Various operating systems. Types of operating systems

Among the many types and categories of software, operating systems are located at the very top of the hierarchy. These are large-scale and complex types of programs that act directly as a layer between the hardware of a computer or any other device and individual applications that help the user perform specific tasks.

The operating system must take control of all the main actions of the computer, as well as all peripheral devices. However, we cannot say that the OS exists only for PCs as such. Any complex electronic device that performs and calculates operations using a processor will need an operating system. Now there are special types of tablet computers, etc.

The operating system is necessary so that the user can manage all processes. This is a kind of shell that provides quick and convenient access to the main or device. It acts as an environment for running other applications and programs. Types are divided, first of all, by their properties and capabilities, as well as by the type of device for which they are intended.

OS features

As already mentioned, any one takes control of the hardware of a computer or any other device, controls the distribution of memory and processor performance. One of the main tasks is input and output of information, since any computer must work with new data.

There are types of operating systems with different types of file systems, as well as methods for processing processes, interacting with other machines, and using RAM. For the user himself, what remains noticeable first of all is the interface; the popularity of a particular OS, as well as the implemented methods, depends on how convenient it is.

We must not forget that the OS itself also takes up some available resources - RAM, processor power and disk space. Accordingly, the best operating system is one that has high functionality, but at the same time remains undemanding in terms of resources.

There are many types of operating systems, each of which has certain features depending on the tasks assigned. For example, some types of operating systems are designed to work in multi-user networks, others are designed for one user and one computer (OS Windows).

In relation to the user, one can distinguish such categories as convenience, interface, ease of administration, openness, cost, bit depth, etc.

Using his authority, the user can either remove the operating system or install a new one. However, this will be more difficult to do, since additional capabilities will need to be used. The operating system cannot remove itself.

In the current situation, we can distinguish types of OS for home computers and for mobile devices. In the first case, the leader is OS Windows from Microsoft. In the second case, the situation is somewhat different; for a long time there was no specific leader, but now it is a product from the Android OS. This is a fairly convenient operating system, with free code, and supported by a large number of content and software developers. In addition, the popularity of Apple devices explains the fact that the percentage of iOS is quite high. However, there are a huge number of other operating systems for computers and mobile devices that simply did not gain such high popularity or for some reason their development was suspended.

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Introduction

1.1 DOS limitations

1.2 System advantages

6.1 Options

6.2 New compared to Windows 2000

7.1 Innovations

7.2 Multimedia

7.3 Mobility

7.4 Security

8.1 BSD License

8.2 Birth of FreeBSD

8.3 Other BSD systems

Conclusion

Bibliography

Introduction

Today there are a large number of different types of operating systems, differing in areas of application, hardware platforms and implementation methods. Naturally, this also causes significant functional differences between these operating systems. Even for a specific operating system, the set of functions performed is often not so easy to determine; a function that is performed today by a component external to the OS may tomorrow become an integral part of it and vice versa. Therefore, when studying operating systems, it is very important to highlight from all the diversity those functions that are inherent in all operating systems as a class of products. A computer operating system is a set of interrelated programs that acts as an interface between applications and users on the one hand, and the computer hardware on the other. According to this definition, the OS performs two groups of functions:

1 providing the user or programmer, instead of real computer hardware, with an extended virtual machine, which is more convenient to work with and easier to program;

2 increasing the efficiency of using a computer by rationally managing its resources in accordance with some criterion.

In order to successfully solve their problems, a modern user or even an application programmer can do without a thorough knowledge of computer hardware. He does not need to be aware of how various electronic components and electromechanical components of a computer function. Moreover, very often the user may not even know the processor command system. The user programmer is accustomed to dealing with the powerful, high-level functions that the operating system provides.

So, for example, when working with a disk, a programmer writing an application to run under an OS, or an end user of the OS, only needs to represent it as a certain set of files, each of which has a name. The sequence of actions when working with a file is to open it, perform one or more read or write operations, and then close the file. Particulars such as the frequency modulation used during recording or the current state of the motor of the mechanism for moving the magnetic read/write heads should not concern the programmer. It is the operating system that hides most of the hardware features from the programmer and provides the ability to simply and conveniently work with the required files.

If the programmer worked directly with the computer hardware, without the participation of the OS, then to organize reading a block of data from the disk, the programmer would have to use more than a dozen commands indicating many parameters: the block number on the disk, the sector number on the track, etc. And after completion exchange operations with the disk, he would have to provide in his program an analysis of the result of the operation performed. Considering that the disk controller is capable of recognizing more than twenty different options for completing an operation, programming exchange with the disk at the hardware level can be considered not the most trivial task. The user's work would be no less burdensome if he needed to specify the numeric addresses of tracks and sectors to read a file from the terminal.

The operating system not only relieves programmers from the need to directly work with disk drive hardware by providing them with a simple file interface, but also takes care of all other routine operations associated with managing other computer hardware devices: physical memory, timers, printers, etc.

The operating system not only provides users and programmers with a convenient interface to the computer hardware, but is also a mechanism that distributes computer resources.

MS DOS is the most widely used operating system for personal computers. The number of application programs for MS-DOS is tens of thousands. There has never been such a large number of programs in the rapidly developing computer field. This variety of programs allows the MS DOS operating system to maintain a leading position among more advanced and more powerful operating systems. Naturally, this OS has its advantages and disadvantages.

1.1 DOS limitations

Without a doubt, the main distinguishing feature of computing systems of the 90s was the graphical user interface (GUI). Proponents of the GUI argue that this interface, focused on the direct visual perception of processed objects, greatly speeds up work with a PC and, due to its ease of learning, makes it more accessible to the mass consumer.

A more serious drawback is the limitation of the memory available to DOS programs - 640 K. In fact, DOS can use up to 1 Mb of RAM, but the IBM PC architecture reduces the available memory to 640 K. There are many workarounds - mapped memory, extended memory, DOS extenders , blocks of upper memory created by memory managers for the 80386 processor, but the fact remains that there is no natural way for application programs to use the megabytes of RAM installed on modern machines.

The only reliable way to overcome these barriers once and for all is to force the processor to run in protected mode. But neither DOS nor its application programs are capable of running in this mode, so huge spaces of expanded memory remain inaccessible to most programs.

The skeletal nature of DOS attracts software developers. Most major application programs communicate with the screen, keyboard, and printer, bypassing DOS, since the services it provides for organizing an interface with these and other devices are completely insufficient. DOS, for example, does not support interrupt-based serial I/O. Programmers spend a lot of time writing drivers for hundreds of different printers and video adapters. Hardware configurations vary so widely that it is difficult to write a program that will run on any IBM-compatible computer. Apart from the general file system, DOS can't help much here.

An application program written for Windows, on the other hand, will run on any PC that meets the stringent Windows requirements. Importantly, the responsibility for preparing drivers shifts from the software developer to the hardware manufacturer, so that the developer can devote more time to working on the core of the program.

It is not so easy to learn how to use various DOS programs. DOS doesn't have a standard interface for application programs, so what works in one program probably won't work in another. In order to write a file in a Windows program, just select Save from the File menu. In WordPerfect for DOS, you need to press F10 to start this process. In the Lotus 1-2-3 package - /FS. This list can be continued as long as you like. Research shows that the average IBM-compatible PC user regularly uses two or three application programs, while Macintosh users use almost twice as many. One possible explanation for this difference is that the similarity of Macintosh software makes it easier for a user to become familiar with one application to learn others.

Another "black ball" against DOS is the complete lack of multitasking. DOS is designed to run only one program at a time, and trying to make it work differently (except in some very specific cases) risks crashing the system. Even resident programs (TSRs), which are a limited but still very useful exception to the rule, complicate matters when they conflict with each other or with other elements of the system. There are a variety of products available from various companies that provide multitasking or task switching on DOS-based systems, but none of them can match the efficiency of an operating system such as OS/2, which from the very beginning was designed to run multiple programs simultaneously. .

1.2 System advantages

One of DOS's most obvious strengths is its moderate hardware requirements. In order to work with Windows at a more or less acceptable speed, you need at least a PC based on an 80386 processor with at least 4 MB of RAM. If necessary, DOS can work quite well with 640 KB on an 8088 processor. DOS programs run quickly, largely due to the fact that most of them use a text display mode. Even graphical DOS programs are usually several times faster than their Windows counterparts, since they are not dominated by GDI (Graphics Device Interface, a graphics device interface, a Windows component that is used by programs to display output to the screen). What one interprets as a disadvantage, another sees as an advantage.

The simplicity of DOS allows you to do things that are not possible in more complex operating environments. For example, you can use the DEBUG command to create very powerful utilities. The DOS API (application programming interface) is quite simple, and even novice programmers can learn to write useful programs. At the same time, the Windows API is very complex and takes several months to master. In addition, creating programs for Windows requires sophisticated tools, in particular resource editors, compilers and debuggers that run on this operating system. It's no coincidence that there is much less shareware and free software available for Windows.

The key idea of ​​Windows is to ensure that programs are completely independent of the hardware. Windows 3.1 was originally designed to completely handle communication with a specific type of display or printer. Both the user and the programmer creating an application for Windows are provided with universal tools that eliminate the problem of ensuring compatibility with specific hardware (hardware compatibility) and software (software compatibility). A unified, single graphical user interface makes it easy to learn new software products.

One of the means to ensure software compatibility is the mechanism for exchanging data between different applications. A special “mailbox” (clipboard) of Windows 3.1 allows the user to transfer information from one application to another without worrying about its format and presentation. Unlike professional operating systems, where the mechanism for exchanging data between programs is available only to the programmer, in Windows 3.1 this is done very simply and clearly for the user.

The mechanism for exchanging data between applications is a vital feature of a multitasking environment. And currently, software manufacturers have already come to the conclusion that one “mailbox” is clearly not enough to transfer data from one application to another. A new, more universal mechanism has appeared - OLE (Object Linking Embedded), which allows you to transfer heterogeneous data from one application to another.

Windows not only allows you to work with a familiar software product, but also offers additional features (running several programs at the same time, quickly switching from one program to another, exchanging data between them, etc.). The ability to work with all MS-DOS application programs (word processors, DBMS, spreadsheets, etc.) is provided.

Windows 3.1 can operate in one of three modes: Real, Standart, 386 Enhanced. During the installation process, Windows analyzes the available hardware resources and automatically sets the mode that makes the best use of the available hardware.

In real mode, Windows 3.1 does not use hardware capabilities not supported by MS-DOS (this mode is the only one possible on machines with an 8086/8088 processor): as in MS-DOS, the user is limited to 640 KB of RAM.

In standard mode (available on computers with an 80286 or 80386 processor), Windows 3.1 makes full use of the extended memory available on the computer, loading all applications written specifically for Windows there. DOS programs are loaded into regular memory.

In advanced mode (possible on computers with a processor 80386 and higher) when launching applications (both Windows and regular programs for MS-DOS), Windows 3.1 supports the so-called. virtual machine mode (the launched program is allocated its own computer with all the resources), implementing a multitasking environment.

Windows 3.1 allows you to run multiple programs at the same time (including the same program multiple times), with the ability to instantly switch from one program to another. This allows you to initiate a long process (printing, sorting and copying large amounts of data) and move on to other work rather than waiting for it to finish.

Windows 95 is an evolutionary development of Windows 3.1x and does not represent a complete break with the past. Although it brings many important changes over the 16-bit Windows architecture, it retains some of the most important features of its predecessor. The result was a hybrid OS capable of running 16-bit Windows applications, DOS-legacy applications, and legacy real-mode device drivers while being compatible with true 32-bit applications and 32-bit virtual device drivers. Among the most important improvements introduced in Windows 95 are its native ability to run 32-bit multi-threaded applications, protected address spaces, preemptive multitasking, much greater and more efficient use of virtual device drivers, and increased use of 32-bit storage heaps. system resource data structures. Its most significant drawback is its relatively weak protection against poorly functioning programs containing errors.

Each native Windows 95 application sees an unstructured 4 GB address space that houses itself plus the Windows 95 system code and drivers. Each 32-bit application runs as if it has exclusive use of the entire PC. Application code is loaded into this address space between the 2 and 4 Gb marks. Although 32-bit applications cannot see each other, they can exchange data via the Clipboard, DDE, and OLE mechanisms. All 32-bit applications run using a preemptive multitasking model based on individual threads. The thread scheduler, part of the virtual memory management (VMM) system, allocates system time among a group of concurrently executing threads based on an assessment of each thread's current priority and readiness to run. Preemptive scheduling allows for a much smoother and more reliable multitasking mechanism than the cooperative method used in Windows 3.1x.

Windows 95 system code is located above the 2 Gb limit. The space between the 2 and 3 Gb marks contains ring 3 system DLLs and any DLLs used by multiple programs. (Intel's 32-bit processors provide four levels of hardware protection, named Ring 0 through Ring 3. Ring 0 is the most privileged.) Ring 0 components in Windows 95 map to space between 3 and 4 Gb. These critical, highly privileged sections of code contain the virtual machine management (VMM) subsystem, the file system, and the VxD drivers.

The memory area between 2 and 4 Gb is mapped to the address space of each 32-bit application program, meaning it is shared by all 32-bit application programs on your PC. This organization allows API calls to be served directly in the application program's address space and limits the size of the working set. However, this comes at the cost of reduced reliability. Nothing can prevent a program containing a bug from writing to addresses belonging to system DLLs and causing the entire system to crash.

The area between 2 and 3 Gb also contains all the 16-bit Windows applications you run. To ensure compatibility, these programs run in a shared address space, where they can corrupt each other just as they did in Windows 3.1x.

Memory addresses below 4 Mb are also mapped into the address space of each application program and are shared by all processes. This allows compatibility with existing real-mode drivers that need access to these addresses. This leaves another area of ​​memory exposed to accidental writes. The lowest 64 of this address space cannot be accessed by 32-bit applications, which makes it possible to intercept invalid pointers, but 16-bit programs that may contain errors can write data there.

Windows NT is essentially a server operating system designed for use on a workstation. This results in an architecture in which absolute protection of application programs and data takes precedence over considerations of speed and compatibility. Windows NT's extreme reliability comes at the cost of high system costs, so a fast processor and at least 16 Mb of RAM are required to obtain acceptable performance. Like OS/2 Warp, Windows NT achieves lower memory security at the cost of not being compatible with real-mode device drivers. Windows NT runs native 32-bit NT applications, as well as most Windows 95 applications. Like OS/2 Warp and Windows 95, Windows NT allows you to run 16-bit Windows and DOS applications in its environment. programs.

The memory allocation scheme of Windows NT is very different from the memory allocation of Windows 95 and OS/2 Warp systems. Own application programs are allocated 2 Gb of special address space, from the 64 K border to 2 Gb (the first 64 K are completely inaccessible). Application programs are isolated from each other, although they can communicate through the Clipboard, DDE and OLE mechanisms.

At the top of each 2 Gb block of the application program is code that the application program perceives as ring 3 system DLLs. In reality, these are just stubs that perform call redirection, called client-side DLLs. When most API functions are called from an application program, client-side DLLs call Local Process Communication (LPC) procedures, which pass the call and its associated parameters into a completely isolated address space that contains the actual system code. This server process checks the parameter values, executes the requested function, and forwards the results back to the application program's address space. Although the server process itself remains an application layer process, it is completely protected from and isolated from the application program that calls it. Between the 2 and 4 Gb marks are the low-level Windows NT system components of Ring 0, including the kernel, thread scheduler, and virtual memory manager. System pages in this area have supervisor privileges that are specified by the processor's physical ring protection circuitry. This makes low-level system code invisible and unwritable to application-level programs but results in performance degradation during transitions between rings. For 16-bit Windows applications, Windows NT implements Windows on Windows (WOW) sessions. Like OS/2 Warp, Windows NT provides the ability to run 16-bit Windows programs individually in their own memory spaces or together in a shared address space. In almost all cases, 16- and 32-bit Windows applications can communicate freely using OLE (via special thunks if necessary) regardless of whether they are running in separate or shared memory. Native WOW applications and sessions run in preemptive multitasking based on individual thread control. Multiple 16-bit Windows applications in a single WOW session run using a cooperative multitasking model. Windows NT can also multitask multiple DOS sessions. Because Windows NT has a fully 32-bit architecture, there are no theoretical limits on GDI and USER resources.

The system was announced in 1994. Alpha testing was conducted from early 1995 to September 1997. The first public beta version of the system was released on September 27, 1997. The system was originally called Windows NT 5.0 because it was the next major version of Windows NT after Windows NT 4.0. However, on October 27, 1998, it received its own name, Windows 2000. The final version of the system was released to the general public on February 17, 2000.

Windows 2000 was released in four editions: Professional (for workstations and power users), Server, Advanced Server, and Datacenter Server (for use on servers). In addition, there is a "Limited Edition" of Windows 2000 Advanced Server Limited Edition and Windows 2000 Datacenter Server Limited Edition, designed to run on 64-bit Intel Itanium processors.

Windows 2000 was subsequently replaced by Windows XP (client side) and Windows Server 2003 (server side). As of 2005, Windows 2000 remained popular, especially in large companies where updating operating systems on a large number of computers poses serious technical and financial difficulties. As of early 2005, Windows 2000 had more than 50% share of Windows workstation operating systems in companies with more than 250 computers, according to research from Assetmetrix. At the same time, in companies with fewer than 250 computers, Windows XP is more popular.

5.1 Innovations compared to Windows NT 4.0

Some of the most significant improvements in Windows 2000 over Windows NT 4.0 are:

· Support for the Active Directory directory service. The Active Directory server side comes with Server, Advanced Server, and Datacenter Server editions, while full client-side service support is provided by the Professional edition.

· Internet Information Services version 5.0. Compared to IIS 4.0, this version includes, among other things, version 3.0 of the ASP web programming system.

· NTFS file system version 3.0 (also called NTFS 5.0 according to the internal version of Windows 2000 - NT 5.0). In this version of NTFS, support for quotas appeared for the first time, that is, restrictions on the maximum volume of stored files for each user.

· Updated user interface that includes Active Desktop based on Internet Explorer version 5 and is thus similar to the Windows 98 interface.

· Language integration: Previous versions of Windows came in three flavors - European languages ​​(single-byte characters, left-to-right only), Far Eastern languages ​​(multi-byte characters), and Middle Eastern languages ​​(right-to-left with contextual letter variations). Windows 2000 combines these capabilities; all its localized versions are made on a single basis.

Windows XP (code name during development - Whistler; internal version - Windows NT 5.1) is an operating system of the Windows NT family of Microsoft Corporation. It was released on October 25, 2001 and is an evolution of Windows 2000 Professional. The name XP comes from the English. experience.

Unlike the previous Windows 2000, which came in both server and client versions, Windows XP is a client-only system. Its server counterpart is Windows Server 2003. Although Windows Server 2003 is built on the same code as Windows XP, almost entirely inheriting its user interface, Windows Server 2003 still uses a newer and redesigned version of the NT 5.2 kernel; Windows XP Professional x64 Edition, which appeared later, had the same kernel as Windows Server 2003 and received the same security updates, as a result of which one could say that their development proceeded “in parallel.”

Microsoft has stopped free support for the Windows XP operating system (OS) since April 14, 2009; now Windows XP users will not be able to contact Microsoft for free technical support in case of incidents, for design changes, and in other situations. Now they will have to use “extended support” services for this - this means that all calls will become paid. Extended support will continue until April 8, 2014.

At the end of December 2010, Windows XP is the most widely used operating system in the world with a market share of 47.2%. The maximum of this value was 76.1% and was reached in January 2007.

6.1 Options

Windows XP came in many flavors:

· Windows XP Professional Edition was designed for businesses and entrepreneurs and contains features such as remote access to the computer's desktop, file encryption (using the Encrypting File System), central management of access rights and support for multiprocessor systems.

· Windows XP Home Edition - a system for home use. It is released as an inexpensive “stripped down” version of the Professional Edition, but is based on the same core.

· Windows XP Tablet PC Edition is based on the Professional Edition and contains special applications optimized for stylus input on tablet personal computers. The most important property is understanding handwritten texts and adapting the graphical interface to display rotations. This version is only sold with a matching computer.

· Windows XP Media Center Edition is based on the Professional Edition and contains special multimedia applications. The computer is usually equipped with a TV card and a remote control (RC). The most important feature is the ability to connect to a TV and control the computer via the remote control thanks to the simplified Windows control system. This system also contains functions for receiving VHF radio.

· Windows XP Embedded is an embedded component operating system based on Windows XP Professional Edition and is designed for use in various embedded systems: industrial automation systems, ATMs, medical devices, point-of-sale terminals, gaming machines, VoIP components, etc. Windows XP Embedded includes additional embedding features, including write protection filter (EWF and FBWF), boot from flash memory, CD-ROM, network, native system shell, etc.

· Windows Embedded for Point of Service - a specialized operating system based on Windows XP Embedded, configured for point of service and optimized for retail and service industries. Based on this platform, you can create an ATM, payment terminal, gas station, cash register, etc. Additionally, Windows Embedded for Point of Service includes POS for .NET technology for the rapid development of trading applications and support for trading peripheral equipment.

· Windows XP Professional x64 Edition - a special 64-bit version designed for processors with AMD64 Opteron and Athlon 64 technology from AMD and processors with EM64T technology from Intel. This system does not support processors from other manufacturers and does not work with the Intel Itanium processor. Although the first 64-bit processors appeared in 2003, Windows XP Professional x64 Edition was released only in April 2005. The main advantage of the system is its fast work with large numbers (Long Integer and Double Float). Thus, the system is very effective, for example, in performing floating-point calculations required in areas such as special effects for films and 3D animation, as well as the development of technical and scientific applications. This system supports mixed mode, that is, the simultaneous operation of 32- and 64-bit applications, but for this all drivers must be 64-bit. This means that most 32-bit applications can run on this system. The only exceptions are those applications that are highly dependent on computer hardware, for example, antiviruses and defragmenters.

· Windows XP 64-bit Edition - this edition was developed specifically for workstations with IA-64 architecture and Itanium microprocessors. This edition of Windows XP has been discontinued since 2005, after HP stopped developing workstations with Itanium microprocessors. Support for this architecture remains in server versions of the Windows operating system.

· Windows XP Edition N - a system without Windows Media Player and other multimedia applications. These versions were created under pressure from the European Antimonopoly Commission, which demanded that Windows XP be “lightened.” Currently, this distribution is aimed at developing countries. If desired, the user can download all missing applications from the Microsoft website for free. Available in both Home and Professional versions.

· Windows XP Starter Edition - a highly functionally limited version for developing countries and financially weak regions. In this version, only 3 applications can run simultaneously, and each application can create a maximum of 3 windows. The system completely lacks network functions, does not support high resolution, and does not allow the use of more than 512 megabytes of RAM or a hard drive with a capacity of more than 120 gigabytes. The system can run on Intel Celeron or AMD Duron processors.

· Windows Fundamentals for Legacy PCs - a stripped-down version of Microsoft Windows XP Embedded Service Pack 2 designed for legacy computers.

6.2 Innovations compared to Windows 2000.

Some of the most notable improvements in Windows XP over Windows 2000 are:

· New GUI design, including more rounded shapes and smoother colors; as well as additional functional improvements (such as the ability to display a folder as a slideshow in Windows Explorer).

· Support for the ClearType text smoothing method, which improves the display of text on LCD displays (disabled by default).

· Ability to quickly switch users, allowing you to temporarily interrupt the work of one user and log in as another user, while leaving the applications running by the first user enabled.

· Remote Assistance feature, which allows advanced users and technicians to connect to a Windows XP computer over a network to resolve problems. At the same time, the helping user can see the contents of the screen, conduct a conversation and (with the permission of the remote user) take control into their own hands.

· A system recovery program designed to return the system to a certain previous state (this feature is an extension of a similar program included in Windows ME), as well as improving other system recovery methods. So, when loading the last successful configuration, the previous set of drivers is also loaded, which in some cases allows you to easily restore the system in case of problems that arose as a result of installing drivers; ability to roll back drivers, etc.

· Improved compatibility with older programs and games. A special compatibility wizard allows you to emulate the behavior of one of the previous versions of the OS (starting with Windows 95) for a separate program. However, the compatibility feature is present in Windows 2000 Service Pack 2.

· Possibility of remote access to the workstation due to the inclusion of a miniature terminal server in the system (only in the Professional edition).

· More advanced system management functions from the command line.

· Windows Explorer support for digital photo formats and audio files (automatically displays metadata for audio files, such as ID3 tags for MP3 files).

· Windows XP includes technologies developed by Roxio that allow you to directly burn a CD from Explorer without installing additional software, making working with rewritable CDs similar to working with floppy disks or hard drives. Media Player also includes the ability to record audio CDs. The ability to work with disk images is not provided.

· Windows XP can work with ZIP and CAB archives without installing additional software. You can work with archives of this type in Explorer as with regular folders, which you can create and delete, enter the archive, and add/delete files just like working with regular folders. It is also possible to set a password for the archive. If necessary, you can assign any third-party software to work with these archives.

· Improvements in the EFS subsystem, consisting in the optional recovery agent, more secure key storage. Encrypted files are now not just deleted, but overwritten with zeros, which is much more reliable. Starting with SP1, it becomes possible to use (and is used by default) the AES algorithm, along with DESX and 3-DES.

· Customizable toolbars that help you optimize access to files, folders, and Internet resources. It is enough to place them on the edge of the Desktop (like a sidebar) or on the Taskbar (in the form of a link).

Windows 7 is an operating system in the Windows NT family, following Windows Vista. In the Windows NT line, the system has version number 6.1 (Windows 2000 - 5.0, Windows XP - 5.1, Windows Server 2003 - 5.2, Windows Vista and Windows Server 2008 - 6.0). The server version is Windows Server 2008 R2, the version for integrated systems is Windows Embedded Standard 2011 (Quebec), the mobile version is Windows Embedded Compact 2011 (Chelan, Windows CE 7.0).

The operating system went on sale on October 22, 2009, less than three years after the release of the previous operating system, Windows Vista. Although initially the operating system was supposed to go on sale on August 31, 2009. Partners and clients with a Volume Licensing license were granted access to RTM on July 24, 2009. The final unlicensed version (a copy from the discs that later went on sale) was available to everyone from the first days of August 2009.

Windows 7 included some developments excluded from Windows Vista, as well as innovations in the interface and built-in programs. The games Inkball and Ultimate Extras were excluded from Windows 7; applications that have analogues in Windows Live (Windows Mail, Windows Calendar, etc.), Microsoft Agent technology, Windows Meeting Space; The option to return to the classic menu and automatic docking of the browser and email client have disappeared from the Start menu.

7.1 Innovations

The operating system supports multi-touch control. This feature was first demonstrated by Microsoft at the annual TechEd"08 conference in Orlando. The demonstration used system build 6.1.6856, as well as a prototype laptop model with a multi-touch screen.

Branch Cache network technology allows you to cache the content of Internet traffic. If a user on the local network needs a file that has already been downloaded by someone on his network, he can get it from the local cache storage, rather than using a channel with limited bandwidth. The network cache can operate in two modes - Hosted Cache and Distributed Cache. In the first case, the file is stored on a dedicated local server running Windows Server 2008 R2; in the second case, a server is not required, and the cache is distributed for storage on user computers. The technology is designed for large networks and is offered for implementation in enterprises as part of the Corporate and Maximum versions of the OS.

Rice. 1 The Start menu in Windows 7 has become shorter and has lost its icons

The OS also has about 120 built-in wallpapers, unique for each country and language version. Thus, the Russian version includes the “Russia” theme with six unique high-resolution wallpapers. All versions include 50 new fonts. Existing fonts have been modified to display all characters correctly. Windows 7 is the first version of Windows to include more fonts to display non-Latin characters than to display Latin ones. The font control panel has also been improved - by default, it will display only those fonts for which the layout is installed in the system. Unicode 5.1 support has been implemented. The Instant Search search bar now recognizes more languages. An additional advantage of Windows 7 is closer integration with driver manufacturers. Most of them are detected automatically, while in 90% of cases, backward compatibility with Windows Vista drivers is maintained.

Windows 7 supports folder aliases internally. For example, the Program Files folder in some localized versions of Windows was translated and displayed with the translated name, but remained in English at the file system level.

Windows 7 is more compatible with Windows XP than Windows Vista (SP1, SP2), for example, it was impossible to run some old XP programs on Windows Vista.

7.2 Multimedia

The new, 11th, version of DirectX, first released as part of this operating system, has the following improvements: added support for new computational shaders, the ability to multi-threaded rendering, improved tessellation, new texture compression algorithms, etc.

Windows Media Player 12 received a new interface and became truly “omnivorous”, unlike its predecessor, which required a large number of codecs for playback. However, it cannot play licensed Blu-Ray discs with video, but it has the ability to read and write data to them.

7.3 Mobility

Although Windows Mobility Center hasn't changed much since Windows Vista, Windows 7 runs longer on laptops and uses less power, especially when playing DVDs. On a system introduced at the end of August 2009 with two identical laptops with pre-installed Windows 7 and Windows Vista, the gain was up to 20%. A record system loading speed was also shown - 11 seconds. The system included an SSD and other high-performance components. A similar test inspired enthusiasts to test the browser's impact on battery life. The Internet Explorer 8 browser included with Windows 7 showed the best results on the Intel platform.

However, according to the results of independent tests, it was found that Windows 7 drains a laptop's battery noticeably faster than Windows XP. Since August, experts from Laptop magazine (laptopmag.com) have been testing the final version of Windows 7, including measuring the battery life of portable PCs running it. The overall result was disappointing: the average netbook running the “Seven” generally runs 47 minutes less on battery power compared to the XP. In the case of the ASUS 1008HA model, the “shortage” was 57 minutes or 16.7%. Other publications also conducted similar studies and also came to these conclusions. The loss ranges from 10 to 30 percent in operating time.

A possible reason is that Windows 7 is optimized for graphics accelerators, while many netbooks run on integrated Intel and VIA graphics cards, which sometimes do not support Aero functions. Also, many netbooks run Windows 7 Starter Edition, which does not fully support Aero. Another possible reason is the lack of OS support from netbook manufacturers. So, with new drivers and BIOS dated November 2009, the Asus Eee 1000HA runs under Windows 7 for as long as it does under Windows XP.

Remote Desktop.

The Remote Desktop feature has also undergone changes. Support for the Aero Peek interface, Direct 2D and Direct3D 10.1 was introduced, support for multiple monitors, multimedia extensions, DirectShow, as well as the ability to play audio with low latency.

7.4 Security

Windows 7 implements a more flexible User Account Control (UAC) setting, which, unlike Windows Vista, has two more intermediate states between the “Always notify” and “Never notify” modes -- “Notify only when programs try to make changes to the computer "(default position), "Notify only when programs attempt to make changes to the computer (do not dim the desktop)." It's worth noting that, unlike Vista, dimming only occurs if the program is active and in the foreground. If you clicked while UAC was opening and deactivated the program, the blackout may not occur.

Changes have been made to the BitLocker encryption technology, and the BitLocker to go removable media encryption function has been added, which allows you to encrypt removable media, even in the absence of a TPM module.

Added the ability to protect data on USB drives using Enhanced Storage.

Improvements have also been made to the Windows Firewall - the function of notifying the user that a program that is trying to access the network has been blocked has returned.

Using Group Policy and AppLocker, you can prevent certain applications from running.

DirectAccess allows you to establish a secure connection to a server in the background, unlike VPN, which requires user interaction. DirectAccess can also apply group policies before the user logs on.

The likelihood of viruses, worms, and Trojans entering the Windows 7 system is 25% lower than in Windows Vista, and 20% lower than in Windows Vista SP2. In addition, on the 64-bit version of Windows 7, many viruses simply do not run.

Sandbox.

Windows 7 uses sandbox mode, the implementation of which was discussed during alpha and beta testing (during the Longhorn development stage). Access to low-level sockets for unmanaged code, as well as direct access to the file system, hardware abstraction layer (HAL), and full access to a memory address, are prohibited. All access to external applications, files and protocols is controlled by the operating system.

New Aero interface features

Aero Peek function

Shake

A new Aero Shake feature has been added to the Windows Aero interface, allowing you to minimize all inactive applications with a mouse movement. To activate it, just grab the window title and shake it a little.

Peek

The Aero Peek feature allows you to display smaller copies of windows when you hover over the taskbar icon, switch between application windows with a simple click on the icon, drag and pin various windows and applications to the taskbar, view the desktop with one hover to a special area of ​​the screen, and much more.

Snap

Similar to the Shake function, the Aero Snap function allows you to move the mouse to maximize a window half the screen, the entire screen, or only along the vertical axis.

FreeBSD is a UNIX-like operating system that is freely available on the Internet. It is widely used in ISP companies, embedded devices, and anywhere else where reliability is important. The FreeBSD operating system is the result of a continuous process of development, research and refinement over more than thirty years. The story began with the BSD project in 1979. BSD is the grandmother of FreeBSD. Many years ago, AT&T needed its own custom software to run its business. However, it did not have the right to invade the computer industry and therefore could not sell its software. As a result, AT&T provided various pieces of software and its source code to universities at a very low cost. Universities were able to save money by using this software instead of commercially priced ones, and university students had access to excellent technology. They could read the source code and study how it worked. In return, AT&T received a free platform for experimentation and a generation of computer scientists who grew up on AT&T equipment. Everyone was happy. The UNIX system was the most famous software distributed under this licensing plan. The original UNIX system had many disadvantages compared to modern operating systems. However, thousands of students had access to the source code, and hundreds of teachers needed interesting projects for their students. When programs didn't behave as expected, or bugs were discovered in the operating system itself, everyone who worked on the system day after day had the opportunity and incentive to correct those flaws. Thanks to their efforts, the UNIX system was soon improved and introduced many of the features that we now take for granted. Students added the ability to control the launch of programs (job control). The UNIX S51K file system made system administrators cry, so they replaced it with the Fast File System, a feature that has carried over into all modern file systems. Over the years, a large number of useful programs have been written, gradually replacing entire blocks of the UNIX operating system. The Computer Systems Research Group (CSRG) at the University of California, which contributed to these improvements, became the central repository for improvements to the UNIX code. The CSRG collected the changes, evaluated them, packaged them, and distributed the builds free of charge to all holders of a valid AT&T UNIX license. In addition, CSRG collaborated with the Defense Advanced Research Projects Agency (DARPA) to implement various functionality in UNIX, such as the TCP/IP protocol stack. The resulting collection of software was called Berkeley Software Distribution, or BSD. BSD users took software, improved it, and then brought their work back to BSD. Today we consider this method standard for developing open source software, but in 1979 it became revolutionary. Development took a long time. Looking at the copyright information for the old BSD system, you can see the following: Copyright 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994 The Regents of the University of California. All rights reserved. Yes, 15 years of work is a lifetime in software development. How many parts of the operating system not only continue to be used, but are actively developed after

15 years? In fact, so many changes were made to the original BSD system that over the years there was almost complete replacement of the original UNIX code with code created by CSRG staff and their assistants. There is very little left of the AT&T product. Eventually, CSRG funding ceased and it became apparent that further development of the BSD project was coming to an end. In 1992, after some debate within the bowels of the University of California, the BSD code was opened to the general public. This transfer of rights is called the BSD license.

8.1 BSD License

BSD code became available to everyone under perhaps the most liberal terms in the history of software development. Today the main provisions of the license look like this:

*Do not claim that you wrote this code.

* Don't blame us for errors in the code.

*Do not use our name to promote your product.

This means you can do whatever you want with the BSD source code. (The original BSD license required credit for using code released under the BSD license, but this requirement was later removed.) It doesn't even require you to share your changes with the original code's authors! Anyone is free to incorporate BSD code into proprietary, free, and open source products. The BSD code can be printed on punch cards and covered the lawn with them. Want to produce 10,000 CDs with the BSD operating system and give them to your friends? Please. Sometimes when discussing the BSD license the reference is not to "copyright" but to "copycenter" - "take this license to the copy center and print some copies for yourself." It's no wonder that some companies, like Sun Microsystems, have jumped on it—it's free, it's reliable, and there's a large number of certified technicians with experience using it.

A company called BSDi was even created specifically to take advantage of the benefits of BSD UNIX. AT&T/CSRG/BSDi Competition Even during the heyday of CSRG, work on UNIX continued at AT&T. AT&T took distributed pieces of BSD UNIX, integrated them with their UNIX system, and then re-distributed the result to universities, which made these improvements. This approach worked well until AT&T broke up and the resulting companies were allowed to compete in the software market. AT&T had one significant property: a high-end operating system that was fine-tuned by thousands of specialists from around the world. This operating system had many useful features, such as small but powerful commands, a modern file system, job control capabilities, and a TCP/IP protocol stack. AT&T formed its subsidiary, Unix Systems Labaratories (USL), which began successfully selling UNIX to enterprises for big money, while maintaining relationships with universities, which provided it with such an advanced operating system.

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Purpose and functions of the operating system.

Purpose of OS- organization of the computing process in a computer system, rational distribution of computing resources between individual tasks; 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 is a set of hardware and software necessary to connect peripheral devices to a PC) between the user and the computer, 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 ease of working with it, and its throughput. Different operating systems on the same hardware can provide the user with different opportunities for organizing the computing process or automated data processing.

OS features:

1) Scheduling tasks. CPU usage.

2) Providing programs with means of communication and synchronization.

3) Memory management.

4) File system management.

5) Input/output control.

6) Ensuring security.

Types of user interfaces of operating systems

Based on the type of user interface, a distinction is made between text (linear), graphical and speech operating systems.

A user interface is a set of techniques for how a user interacts with an application. The user interface includes the user's communication with the application and the language of communication.

Text OS

Linear operating systems implement a command line interface. The main control device in them is the keyboard. The command is typed on the keyboard and displayed on the display screen. The end of entering a command is pressing the Enter key. To work with operating systems that have a text interface, it is necessary to master the command language of this environment, i.e. a set of commands whose structure is determined by the syntax of that language.

The first real operating systems had a text-based interface. Currently, it is also used on servers and users' computers.

Graphics OS

Such operating systems implement an interface based on the interaction of active and passive graphical on-screen controls. The control devices in this case are the keyboard and mouse. The active control element is the mouse pointer - a graphic object whose movement on the screen is synchronized with the movement of the mouse. Passive controls are graphical application controls (on-screen buttons, icons, radio buttons, check boxes, drop-down lists, menu bars, etc.).

An example of exclusively graphical operating systems is the Windows family of operating systems. The start screen of such operating systems is a system object called the desktop. The desktop is a graphical environment on which objects (files and directories) and controls are displayed.

In graphic operating systems, most operations can be performed in many different ways, for example, through the menu bar, through the toolbar, through the window system, etc. Since operations are performed on an object, it must first be selected (selected).

The basis of the graphical user interface is an organized system of windows and other graphic objects, when creating which developers strive for maximum standardization of all elements and working methods.

Window - This is a framed rectangular area on the monitor screen in which applications, a document, or a message are displayed. A window is active if the user is currently working with it. All operations performed in graphical operating systems occur either on the Desktop or in some window.

Speech OS

In case of SILK interface(from the English speech - speech, image - image, language - language, knowledge - knowledge) - on the screen, following a speech command, a movement occurs from one search image to another.

It is expected that when using the public interface there will be no need to understand the menus. Screen images will clearly indicate the further path of movement from one search image to another along semantic semantic connections.

Scheduling tasks.

Task Scheduler - Microsoft Management Console (MMC) snap-in, which includes additional Help topics for advanced users.

Task scheduler is a program or operating system service that launches other programs depending on various criteria, such as:

the arrival of a certain time

the operating system enters a certain state (inactivity, sleep mode, etc.)

An administrative request has been received through the user interface or through remote administration tools.

Microsoft Windows

In versions of Windows up to and including XP, this service was provided primarily for the needs of the end user. Starting with Windows Vista, this service is actively used by the operating system itself for maintenance (defragmentation of hard disk partitions, testing components, indexing files, etc.).

Cron- task scheduler daemon in UNIX-like operating systems.

Organization of input-output.

When the processor encounters an I/O-related instruction while executing a program, it executes it by passing the corresponding commands to the I/O controller. In programmable I/O, this device performs the required action and then sets the appropriate bits in the I/O status registers. The I/O controller no longer sends any signals to the processor, including interrupt signals. Thus, it is the processor's responsibility to periodically check the status of the I/O module; it must check until the I/O operation completes.

Backoff Processor

A very rare option and not entirely unambiguously interpreted. BOFF# (Back Off) - signal to unconditionally disconnect the processor from the bus. Based on this signal, the processor gives control of the bus in the next cycle, interrupting the current cycle. When the "BOFF#" signal expires, the processor restarts the interrupted bus cycle. Possible option values:

"Disabled" (or "No"),

"Enabled" (or "Yes").

Based on all of the above, we can assume that the option refers to the unconditional transfer of bus control to another device, i.e. without setting different waiting intervals, certain control transfer conditions, etc. This will be discussed in detail below (the topic of “arbitration”). It is clear that to use the specified signal, the option must be enabled.

The option may be called "Backoff CPU".

Base I/O Address

Option to set the base address of the device. I/O addresses are input/output addresses, also called ports of system and peripheral devices. Essentially, these are “mailboxes” through which programs and devices exchange messages and data. Each address is allocated one byte of system memory. Since the 386 systems, there are 65,536 such addresses available, although most of them are never used.

The base I/O address is the first address in the address space provided to the device. For example, most network adapters use an address range of 20h, and for COM 1 a range with addresses from 3F8h to 3FFh is reserved, which are used for various tasks, for example, setting speed, parity, etc. The entire I/O address range is 0000-FFFFh.

No specific values ​​are provided for this option. And in terms of content, the option is more “suitable” for materials devoted to the distribution of resources of various devices. But the option is placed in this place deliberately to emphasize that the I/O addresses belong not only to memory, but also to the central processor. After all, it is from this that control procedures begin, and they are carried out through the input/output ports.

If you look at the “Ports” chapter, you will notice that the existing addresses are already “assigned” to system or peripheral devices. But when programming an I/O device, and this may be an expansion card, it is quite acceptable to use “traditional” addresses or unused ones. In some cases, the use of unused addresses, due, for example, to the absence of a device, does not necessarily lead to conflicts.

The "Extended I/O Decode" option discussed above showed us some of the nuances and even difficulties of decoding I/O addresses. The "PCI I/O Start Address" option, generally intended for PCI devices, nevertheless allows you to create an additional address area for ISA devices and thereby avoid "unpleasant overlays".

Branch Target Buffer

Simply a rare feature, more in the sense of uniqueness rather than frequency of appearance in different BIOS versions. What is it about? BTB (Branch Target Buffer - jump address buffer) is a central processor unit responsible for dynamic branch prediction. In this case, it takes into account which transition addresses were previously selected. This is the most important component of a modern processor (see specialized literature).

It turns out that using this option you can refuse (“Disabled”) from using the mechanism for predicting transitions and branching processor commands or enable it (“Enabled”). It remains to add that enabling the option improves system performance.

CPU ADS# Delay 1T or Not

Option to set delay for ADS# signal. A few preliminary words. ADS# (Address Status) - address strobe entered by the exchange initiator as an indicator of address validity. The signal operates on the system bus and can be output from both the processor side and the chipset side. The address and address strobe are transmitted simultaneously, since the system bus has its own dedicated line for the address strobe. It is clear that ADS# is a standard processor signal.

The presented option also indicates the possibility of no delay, which increases the speed characteristics of data exchange in the system. In fact, this option allows you to set the time during which the processor (or chipset, memory controller) will wait from the chipset (processor) for a data address status signal, which determines the lazy write speed on the system bus. It is clear that we are also talking about data transfer to the PCI interface. The default value does not need to be changed. However, if you install a faster processor, the speed can be increased, i.e. remove the delay.

The option in the header has two meanings: "1T", "No Delay".

But the “Cyrix M2 ADS# delay” option offered the standard “Enabled” and “Disabled”. The "Latency from ADS# status" option suggested numerical values ​​in system bus clock cycles: "2T" (default), "3T".

It is necessary to understand that by setting the “delay time”, we thereby determine the timing characteristics of the recording cycles. And taking into account the fact that the use of a deferred write buffer leads, as a rule, to the formation of small packets (double words or two DW). Therefore, by setting it to "3T", we get 5 system clocks for each double word. The arithmetic here is simple. 3 delay clocks, one address clock and one read clock.

CPU BIST Enable

In some chipsets, starting from the 430 series, specialized BIST registers have been used. They didn't carry much load. If the system (chipset + processor) supports the Built-In Self Test function, then the BIST register stores the “Start BIST” or “Completion Code” commands in its bits. If the “system” does not support BIST functions, then setting the option to “Enabled” will have no effect, and the corresponding bits of the register will be set to “0”.

A built-in and, importantly, full-fledged BIST self-testing mechanism was implemented in Pentium III processors. It provided constant monitoring of freezes and failures in microcode, large programmable logic arrays, and also provided testing of the instruction cache and data cache, TLB buffers (Translation Lookaside Buffer) and ROM memory segments. Within 10-30 ms (the time is related to the internal frequency of the processor core), internal testing covers about two-thirds of all internal processor blocks. Only after the test is completed, the processor goes into operating mode, and the test results are recorded in the EAX register.

CPU Drive Strength

This and not entirely clear option determines the intensity (strength), or rather the duration of the signals, when transferring data from the chipset to the processor. The parameter is measured in system clock cycles. The higher the value of the parameter, the longer the duration of the signals, and the use of this “BIOS Setup” option may be useful for “overclocking” procedures of processors. But not for every system, increasing the option values ​​can lead to maintaining the stability of the “overclocked” processor. The option values ​​are as follows: 0, 1, 2, 3.

It remains to add that this option requires additional clarification.

CPU Fast String

- (fast string operations). Enabling this parameter (“Enabled”) allows you to use some specific features of the architecture of the Pentium Pro processor family (Pentium II, Deschutes, etc.), in particular, the ability to cache string operations. You just need to understand that the conditions for enabling this mechanism must be met in the user program itself. These conditions are specified in the documentation for any processor of this family. It is recommended to leave the parameter in the "Allowed" state.

CPU Line Read Multiple

This option refers to the processor reading the so-called. "full cache" lines. When the cache line is full of data, its volume is 32 bytes (eight double words). Since the line is "full", the system knows exactly how long it will take for the data on the line to be read. The system will need 4 clock cycles for this, after which a new address will be set. Therefore, the system does not require a signal to end data transfer, and the system will not wait for such a signal, being free to perform other tasks. When the option is "Enabled", the processor will be able to read data simultaneously from several "full cache" lines. The default is "Disabled".

The option may be called "CPU Multiple Reads".

The functions listed below do not contain multiplicity properties, but their placement in this location is more than justified. Here are their names: "Allow Full Line Reads", "Full Cache Line Reads", "CPU Line Read". Each of them, through "Disabled" or "Enabled", prohibits or allows the use of "full" read lines.

The "CPU-to-PCI Read-Line" option has "On" and "Off" values, but the differences don't end there. An option under this name was introduced and optimized to work with Intel OverDrive processors. Therefore, improved CPU efficiency can only be achieved with the specified processors. Otherwise the option should be disabled.

CPU Read Multiple Prefetch

Option to enable/disable multiple prefetch mode. The meaning of the prefetch process is that the processor, selecting the desired instruction (for example, from the PCI bus or memory), simultaneously begins to read the next one, thereby initiating the next process. This is facilitated by the fact that the chipset can have four read lines. For example, the first chipsets supporting Pentium Pro processors (Intel 450KX/GX, both codenamed Orion) had 4 such read lines. Multiple prefetching allows you to perform several instruction fetch operations simultaneously, which significantly increases system performance. The default is "Disabled".

The option may also be called "CPU Multiple Read Prefetch".

If we are not talking about “multiple” operations, then the option may be called “CPU Line Read Prefetch”, “CPU Read Prefetch”.

I/O Space Access

This option, via "Enabled", allows access to the entire I/O address space. Rarely does a BIOS do without strange options.

Processor Number Feature

An option to set the automatic reading and display of information about the built-in serial number of the Pentium III processor in the BIOS of motherboards that support its installation. To implement this feature, of course, the parameter value is “Enabled”. In all other cases, the value is set to "Disabled". It is also installed by default.

The option may be called "Processor S/N".

In the "Phoenix BIOS" there is a similar option called "CPU Serial Number", and in the "AMI BIOS" - "Processor Serial Number".

Why is serial number information needed? Let's say, for external programs. One example is reading information about the processor when surfing the Internet. Naturally, this violates the user's privacy and rights. At one time, this problem was discussed quite vigorously.

OS file system.

The file system is a part of the OS that includes:

1) The totality of all files on the disk.

2) Sets of data structures used to manage files.

3) A set of system software tools that implement various operations on files.

FS functions:

1) File naming.

2) Program interface for applications.

3) Mapping the logical model of the file system onto the physical organization of data storage.

4) File system resilience to power failures.

File types:

1) Regular files are files containing arbitrary information that is entered into them by the user, or generated as a result of the operation of system and user programs.

2) Directories are a special type of file that contains system reference information about a set of files that are grouped by users according to some informal criterion.

3) Special files are files associated with system input/output devices that are used as a mechanism for accessing individual files and external devices.

Modern file systems support other file types: symbolic links; named pipelines; memory-mapped files, etc.

Microsoft still ships its LAN Manager networking OS. A large number of independent vendors have licenses for this OS and support their own versions of LAN Manager as part of their networking products. These companies include such well-known firms as AT&T and Hewlett-Packard. LAN Manager requires installation of the OS/2 operating system on the file server; workstations can run under DOS, Windows or OS/2. OS/2 is an operating system that implements true multitasking, running in protected mode on x86 and higher microprocessors. LAN Manager uses a 32-bit version of the OS/2 file system called HPFS, which is optimized for file server use by caching directories and data. LAN Manager is the first network OS designed to support a client-server environment. The key components of LAN Manager are the redirector and the server. LAN Manager is particularly effective at supporting client-server architectures for database management systems. LAN Manager allows workstations running OS/2 to support peer-to-peer network service. This means that the workstation can serve as a database server, print server or communications server. The limitation is that only one user other than the owner of that workstation has access to such a peer-to-peer service.

For work in a small network, Microsoft offers a compact Windows for Workgroups operating system that does not require significant hardware or software costs. This operating system allows you to organize a network using a peer-to-peer scheme, without the need to purchase a special computer to work as a network server. This operating system is especially suitable for solving networking problems in teams whose members previously used Windows 3.1 extensively. Windows for Workgroups achieves high network processing performance due to the fact that all network drivers are 32-bit virtual drivers.

Computers with the image of a seven-colored apple have long ceased to be a curiosity. They can now be found almost everywhere - in publishing houses, advertising agencies, design studios. The high popularity of Apple computers among layout designers and designers can be explained by many reasons, but the high quality, user-friendly interface and reliability of this brand’s equipment are noted by everyone. The company is approaching the new millennium confidently occupying a worthy place among the largest computer manufacturers. New developments based on PowerPC 750 (G3) processors have already gained well-deserved popularity, and Apple is preparing to release even more powerful computer models equipped with a reliable and convenient MacOS operating system. One of the latest models, the iMac, has become a hit of the season, breaking all sales records. The distinctive features of this computer are high computing power, ease of installation and configuration, elegant design at low cost.

The original philosophy for Unix development is to distribute functionality across several small parts, programs.

This was originally a requirement coming from the hardware that Unix originally ran on. For some strange reason, the resulting operating system turned out to be quite useful on other hardware. You can achieve new functionality and new capabilities relatively easily by combining small parts (programs) in a new way. If new utilities appear (and they do), you can build it into your old toolkit. Unfortunately, these days, Unix programs are becoming larger and include more and more features, but some flexibility and interoperability still remain. For example, when I wrote this document, I was actively using these programs; fvwm is for managing windows, emacs is for editing text, LaTeX is for formatting it, xdvi is for viewing formatted text, dvips is for preparing it for printing, and finally lpr is for printing. If I find a new, better dvi viewer tomorrow, I can use it instead of the old one without changing any other settings.

Network OS.

Network OS – designed for processing, storing and transmitting data in an information network.

Tasks:

Resource sharing;

Network administration.

Are divided into:

Network OS for servers;

Network OS for users.

Network OS forms the basis of any computer network.

Under network OS:

In a broad sense: is understood as a set of operating systems of individual computers, interconnected for the purpose of exchanging messages and sharing resources according to uniform rules - protocols. These protocols provide the basic functions of the network: addressing objects; functioning of services; ensuring data security; network management.

In a narrow sense: Network OS is the OS of a separate computer that provides it with the ability to work on a network.

Divided into classes:

Peer-to-peer (the same OS is installed);

Two-rank (more often called networks with dedicated servers).

Deadlock situations.

Deadlock (clinch, deadlock)- a situation that will never be resolved, i.e. the process is waiting for a resource, but it will not be allocated to it.

The OS is in a deadlock state ("hung") - when several processes are in a deadlock state.

Simple OS deadlock:

Let there be 2 processes A and B, which, before starting work, are provided with resources P1 and P2, respectively. At some point in time, process A needed P2, and process B needed P1, but they will not receive them, because they are held by previous processes => there is a simple deadlock in the OS.

Rules for preventing deadlocks in the OS:

Before a process can begin running, it must be provided with all the required resources.

In the event that it needs an additional resource during operation, it needs to return all previously allocated OS resources and then request all the required resources with this additional resource.

Endless delay of the process.

In a system where processes have to wait until it allocates the required resource, a situation may arise that processes with a higher priority will come and require the same resource - a situation of endless delay of the process.

In some operating systems, this situation is prevented by increasing the priority ("aging" the process so that it is given the required resource, after which the priority is lowered to the previous level.

Resource management.

The idea that the OS is primarily a system that provides a user-friendly experience is consistent with a top-down view. Another view, from the bottom up, gives an idea of ​​the OS as a mechanism that controls all parts of a complex system. Modern computing systems consist of processors, memory, timers, disks, magnetic tape drives, network communications equipment, printers and other devices. According to the second approach, the function of the OS is to distribute processors, memory, devices, and data among processes competing for these resources. The OS must manage all computer resources in such a way as to ensure maximum efficiency of its functioning. The efficiency criterion can be, for example, the throughput or reactivity of the system. Resource management involves solving two general tasks that do not depend on the type of resource:

resource planning- that is, determining to whom, when, and for divisible resources and in what quantity, it is necessary to allocate a given resource;

resource status tracking- that is, maintaining operational information about whether a resource is busy or not, and for divisible resources - how much of the resource has already been distributed and how much is free.

To solve these common resource management problems, different operating systems use different algorithms, which ultimately determines their overall appearance, including performance characteristics, scope, and even the user interface. So, for example, the processor's control algorithm largely determines whether the OS is a time-sharing system, a batch processing system, or a real-time system.

Types of operating systems. The concept of an operating system.

Operating system (OS) is a set of system and control programs designed for the most efficient use of all resources of a computer system (CS) (Computer system is an interconnected set of computer hardware and software designed for processing information) and the convenience of working with it.

Batch processing operating systems.
A batch operating system is a system that processes a batch of jobs, that is, several jobs prepared by the same or different users. Interaction between the user and his job during processing is impossible or extremely limited. Under the control of a batch processing operating system, the computer can operate in single-program and multi-program modes.
Time sharing operating systems.

Such systems provide simultaneous service to many users, allowing each user to interact with their task in a dialogue mode. The effect of simultaneous servicing is achieved by dividing processor time and other resources between several computing processes that correspond to individual user tasks. The operating system provides a computer to each computing process for a short period of time; If the computing process has not completed by the end of the next interval, it is interrupted and placed in a waiting queue, giving way to another computing process. The computer in these systems operates in multiprogram mode.
A time-sharing operating system can be used not only to serve users, but also to control technological equipment. In this case, the “users” are individual control units for actuators that are part of the technological equipment: each unit interacts with a specific computing process for a time interval sufficient to transmit control actions to the actuator or receive information from sensors.
Real-time operating systems.
These systems guarantee prompt execution of requests within a given time interval. Requests can come from users or from devices external to the computer, with which the systems are connected via data transmission channels. In this case, the speed of computing processes in a computer must be consistent with the speed of processes occurring outside the computer, i.e., consistent with the flow of real time. These systems organize the management of computing processes in such a way that the response time to a request does not exceed specified values. The required response time is determined by the properties of the objects (users, external devices) served by the system. Real-time operating systems are used in information retrieval systems and process equipment control systems. The computer in such systems often operates in multitasking mode.
Conversational operating systems.
These operating systems are widely used in personal computers. These systems provide a convenient form of dialogue with the user through the display when entering and executing commands. To execute frequently used sequences of commands, i.e. jobs, the dialog operating system provides batch processing capabilities. Under the control of an interactive OS, the computer usually operates in single-program mode.

Today, a huge part of the world's population interacts with computers on a regular basis, some are obliged to work, some look for information on the Internet, and some simply spend time playing games. Everyone has their own needs, which means the computer must meet them. And if we are talking about “hardware” (the technical component of a computer), then everything is more or less clear: the newer, the better. But the “software” part requires special attention.

Each computer runs 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, an important factor is the choice of this operating system.

There is a fairly massive list of operating systems, but this article will focus on three pillars that have greatly influenced the industry and occupy the largest share among all operating systems: Windows, MacOS and Linux.

Proprietary operating systems

To begin with, it’s worth clarifying that there are proprietary operating systems, those that are distributed under a manufacturer’s license. These include Windows, the list of which is given below, and MacOS. Despite the fact that both systems can be downloaded on the Internet (stolen), the correct 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 OSes 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, so in most cases the quality of the 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 concerns the super-successful release of Windows 7. The list of Microsoft operating systems goes back a dozen generations. They are extremely popular all over the world and occupy almost 90% of the market. Which speaks to unprecedented leadership.

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

The list intentionally 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 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 own pros and cons, it often becomes 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 it) 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 semi-automatically and can be done by any user.

Apple computers have a special utility - BootCamp, which is designed for simple and seamless installation of Windows next to MacOS.

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

Instead of a conclusion

The list of operating systems for a computer is not limited to the above. There are a lot of products from different companies, but they are all quite specific and do not deserve the attention of the average user. The choice is worth making between Windows, MacOS and Linux, as they can cover most of the needs and are quite easy to learn.

Types of operating systems. A single-user system is an operating system that does not have the properties of a multi-user system. Examples of single-user operating systems are MS DOS from Microsoft (USA) and OS/2, created jointly by Microsoft and IBM. Multi-user system - a computing system or part of it (for example, an operating system) that allows several users to simultaneously access one computer from their terminal (local or remote).

Multitasking OS - an operating system and computer in which one processor can process several different programs or different parts of one program simultaneously. In this case, all programs are kept together in RAM and each is executed for a certain period of time. The most common multitasking system is Unix Single-tasking OS - The OS for the first microcomputers was also single-tasking; these include CP/M, MS-DOS, PC-DOS, etc. Types of operating systems.

Network operating systems Network operating system, NOS (Network Operating System) is an operating system designed to ensure the operation of a computer network. Examples of network operating systems are Windows NT, Windows 2000, Novel Netware, Unix, Linux, etc.

Today, the most well-known operating systems are Windows, Mac OS and the Linux family of operating systems. Windows is the most popular system in the world. 91% of users in the world use Windows operating systems. Mac OS is the second most popular operating system in the world. The total share of users in the world is about 5.4%. Linux family – This OS has gained the greatest popularity in the market of smartphones with Android OS (64%) and among Internet servers.

A family of proprietary operating systems. Microsoft Corporation, focused on the use of a graphical interface for management. Initially, Windows was just a graphical add-on for MS-DOS. The first Windows 1.0 OS was released in 1985 by Microsoft Corporation. The corporation was originally called MICROcomputers SOFTware and was founded by Bill Gates and Paul Allen.

As of May 2013, according to the Netmarketshare (Net Applications) resource, about 91% of personal computers are running operating systems of the Windows family. Windows operating systems run on x86, x86-64, IA-64, ARM platforms. Recently, Microsoft Corporation has been actively producing mobile devices based on Windows, but so far they have not been able to surpass Android and Apple in popularity

Mac OS (Macintosh Operating System) is a family of proprietary operating systems with a graphical interface. Apple wanted the Macintosh to be presented as a computer "for everyone else." The term "Mac OS" itself didn't really exist until it was officially used in the mid-1990s. Apple was also the first to invent and use the computer mouse. Which has become a very popular device.

In 1984, Apple Computers introduced the Macintosh computer with the Mac OS 1 operating system. Users controlled their computer not only with commands and instructions entered from the keyboard, but also using a then new device called a mouse.

Early versions of Mac OS were compatible only with Macintoshes based on Motorola 68k processors, later versions were compatible with the PowerPC (PPC) architecture. Recently, Mac OS X has become compatible with x86 architecture. But Apple's policy is that it only allows Mac OS to be installed on their computers.

The general name for Unix-like operating systems based on the kernel of the same name. The Linux kernel and the components commonly used with it are created and distributed according to the free and open source software development model. Therefore, the generic name does not imply any single "official" Linux package; they are usually distributed (often free of charge) in the form of various ready-made distribution kits that have their own set of application programs and are already configured for the specific needs of the user.