Operating system concept. Operating system families

Windows OS is a DOS add-on developed by Microsoft that provides a wide range of features and conveniences for users and programmers. Unlike shells like Norton Commander, Windows not only provides a convenient and intuitive interface for operating with files and disks, but also provides new opportunities for programs launched in the Windows environment. Of course, to use these features, programs must be designed according to Windows requirements.

MS Windows is an integrated environment that provides efficient exchange of text, graphics, sound and video information between individual programs. The basic functionality of MS Windows covers everything that is in MS DOS, Windows 3.11.

Integrated operating system - an operating system, the kernel of which, loaded at the moment of turning on the computer, activates the graphical user interface and ensures full compatibility with the MS DOS operating system.

Benefits of Windows:

1. Convenient device support. The main difference between DOS and Windows programs is that a DOS program can work with computer hardware (monitor, keyboard, printer) directly, bypassing DOS, while a Windows program must access external devices only through Windows. Therefore, after installation in Windows driver supporting this device, all Windows programs can work with this device. This eliminates the painful DOS problem of ensuring compatibility of programs with specific external devices. Programs (drivers) to support the most common devices are included in Windows, and for other devices, they are supplied with these devices or controllers.

2. Unified user interface. Windows provides programmers with all the tools they need to create a user interface, so programmers use them rather than inventing their own. As a result, the user interface of a Windows program is largely unified, and users do not need to learn new principles for organizing interaction with this program for each program.

3. Scalable font support. Applications such as document editing, publishing, advertising, spreadsheet or presentation creation require a wide variety of fonts — text, header, decorative — and the characters in these fonts may be required in a wide variety of sizes. Therefore, Windows 3.1 has built-in support for scalable True Type fonts. Scalable fonts contain character outline descriptions that allow you to build characters of any size you want.

4. Multimedia support. When connected to appropriate devices, Windows can accept sounds from a microphone, CD or MIDI synthesizer, images from a digital video camera or CD, and output sounds and motion pictures. Windows is a highly efficient multimedia platform. This operating environment allows multimedia applications to perform at their best. Windows-based multimedia personal computers provide excellent picture and sound quality. Windows provides support for multimedia devices such as video discs and VCRs. This support simplifies the process of preparing the system for time-lapse shooting - based on high-quality video.

5. Multitasking... Windows provides the ability to run multiple programs at the same time and switch from one program to another.

6. Data exchange facilities. To organize the exchange of data between various programs, Windows offers the following methods:

Data exchange buffer (one program can put data into this buffer, while another can use data from the buffer);

Dynamic data exchange (one program can use data linked by another program, and a copy of the data in the using program retains the link to the original);

The mechanism of communication and implementation (a program using embedded data can edit this data, for which the program with which this data was created is automatically launched).

7. Compatible with DOS programs. Working in a Windows environment does not force you to abandon the use of DOS programs. Moreover, there is usually no need to exit Windows to run DOS programs.

8. Use of Plug and Play technology. Windows uses Plug and Play technology extensively to provide new ways to integrate software and hardware. It is focused on supporting any type of device, including monitors, video cards, printers, sound cards, modems, CD-ROM drives, various hard disk controllers, etc.

Plug and Play technology simplifies computer use through the following service features:

- assistance in recognizing devices for their installation and configuration;

- notification of software products and applications and dynamic changes in the state of the system;

- Tight integration of device drivers, system components and user interface, making it easy to configure and manage the system.

In Windows, a user simply plugs it in to connect a new Plug and Play device. Redistribution and tuning of system resources then occurs automatically.

Windows Plug and Play also allows you to work with non-Plug and Play devices, making it easy to configure and manage your hardware.

Disadvantages of Windows:

1. The benefits described above come from a significant increase in the load on the computer's hardware. Often programs with approximately the same capabilities for DOS and for Windows differ in the requirements for computer resources dozens of times.

2. Windows programs do not perform well in those applications where time is a critical resource.

3. The most significant disadvantage of Windows is its very low reliability. Incorrect operation of any Windows program can cause the entire Windows to freeze. In addition, the limited nature of these Windows resources makes it impossible for Windows to run more than three or four serious programs at the same time, no matter how much RAM and disk space is in the computer.

4. Windows does not provide almost any protection against damage to the OS. With active use of Windows, the system often loses its functionality, and you have to reinstall it or repair damage, working in DOS mode.

In operating systems that have an interface command line, navigation the file system is carried out by entering commands for switching from disk to disk or from directory to directory. Due to the extreme inconvenience of such navigation (it is necessary to remember the commands, to accurately type them on the keyboard character by character), special utility programs called file wrappers.

Shell programs provide the user with a qualitatively new interface and free him from detailed knowledge of OS operations and commands. The functions of most shells, for example, the MS DOS family, provide faster and more convenient work with the file system. Like the OS, there are non-graphical and graphical file shells. The most famous non-graphical file shells for MS DOS are the file manager Norton Commander, Dos Navigator, Volkov Commander. The role of the graphical file shell for MS DOS was once performed by Windows programs 1.0 and Windows 2.0, which gradually evolved to the concept of an operating environment (in versions of Windows 3.x) and then to a stand-alone operating system (Windows 95). OS Windows families, although they have a graphical interface, nevertheless widely use shell programs, in particular, Far Manager, Windows Commander, Total Commander shells.

An operating system (OS) is a set of software tools that manage computer resources (random access memory, disk space, etc.), launch application programs and their interaction with external devices and other programs, as well as provide a dialogue between the user and the computer.

File system

Concept and classification of operating systems

The work of the PC is carried out according to the program. The main complex of programs, without which a computer cannot work, is the operating system (OS).

Currently, the world uses a large number of operating systems that can classified into groups according to the following criteria:

1. The number of concurrent users: single-user, multi-user.

2. The number of processes simultaneously executed under the control of the system: single-tasking, multitasking.

3. The number of supported processors: uniprocessor, multiprocessor.

4. Code bits: 8-bit, 16-bit, 32-bit, 64-bit.

5. Type of interface: command (text) and object-oriented (graphical).

6. Type of user access to the computer: batch processing, time sharing, real time.

7. Type of resource use: network, local.

According to the first sign of the classification multi-user operating systems, in contrast to single-user ones, support the simultaneous operation of several users on a computer at different terminals.

Second sign assumes the division of the OS into multitasking and single-tasking. The concept of multitasking means support for the parallel execution of several programs existing within one computing system at the same time.

Single-tasking operating systems support the mode of executing only one program at a time.

According to the third sign multiprocessor operating systems, in contrast to uniprocessor ones, support the mode of allocating resources of several processors for solving a particular problem.

The fourth sign subdivides operating systems into 8-, 16-, 32-, and 64-bit. This assumes that the bitness of the operating system cannot exceed the bitness of the processor.

According to the fifth sign By the type of user interface, OS are divided into object-oriented (usually with a graphical interface) and command (with a text-based interface).

According to the sixth feature, OS are subdivided into systems:

Batch processing, in which from the programs to be executed, a package (set) of tasks is formed, entered into the computer and executed in order of priority, possibly taking into account priority;

Time sharing (TSR), providing a simultaneous dialog (interactive) mode of access to a computer for several users on different terminals, to which the machine resources are allocated in turn, which is coordinated by the operating system in accordance with a given service discipline; real time, providing a certain guaranteed response time of the machine to the user's request to control any events, processes or objects external to the computer.

According to the seventh sign OS classifications are divided into network and local. Network operating systems are designed to manage the resources of computers connected to a network for the purpose of sharing data, and provide powerful means of differentiating access to data in terms of ensuring their integrity and safety, as well as many service capabilities for using network resources. In most cases, network operating systems are installed on one or more sufficiently powerful server computers dedicated solely to serving the network and shared resources. All other operating systems will be considered local and can be used on any personal computer, as well as on a separate computer connected to the network as a workstation or client.

Consider, in accordance with this classification, the most popular families of operating systems for personal computers.

1) Operating systems of the DOS family

The first representative of this family - the system MS DOS (Microsoft Disc Operating System - Microsoft disk operating system) was released in 1981 in connection with the appearance of the IBM PC. Operating systems of the DOS family are single-tasking and have the following characteristics and features:

The interface with the computer is carried out using commands entered by the user;

Modularity of the structure, simplifies the transfer of the system to other types of computers;

Small amount available random access memory(640KB).

A significant drawback of operating systems of the DOS family is the lack of protection against unauthorized access to PC and OS resources. Currently, MS DOS 6.22 is widely used.

2) Operating systems of the OS / 2 family

The operating system OS / 2 (Operating System / 2) was developed by IBM in 1987 in connection with the creation of a new family of personal computers.

It is a 32-bit graphical multitasking operating system for IBM PC - compatible computers, allows you to organize the parallel operation of several application programs, while protecting one program from another and the operating system from programs running in it. To write programs for OS / 2, you can use ready-made software modules that are contained in the so-called application programming interface - API (Application Programming Interface).

The operating system OS / 2 has a convenient graphical user interface and is compatible with the DOS file system, which makes it possible to use data in both DOS and OS / 2 without any transformations.

There are several modifications of OS / 2:

OS / 2 Warp 3.0 - improved memory usage and improved graphical interface;

OS / 2 Warp Connect - improved networking support;

OS / 2 Warp Server - designed to work as a server OS.

The main disadvantage of OS / 2 is the small number of applications for it, which makes this system less popular than MS DOS and Windows operating systems.

3) Operating systems of the UNIX family

UNIX-family operating systems are 32-bit multitasking multi-user operating systems. The strength of UNIX is that the same system is used in different computers - from supercomputers to personal computers, which makes it possible to transfer the system from one machine architecture to another with minimal costs.

UNIX combines: access to distributed databases, local area networks, remote remote communication and the ability to access global networks using a conventional modem. The UNIX mail service is one of its most important components. There are a large number of UNIX applications nowadays. Most of the popular DOS and Windows applications can be used on UNIX.

There are several UNIX operating systems. Different versions of this family have their own names, but in general terms they repeat the features of the base UNIX OS. The UNIX OS file system protects files from unauthorized access at the user and user group levels. Currently, from the network operating systems of the UNIX family, the OS for enterprise networks is widely adopted UnixWare 2.0 - a 32-bit multi-user multitasking operating system that supports real-time applications.

4) Operating systems of the Windows family

Operating systems of the Windows family are developed by Microsoft. They are multitasking operating systems that provide a user-friendly graphical interface. The main representatives of this family are Windows 95, Windows 98 and Windows NT. Windows 95 is developed on the basis of MS DOS OS and Windows 3.x operating shells.

Windows 95 is a partially 32-bit and partially 16-bit operating system.

Operating room Windows system NT is one of the most common 32-bit network operating systems. Windows NT comes in two flavors: Windows NT Server and Windows NT Workstation. Windows NT Server is primarily designed to manage network resources. The system provides high mobility and safety without sacrificing performance. Windows NT Server contains tools for organizing a quick search for information and viewing resources of global networks, provides the ability to use any communication channels (including regular telephone lines), supports up to 256 simultaneous connections to one server, and several servers can be used to organize a public network service.

Windows NT Workstation is a version of Windows NT designed to run on local computers and workstations. It is a fully 32-bit operating system, the most secure and reliable.

All Windows NT applications run in multitasking mode. However, not all MS DOS applications and 16-bit Windows programs work under Windows NT.

Windows NT Workstation is advisable to use when you need reliable protection of confidential data or programs, as well as when performing engineering, scientific, statistical and other work when high performance is important when analyzing large amounts of data.

5) Family of real-time operating systems

The term real time in its broadest sense can be applied to an activity or information processing system in cases where it is required that the system has a guaranteed response time, that is, the response delay does not exceed a certain time.

Real-time operating system (RT OS) is an operating system that guarantees a certain response time of the system. Typically, this time ranges from a few microseconds to a few tenths of a second.

Among the most famous RT operating systems for the IBM PC are used: RTMX, AMX, OS-9000, FLEX OS, QNIX, etc.

The operating system platforms Windows NT and Windows 2000 are operating systems for use on a wide variety of computers.

The Windows NT platform includes the following operating systems:

Windows NT Workstation

Windows NT for Workgroups

Windows NT Server.

The Windows 2000 platform includes the following operating systems:

Windows 2000 Professional

Windows 2000 Server

Windows 2000 Advansed Server

Windows 2000 Datacenter Server.

	Windows Professional	Windows Server	Windows Advanced Server	Windows Datacenter Server
Application area	Desktop computers, laptop computers	File server, print server, local network, network support	Business applications, e-commerce	Large Mission Critical Applications: OLTP, Data Warehousing, ASP and ISP
Number of processors supported by the system

Windows NT Workstation and Windows 2000 Professional are client operating systems. The rest of the operating systems on these platforms are server operating systems. This overview covers only client operating systems.

The operating systems Windows 95, Windows NT, Windows 98, Windows 2000 and Windows XP are 32-bit in architecture. Windows 95, Windows 98 are single-user, uniprocessor systems. Windows NT, Windows 2000 and Windows XP are multi-user operating systems that support more than one processor.

All Windows operating systems are graphical multi-tasking systems.

WindowsNT is a 32-bit operating system that supports a fairly high degree of security. This means that it is very difficult to mess up data or files, programs do not interfere with each other's work, because each 32-bit application operates in its own Virtual Memory space (4 Gb). Security is also ensured by the fact that each user can have their own name and password to enter the system. In addition, security is provided at the level of the NTFS file system (for each file, you can specify the access rights to this file).

Windows NT supports the FAT file structure and the new technology file system (NTFS).

Windows NT supports both RISC and CISC processor architectures.

Unlike earlier versions of Windows (such as Windows for Workgroups and Windows 95), NT is a complete operating system, not an add-on to the DOS operating system.

Microsoft Windows 98 is an updated Windows 95 operating system that enhances the functionality of your computer. The advantages of this OS :

Windows 98's Web-based user interface makes search easier by unifying the presentation of information across your computer, local area network, and the Web. (See chapters on the Internet).

Faster application startup times, new disk cleaners and more efficient disk performance.

Supports next-generation hardware such as USB and DVDs, and expands your workspace across multiple monitors with the ability to connect multiple monitors and multiple graphics adapters to a single computer.

Improved version of the file allocation table file system(FAT32) allows you to increase the amount of free space on large hard drives by using it more efficiently. Converting the drive to FAT32 is done by a GUI program.

OS appeared in 2000 Windows Millennium, which became the development of the direction of OS Windows 95/98. Almost at the same time, the OS appeared Windows 2000, which was based on NT technology, while retaining all the useful features of Windows 98.

Windows 2000 was planned as an operating system to support the entire spectrum of computing technology - from laptops and desktops to clustered systems on high-end servers.

Although home users were encouraged to migrate to Windows Me, and corporate users to Windows 2000, some users were faced with a choice between the more reliable and productive Windows 2000 Professional and Windows Me, more adapted for the home user, in particular for gaming products. Essentially, Microsoft developed two families of operating systems in parallel - for home computers and for corporate networks, which were later found to be expensive and ineffective.

System Windows XP was created on the basis of Windows 2000, and various versions were developed for home and business users: Windows XP Home Edition and Windows XP Professional.

Keeping the core of Windows 2000, the Windows XP operating system has acquired a new appearance. Common tasks have been consolidated and simplified, and new visual cues have been added to assist the user in working with the computer.

In Windows XP, it became possible for multiple users working on the same computer to use the fast user switching function. This feature has been designed for home use. It allows each family member to work with the computer as if this computer was only at his disposal. Switching does not require the user who was previously working on the computer to log off and save the files they have opened.

The Windows XP family also includes a 64-bit operating system. Windows XP 64-Bit Edition designed for specialized technical workstations, whose users require the highest level of performance. This OS is designed for a 64-bit Intel processor.

Windows operating system advantages.

One of the advantages of the Windows family of operating systems is the support of the technology Plug & Play- a standard for hardware and software architecture that makes it possible to recognize devices. This technology makes it easier for the user to connect various external devices (scanners, printers, etc.)

Another advantage of these operating systems is their portability: due to special modules, the OS communicates with different hardware.

Windows operating systems implement preemptive multitasking method. This method allows the OS to "seize" the processor at any time, regardless of the running application. This allows you to kill the application if it hangs.

OS of the Windows family support the technology OLE(Object Linking and Embedding -connection and introduction objects). OLE- a standard that allows you to create various compound documents: in a document created by one application, you can embed or reference objects created by other applications. For example, in a document created by means of text Word editor, you can insert a table created in Excel.

The interface of the Windows family OS implements object model... Formally, an object is a collection of data and methods of working with them. Each object has its own properties. It is this model that allows the user to double-click on the icon of the desired file to open it, etc.

Windows family operating systems support PC online... This support is implemented in the following situations:

The OS supports client machine action for the most common server operating systems (Novell, etc.). This means that a computer with Windows OS installed on it can be connected as a workstation on a local network.

The OS can support different types of client machines at the same time, i.e. the computer can simultaneously support work in local and global networks.

The OS makes it possible to create peer-to-peer local networks. A peer-to-peer network is a network in which all computers are equal in their rights and users can access information stored on other machines, while there is no main machine on the network - the server.

All variety of software (software) is largely divided into systemic and application programs... The first group ensures the operation of the second on the available hardware (processor, disks, RAM, input / output devices). Operating Systems (OS) refers to system software... One of the tasks of the OS is to implement algorithms for working with hardware. The question may arise: why is this necessary? After all, if you think about it, each application can include code that provides access to the hardware. However, this would only make life difficult for programmers and bloat the software to a large size. And the saddest thing is that in application programs there would be a lot of the same code responsible for the implementation of low-level commands (calls to hardware). Besides, how to solve the problem of joint work of different programs on the same computer is another question. Therefore, operating systems and other system software quite reasonably occupy the role assigned to them as an intermediary between application software and computer hardware.

Even in their historical development, operating systems originated precisely as a set of programs and libraries for managing input and output operations. These fairly universal programs were further used by other programmers, who no longer needed to puzzle over how to program reading data from a floppy disk or outputting text to a printer. They just called a function from the connected library, and it did all the work (it already had the code for working with physical devices).

Over time, the operating system became more and more complex, new functions... Computers became more powerful, it was required to simultaneously run a certain set of programs for the processor to execute. The OS began to solve the problem of efficiently distributing hardware resources between running programs. Several users began to work with one computer at the same time. The OS began to monitor the rights of everyone and protect data. As a result, modern operating systems include many different features.

In their own way operating system structure presents a set of programs and modules. Allocate the concept of the operating system kernel. Software the kernel is protected from user and programmer interference. Application programs access the kernel using requests to perform one or another action with the hardware. These requests are called system calls and are special commands.

The purpose of the operating system

So, the operating system performs two main tasks:

makes it easier (or even empowered) for users and programmers to use the hardware. For example, an operating system makes it possible to abstract from how data is actually processed on a hard disk, and to work with the concept of a file.
ensures efficient use of hardware... Since more than one program is running simultaneously on modern computers, the OS is responsible for allocating memory, processor registers, etc. between running programs at every moment of time. The OS determines the optimal distribution of these resources in time (the use of the processor by programs in turn) and space (loading different programs into different parts of the RAM).

Windows family OS

Today, the most popular operating systems are the Windows family, which are a proprietary (commercial) product of Microsoft Corporation.

Windows begin its "pedigree" from the DOS operating system and originally represented shells built on top of it (Windows was launched from under DOS), increasing the capabilities of DOS and making it easier for an unprepared user to work with a computer. Already later versions (starting with Windows NT) were full-fledged operating systems.

The advantage of Windows is the user-friendly interface. Among the shortcomings, the unreliability of the system is noted.

Unix-like OS

The UNIX operating system has had a great influence on the development of the world of operating systems, laying the foundations for the work of modern operating systems. UNIX was originally a system for software development. Mostly programmers worked in UNIX (and indeed in the 70s, few others worked with computers).
UNIX has evolved from several fundamental ideas. For example, one small problem should be solved by one small program, and complex problems should be solved by a combination of simple programs.

In UNIX, much attention is paid to the distribution of computer resources between users. This system is multi-terminal (each user works with a computer using his own terminal).

Despite the fact that Unix-like systems are inferior in popularity to Windows, they work on large types of computers.

Linux

Linux is a multitude of Unix-like operating systems (distributions), which are most often freely redistributable.

One of the unique features of GNU / Linux systems is the lack of a single geographic center for development. Linux and its programs are written by millions of programmers around the world.

MAC OS

This operating system was also based on the UNIX kernel.

Is a product of Apple for its own Macintosh computers.

It is considered reliable and convenient. But unlike Windows, it is not so popular.

The operating system platforms Windows NT and Windows 2000 are operating systems for use on a wide variety of computers.

The Windows NT platform includes the following operating systems:

Windows NT Workstation

Windows NT for Workgroups

Windows NT Server.

The Windows 2000 platform includes the following operating systems:

Windows 2000 Professional

Windows 2000 Server

Windows 2000 Advansed Server

Windows 2000 Datacenter Server.

	Windows Professional	Windows Server	Windows Advanced Server	Windows Datacenter Server
Application area	Desktop computers, laptop computers	File server, print server, local network, network support	Business applications, e-commerce	Large Mission Critical Applications: OLTP, Data Warehousing, ASP and ISP
Number of processors supported by the system

All Windows operating systems are graphical multi-tasking systems.

Windows NT supports the FAT file structure and the new technology file system (NTFS).

Windows NT supports both RISC and CISC processor architectures.

Unlike earlier versions of Windows (such as Windows for Workgroups and Windows 95), NT is a complete operating system, not an add-on to the DOS operating system.

Microsoft Windows 98 is an updated Windows 95 operating system that enhances the functionality of your computer. The advantages of this OS :

Windows 98's Web-based user interface makes search easier by unifying the presentation of information across your computer, local area network, and the Web. (See chapters on the Internet).

Faster application startup times, new disk cleaners and more efficient disk performance.

An improved version of the File System Allocation Table (FAT32) allows you to increase the amount of free space on high-capacity hard drives by using it more efficiently. Converting the drive to FAT32 is done by a GUI program.

Windows 2000 was planned as an operating system to support the entire spectrum of computing technology - from laptops and desktops to clustered systems on high-end servers.

System Windows XP was created on the basis of Windows 2000, and various versions were developed for home and business users: Windows XP Home Edition and Windows XP Professional.

Windows operating system advantages.

Another advantage of these operating systems is their portability: due to special modules, the OS communicates with different hardware.

OS of the Windows family support the technology OLE(Object Linking and Embedding -connection and introduction objects). OLE- a standard that allows you to create various compound documents: in a document created by one application, you can embed or reference objects created by other applications. For example, in a document created using the Word text editor, you can insert a table created in Excel.

Windows family operating systems support PC online... This support is implemented in the following situations:

The OS can support different types of client machines at the same time, i.e. the computer can simultaneously support work in local and global networks.