8 , Windows 8.1, in which we decided to return to the desktop familiar to users.

List of sources used

1. Lecciopedia-library of lecture material. [Electronic resource] Access mode: http://lektsiopedia.org.

2. OS Journal [Electronic]. Access mode: http://www.ossite.ru/.

3. OSys.ru - operating systems [Electronic resource]. Access mode: http://osys.ru/.

4. Computer science. [Electronic resource]: textbook L.Z. Shautsukova. Access mode: http://book.kbsu.ru/.

5. Mikheeva E.V. Titova O.I. Informatics: Textbook for students of institutions environments. Prof. education. M.: Academy, 2010.

6. Informatics and information and communication technologies at school [Electronic resource]: textbook / comp. Popova O.V. Access mode: http://www.klyaksa.net/htm/kopilka/uchp/p6.htm.

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Proprietary operating systems

To begin with, it is worth clarifying that there are proprietary OSes, those that are distributed under the manufacturer's license. These include Windows, which are listed below, and MacOS. Even though both systems can be downloaded on the Web (stealed), the right thing to do is 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

These include almost the entire Linux family, with the exception of some developments with accounting or other professional software. These operating systems can be downloaded absolutely free of charge 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 secure 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 applies to the super-successful release of Windows 7. The list of Microsoft operating systems has a dozen generations. They are extremely popular all over the world and occupy almost 90% of the market. Which speaks of unparalleled leadership.

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

The list intentionally starts with Windows XP, as that 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 with Windows and Mac, but is made with an eye to the future, when web interfaces can replace "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 know this, so they offer users the opportunity to install two or three systems on a disk at once.

This is done simply. All you need is a system distribution kit (a disk or flash drive with installation material loaded on them) and free space on your hard drive. 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 a semi-automatic mode and is within the power of any user.

On the Apple computers there is a special utility - BootCamp, which is designed for a simple and seamless installation Windows nearby with macOS.

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

Instead of a conclusion

The list of operating systems for the computer is not limited to the above. There are many products from different companies, but all of them are 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.