The operating system ( SE , in English Operating System or OS ) is a whole of programs responsible for the connection between the material resources of a Ordinateur and the computer applications of the user (word processing, video game…). It provides to the programs applicatifs generic entrance points for the peripheral .
An operating system is typically made up:
- of a core;
- of libraries;
- of a whole of Tools system;
- of programs basic applicatifs.
The core of the system
See also: Core of operating system
The core (or heart) ensures the following functionalities:
- management of the peripheral (by means of pilot);
- management of the execution of the programs (also named process):
- management of the memory allotted to each process;
- scheduling of the processes (distribution of the execution time on the Processor S).
- synchronization and communication between process (services of synchronization, exchange of messages, pooling of segments of memory, etc)
- management of the files (by means of filesystems);
- management of the protocols network (TCP/IP, IPX, etc).
In these operating systems, the Random access memory is divided into two independent parts: the core and space user (this last are the space of the memory dedicated to the applications, which allows more safety: the applications of space user can neither accidentally nor intentionally reach a zone memory not belonging to them.
The cores have like basic functions to ensure the loading and the execution of the processes, to manage the input-outputs and to propose an interface between space core and the programs of space user.
The operating system, by this double structure core/user, generally makes it possible the applications to be independent of the machine on which they turn. The operating system thus masks the characteristics of each computer, by guaranteeing the interfaces necessary to the Compatibilité.
See also: software Library
The libraries are used to gather the operations most used in the Computer programs, in order to avoid the redundancy of the rewriting of these operations in all the programs.
One generally distinguishes two types of libraries: the utility libraries system, and libraries. The libraries system consist of functions allowing the pleasant use of the functionalities systems (generally of the entrance points towards functions of the core, but not only). The utility libraries contain functions of everyday usage and practical (mathematical functions, functions of sorting, etc).
From the point of view of the system the libraries have various characteristics. It is there the static or dynamic character, and shared or not.
A static library contains functions which will be integrated into the code generated by the compiler (static linkage editing). The disadvantage is that a code thus obtained is not updated when the library changes. The advantage is that the code with him alone is autonomous.
A dynamic library is a library which contains functions which will be integrated into the code at the time of its execution (dynamic linkage editing). The advantage is that the code is up to date with respect to the update of the libraries. The disadvantage is that the execution depends on the existence of the library. One refines also the dynamic aspect in late connection (integration of the function when it is called) or with the loading (integration of the functions as soon as the program starts to be carried out).
A divided library is a library of which it is guaranteed that the contents will be present only in one specimen in the system of execution, the functions will be divided by all the applications using them.
See also: Filesystem
A filesystem (FS or filesystem in English) or management system of files (SGF) is a structure of data making it possible to store information and to organize them in files on what one calls of the secondary memories (Hard drive, Disquette, CD-ROM, Clé USB, etc). This information storage is persistent. Such a management of the files makes it possible to treat, to preserve significant amounts of data like dividing them between several computer programs. It offers to the user an abstract sight on his data and makes it possible to locate them starting from an access path.
The tools system
The tools system allow:
- to configure the system (to manage the accounts of the users, configuration of the parameters network, automatic starting of the services, etc);
- to pass the relay to the applications proposing of the services to one or more users or to other computers, thanks to the network for example.
The graphical interface
See also: Graphical interface
This type of Interface man machine is opposed to the interface in Ligne of order (in English CLI for Command Line Interface ) like MS-DOS. The most typical parts of this type of environment are the pointer of mouse, the window S, the office, the icons. Moreover, graphic controls are used to interact with the user: the button S, finely S, the scroll bars. This interaction man machine is worked out that it is in the graphical interfaces or in line of order by the “Shell”. A Dispositif of pointing is necessary to the good performance of an graphical interface. This environment makes available and convivial a Ordinateur.
It is the visible part of the operating system, which explains why with each major change of its operating system, the manufacturers of operating systems make also evolve/move the graphical interface thus giving its identity to each generation of its operating systems.
The graphical interface is separated from the core. It is thus possible in certain operating systems to change or personalize its graphic environment (some Distributions Linux do not even have basic graphic environment). The interface of Windows XP is however also modifiable thanks to certain additional programs, this functionality not being included by defect.
The majority of the operating systems are equipped with an graphical interface, convivial, simple of use so much so that to use a Personal computer does not ask any more data-processing competences, but a small practice. Windows and Macintosh integrates tools system which manage the graphical interface: GUI (like Graphical To use Interface) as well as utilities of and system requirements file management. These functions are commonly regarded as naturally forming part of any operating system, which is not inevitably the case as certain versions GNU/Linux show it or of BSD. It is true that crushing it majority of the personal computers are equipped with operating systems whose graphical interface nativement forms part of the operating system.
Contrary certain operating system such OpenBSD voluntarily avoids including an graphical interface by defect. For reasons of speed or here of obvious safety.
The operating systems manage the graphical interface more and more in a vectorial way, with an aim of making the system even more convivial and dynamic (the Graphics card is in charge of posting 2D like 3D). These interfaces make it possible to benefit from made progress these ten last years in the chips 3D. The first system to integrate a vectorial interface was Mac OS X 10.2 with its Quartz engine. To date the interface 3D the most developed is Compiz-fusion, developed jointly by the creators of Compiz and Beryl, its Fork, functioning on GNU/Linux systems. The last version of Windows, Vista also integrates an office with an interface 3D, Aero.
The programs basic applicatifs
See also: Computer application
Programs applicatifs basic offer services to the user (computer, text editor, Navigateur Web, etc). These programs applicatifs are often provided in bundle with the operating system. Certain people estimate that they do not form really part of the operating system. Separation between the programs basic applicatifs and the operating system is difficult to define, owing to the fact that one becomes useless without the other, and that good number of applications are programmed by supposing that the programs basic applicatifs are always present.
A type of program heir to other operating systems
The Micro-ordinateur S are among the last generations of Ordinateur S. the operating systems which are dedicated to them were thus developed after the other types of operating systems (systems for central Ordinateur and Work station of which most known today is GNU/Linux). Another type of operating systems exists and was created after the personal computing: operating systems embarked.
The Years 1980
At that time the systems had neither the capacity nor the need for using the operating systems for minis and large computers. The first operating systems called monitors offered only very basic functionalities, and were generally charged since Read-only memory.
CP/M was one of the pioneers as regards operating system installed on a disc (and not on read-only memory). This operating system largely influenced the design of PC-DOS. This last, chosen by IBM like operating system for its first PC, made Microsoft one of the most profitable companies in the world. The principal alternatives during the Années 1980 on the market of the operating systems were OS/2 and Mac OS.
The Years 1990 and 2000
The end of the Années 1990 saw the requirements of the users increasing in term of reliability, safety and user-friendliness of the Graphical interface.
Thus Microsoft operated a migration of all its operating systems, including those intended for the general public towards the platform Windows NT, putting fine at the family of the Windows 9x.
During the same period, Macintosh completely reconsidered the core and the interface of its operating system while launching Mac OS X. The core is based on UNIX and the engine of posting of the Graphical interface, Quartz, is managed in vectorial Mode, offering one made new. Windows Vista roof its delay with its new named partially vectorial graphical interface Aero (this one not being provided in the basic version).
Lastly, the third actor of the operating systems is consisted the whole of the distributions Linux. Conceived and used by impassioned, its market shares in the field of the personal computers are largely minority (it is however difficult to accurately represent the market shares of a product which can be obtained free). He is on the other hand very present on the market of the waiters. For a few years Linux has opened to the neophyte with distributions like Ubuntu or Mandriva. This opening is successful so much on the commercial technical plan than since certain marks propose their computers general public with Linux (for example certain DELL are proposed with Mandriva or Ubuntu).
Platforms and operating system:
- Computers PC compatible: Mac OS (only those of Apple mark), Microsoft Windows and the simplest alternatives of Unix (Linux, BSD);
- Apple Macintosh before the passage to architecture PC: Mac OS, Linux and BSD.
The question of interworkingThe operating systems are not equal with respect to their Compatibilité on the various material platforms. Thus, Linux functions on many types of platforms, in particular the principal microcomputers: Macintosh and PC.
On the other hand, traditionally, the operating systems developed for Macintosh were not portable worms of other platforms, because of a policy of closing of the firm Apple. In corollary, the operating systems for “PC compatibles”, cannot use the Mac platforms (except the Linux distributions and BSD planned for these architectures: 68k and PowerPC).
Since January 2006, the architecture of the Macintosh was deeply modified: the Microprocesseur S are henceforth based on an architecture Intel (Mac-Intel) and either conceived by IBM - Motorola (PowerPC). The direct consequence was that Mac OS X had to be completely rewritten. In addition this modification of architecture processor makes it possible the Macintosh to enter the big family of “compatible IBM PC”. Thus, all the programs which are intended for the computers PC compatibles can henceforth run nativement on these new models, including the operating system Windows or the Linux distributions for PC.
On the other hand, the operating system Mac OS X cannot function on a computer of another mark: Apple integrated in its system a protection to prevent this type of illegal use. However, certain parts of the system Mac OS X not belonging at Apple (as the Darwin core) can legally function on all the computers PC compatibles.
most known operating systems:
OS/2 of IBM;
- OS/400 present on the average systems IBM (AS/400 - ISéries);
- Mac OS: the first operating system of the computers Apple Macintosh, which succeeded the systems LISA and APPLE II, and was followed of Mac OS X;
- VMS and OpenVMS (Compaq, ex- DIGITAL);
- Microsoft Windows, the operating system of Microsoft;
- Derived from UNIX (under various variations: BSD, System V, etc) of which:
- GNU/Linux : a free operating system being pressed on the core Linux and the tools GNU.
- the family BSD: an effort successful to return its freedom to the system of Berkeley including/understanding:
- NetBSD, OpenBSD and its derivative OliveBSD, FreeBSD and its derivatives, PicoBSD and DragonFly BSD, Darwin (on which is built Mac OS X, semi-owner).
- the UNIX owners :
- operating systems great systems ( Mainframe S ):
- Multics (father of UNIX) and heir to CTSS
- IBM: MVS, VM, DOS/VSE, TPF
- Bull: GCOS
- Siemens: BS2000
- ITS, TOPS-10 and TOPS-20
- Symbian OS is an operating system for Smartphones
- Error system
- Core of operating system
- List of the cores of operating systems
- List of the operating systems
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