Operating Systems

Welcome to my Operating Systems. An operating system (OS) is software to handle computer hardware plus software possessing and provide for general services because of computer programs. The operating system is an indispensable element of the method software in a computer method. Application programs generally are in need of an operating system to function.

An operating system (OS) is the program product on a data machine, and it assigns the various resources available in the data machine to other programs. One type pressure's peripherals are, as one writer. The operating system fits for example of two programs simultaneously send information the same type, but they issued on a regular on a waiting list before. An annex type resources are internal enter as a Past and processors. This is hard components of the operating system also keeps track of.

One can betray program product as stream be one av two types:  or system program product. Applikasjonsprogramvare is such things as word processors, spreadsheets and other programs are broken have direct contact with. A system program item is the operating system's most important. It keeps track of system resurgence and makes programs the job simpler. Tilleggsenheter coupled to the data machine is often broke. A hard disk, for example, teenagers on stream start the engine's, stop it, move on gestodene and myeloma other things. The operating system Bruker hard drive by commutated find just a standard Maate with a driver application layer of Xian. An annet program that wants y not write to the hard drive gives just to the operating system, for example, " write the text 'Kongle' to file" kongle.txt. The operating method, in collaboration with the driver program, tar seg av as the rest of.

The operating system is a program that everyone else in the data machine. It is written in a programmeringsspråk and follows the usual rules for applications. The difference is that it is the first to be loaded in in the main net when the machine is started, and it controls the 'everyday life' for all programs loaded in later.

Usual operating

Microsoft Windows is the av the most made use operative system for personal computers. Its forløpere came beginners introduction av 1980's with MS-DOS from Microsoft and DR-DOS from Digital Research. The acronym DOS stands for Disk Operating System.

Unix is amongst the oldest operative system as for that is. The free operating system Linux bleed also for personal computers, but special servants, supercomputers, and for broker Elektronika. Linux is a avert av Unix. Amongst other Unix variants fins we Berkeley Software Distribution (BSD).

IBM had a period generate success with sit OS / 2, and Macintosh machines Bruker Mac OS (formerly quite simply cal system). New Macer kjører However, Mac OS X, which is BSD secure and encrypted.

background

A modern computer system consists of components which processor, bells, in- and with me. The operating system keeps track of componentizing and gives an approach to them. This Maaten does not need every program kennel to by a Burke the often complex inherent or how an application should share these with other programs. The operating system can be seen in which a layer which separates applications program Varen from the often more complex mechanical goods.

Different computers broker various types of machinery products. An application has written for one type of data the machine will then not necessarily kjøre on an annex. However, an operating system fines for several types of machines, something which makes the operating system acts as a joint platform one application can use seg av, turn a Tenke on the various types machine product broken can Tenkes on ha. Kjente operating systems.

Operating systems can be grouped into several mater. An audiovisual them are banquets Bruk comrade. Large machines have operating systems adapted to their break, mini equipment site and servants have its operating systems. Joint for all these is that they have no interaction with broken as the focus. On the desktop or in private homes fins we as former Kaltes microcomputers, later home data machine and so PC. These have their own operating systems and from late 1980 century diaper Microsoft's operating systems market leader there. Handheld enter as PDAs and mobile phones have operating systems that are spelled adjusted to machine the product. An annex category oozes is sanctioned operative system. These site agencies offer services where they guarantee response time. Examples are data machine that controls tuning and drivstofftilførsel in a modern car.

As well as the system event in lending, which is the keenest, fines also several alternative operating systems. Amongst these fins we BeOS, which no longer demands a becomes violet, but it's several new operating systems during which are clones av or Inspired av BeOS, an av these is Haiku. Other alternative operating systems during is Syllable and.

Also contemporary major technological mobile phone Bruker operating system. Usually, these were quite primitive, but banquets each as mobile games have stronger and received a grant of more bruksområder also mobile Telefon operative system also bliss tubside. This is particularly something which has come while and camera mob figures. Examples of operating systems for mobile are: Symbian, Windows CE, Linux, Android, IOS

History

    Provide in-depth article: Operating system history

The world's first data engineer, Charles Babbage mechanical "analytical machine" from the 1800s, made use is not an operating system. Babbage made use most majority av life and his fortune on stream get this stream work but turn bigger generate success as contemporary mechanical elements not had precise as provides. Etter, this was the listen to frame for around other World War, where amongst other things, Howard Aiken, John von Neumann, pioneer J Presper Eckert and William Mauchly in the US and Konrad Zuse in Germany put computers which filled the entire ROM  av vacuum. These diapers built programmers and drifted av the same group of people, and had not one å operating talk about. All programming in maskinspråk, often by å plugin in wiring in the hull. Then y sin all the machines these prob flows solved best av simple arithmetic, such as syrup large tables y av sine and cosine.

In the 1950s diaper transistor opponent and  Amended seg radically. Well, diaper the different people who to respectively, begging, programming and drifting av and programs diaper stored on as the various could take with seg down in data grommet and kjøre. Programmeringsspråk as Fortran emerged also opp. Since myeloma time with the stream prey, treat thrifter and the like, so you briskly to a better system strengths. This diaper where a stack diaper lest inn on magnetic tape and been driven banquets as data machine diaper free. Often it was several computers involved, one who was good at å else and write tape and one who was good at å kjøre arithmetic (for example respectively IBM 1401 and IBM 7094).

A typical job is to illustrate in the figure menu on the right. The best av an input card, a card with  about huh which had to be loaded, a number of cards as innholder program, a card which said data machine program which just was compiler had to be loaded in, a card which said data machine that the program should kjøres , a sett cards with data that should bleed during kjøring and a card that told to stack the cards were concluded. Kontrollkortene can be seen on as a forefinger to today skriptspråk and command interpreter. 

Today

Modern operating systems usually have a drawing device using a graphical user interface (GUI), and as an additional mouse or touch panel input device and so different from the keyboard. The old OS or performance-oriented Server usually do not have such kind of interface, but the command-line interface (CLI) plus a keyboard as an input device. These two interfaces are in fact so-called shell, its function is to accept and process user commands (such as pressing a button, or at the command prompt, type the command column).

Choose to install the operating system and its hardware architecture is usually a great relationship, only Linux and BSD can be performed on almost all architectures, and Windows NT only ported to the DEC Alpha and MIPS Magnum. In the early 1990s, selecting, PCs had to be limited to the Windows family, Linux and Unix-like family, and to Linux and Mac OS X as the most important alternative choice until today.

Mainframe and embedded systems use very diverse operating systems. There are many recent mainframes begin supporting Java and Linux to share resources other platforms. Recent embedded systems contending for Sensor Networks from Berkeley Tiny OS used to be able to operate both Microsoft Office for Windows CE.

Personal computer

PC market is divided into two camps, there are two architectures support this operating system:

    Apple Macintosh - Mac OS X, Windows (Intel platforms only), Linux, BSD.

    IBM compatible PC - Windows, Linux, BSD, Mac OS X (informal support).

Large computer

The first operating system is the main structure for large developers in the 1960s, since these systems have made a huge investment in software, so the original computer manufacturers to continue to develop compatible with the original operating system, hardware, and operating systems. This early operating system is a modern operating system pioneer. Now still supported mainframe operating systems include:

Modern Mainframe also typically run Linux or Unix variants.

Embedded Systems

Embedded system is widely used an operating system (such as Vx Works, eCos, Symbian OS and Palm OS) and some reduced functionality versions of Linux or other operating systems. Under certain circumstances, OS alleged is a built-in application software giant fixed the generic program. In many of the Simplest embedded system, called OS means its only application.

Main article: Unix -

The so-called Unix-family refers to a family of a wide variety of OS, this family contains a System V, BSD, and Linux. Forasmuch as Unix is a registers trademark of The Open Group, especially a company to comply with this definition of the behavior of the operating system. The Unix-usually refers to more than the original Unix contains features OS.

Unix-like systems can be very multi-processor architecture executed on the server system has a high utilization rate, such as universities or engineering workstation applications.

In 1991, the Finnish student Linus Torvalds based on Unix-like Minix prepared and released a Linux operating system kernel, and thereafter at Richard Stallman recommends GNU General Public License, a free software Unix variants. Linux has recently become increasingly popular, they are also great gains on the desktop personal computer market, such as Ubuntu system.

Some Unix variants, such as Hewlett-Packard's HP-UX and IBM's AIX only design their own hardware products are used, and the SUN Solaris can be installed on its own computer hardware or x86. Apple's Mac OS X is a number from NeXTSTEP, Mach, and FreeBSD derived from common microkernel BSD systems, this OS replaces the early Apple Computer non-Unix family of Mac OS.

After several years of clutter and free and open source Linux system gradually eroded in the past in the field of professional software patents, such as a conventional computer animation operation giant ── Silicon Graphics (SGI) IRIX systems have been designed for Linux family and Bell Labs research team nine No plan and Inferno systems substituted, expressions are used to disperse the environment. They are not like other Unix systems, choosing instead built the graphical user interface. Nine original plan is not popular because it is not free software just launched. Later, after the change in the free and open-source software license, Lucent Public License released, we began to have the majority of the users and community. Inferno was sold to Vita Nuova and GPL / MIT license release.

At present, the computer ranked according to the computing power of the World 500 472 units using Linux, 6 station uses Windows, the rest is all kinds of BSD and other Unix. [Citation needed]

Main article:

Microsoft Windows family of operating systems for IBM is based on Microsoft's MS-DOS machine design based on the design of the graphical operating system. Now Windows systems, such as Windows 2000, Windows XP are all built on a modern Windows NT kernel. NT is the core of the OS / 2 and OpenVMS systems borrowed. Windows can run on 32 and 64-bit Intel and AMD processors, but earlier versions can run on DEC Alpha, MIPS and PowerPC architectures. Although the open-source operating system for people interested in upgrading, Windows market share declined, but by 2004, Windows operating system in the world occupies 90% of the desktop operating system market. 

Windows systems can also be used on low-end and mid-range servers, and database support services web services and some other functions. Microsoft recently spent a great deal of research and development funds for causing Windows has the ability to run a large enterprise of the program.

Windows XP on October 25, 2001, release, August 24, 2004, released Service Pack 2, 2008. April 21 released the latest service pack 3. On a Microsoft operating system Windows Vista (codenamed Longhorn) on January 30, 2007, sale. Windows Vista adds many features, especially system security and network management capabilities, and it has a gorgeous interface Aero Glass. But overall, its reputation in the global market, but not very good. Its successor, Windows 7 is on October 22, 2009, sale, Windows 7 improves performance issues criticized Windows Vista, compared to Windows Vista, in the same hardware environment, Windows 7 performance compared with Windows Vista as well. The latest Windows 10 is on July 29, 2015, sale.

 

Operating on this type  FMS (Fortran Monitor System) and IBSYS, IBM site operating system for 7094 model.

At the beginning introduction av 1960, the figure had most presenter two sett products; a data series of machines for Bruk to talk using one a data series of machines for Bruk to leasing and sorting av data. This first type diaper operation on Vitenskap and calculations, and the other diaper Bruk a banks and.

Apple Mac OS

Main article: Mac OS and Mac OS X

Mac OS is a series that runs on Apple Macintosh computer's operating system. Mac OS is the first success in the commercial area of the graphical user interface system. Macintosh group including Bill Atkinson (Bill Atkinson), Jef Raskin (Jef Raskin) and Andy Hertzfeld (Andy Hertzfeld). 10.8 Start withdrawn from Mac OS X in the name and keep only OSX version number. The latest version of the current system is OS X v10.11.2.

Chrome OS

Main article: Google Chrome OS

Google Chrome OS is a lightweight computer operating system, Google plans based Google browser Google Chrome Linux kernel.

other

Mainframe and embedded operating systems are Unix or Windows family with little to do, in addition to Android, Windows CE, Windows NT and Windows XP Embedded Windows are the blood products, as well as several embedded Linux and * BSD suite exception.

Few older OS today still in need of some stability in an active market, such as IBM's OS / 2 [4], BeOS and XTS-400.

After the dot-com era frenzy, as few people, AmigaOS and RISC OS such as the use of the OS still continued to build to meet the community and special fanatic professional users.

An excellent operating system is sure to have the ability to make various levels of users meet the various needs of the visualization toolkit is simple and efficient programming environment to program to create a program, such as legal norms to guide legislation to create a new bill. This is actually a part of the operating system implies, you can determine how strong expansion capability. For example, an operating system with a corresponding Developer Toolkit is an integrated environment program and visualization, but also the ability to make a person look not too high can understand, for modifying a voice synthesizer contains spectral display, but if does not support the operating system itself does not provide the tools available program, it will become very complicated, it is possible to achieve this goal, the developers will be ready a variety of related utilities, and even to write their own set of related utilities Create a special kit, finally, check the code. If someone wants to generate staves through music, read music to correspond to similar rules about markup language, a variety of timbre, pitch and acquisition concluded a set of rules, voice recognition can be identified by instrument category, etc., and then mark the music breaks complete the transition from sound to music and production. But the human voice is more complicated but also unnecessary so. If the need to reproduce the sound using the sound waveform, no relevant toolset is quite difficult to achieve, the only other sound using the same set of rules generated by the waveform drawing a waveform diagram for sound reproduction is the original sound.

Sold as a commodity in the history of the operating system software is often because the browser contains a media player in the United States suffers antitrust prosecution, so that almost functionally incomplete. Few operating system software to provide more comprehensive App and utility programs.

Compile operating system software also requires corresponding compiler environment.

On the same computer running a different operating system software, it is possible in different ways to use computer resources. For example, running on Mac OS X and Windows in two different technologies OpenCL, Core Image: DirectX graphics card to use to achieve a similar effect.

Image recognition and voice recognition to search for information.

To meet the different needs of the required degree of precision fine division of time, and scale segment can interconnect, synchronization, coordination had to be coordinated by a number of personal cooperation to complete at any time to adjust and control operations synchronized with each other, which must have immediate messaging display, visual configuration script for coordinating synchronization schedule tasks and perform the complete assembly of such scheduled task.

future

Research and establishment of the future operating system still engaged. Operating system towards providing more power, network-based, easy to use, gorgeous UI direction to improve. Class UNIX OS and the desktop environment by developers collaborate, trying to make their own use to improve the environment.

eye OS is a practical network cloud computing operating system.

GNU Hurd is a totally compatible with Unix and strengthens many of the features of the micro-architecture core objectives. Singularity is a Microsoft.Net and establishes the foundation for better memory protection mechanisms for the research project objectives.

Features.

The operating system is located between the user and the underlying hardware, is a bridge between the two. Users can through the operating system's user interface, enter the command. The operating system then interprets commands, driving hardware to achieve user requirements. Modern standards, a standard PC operating system should provide the following functionality:

    Process Management (Processing management)

    Memory management (Memory management)

    File System (Filesystem)

    Network Communications (Networking)

    Security (Security)

    UI (User interface)

    Driver (Device drivers)

Process Management

Main article: Process and thread

Whether TSRs or apps, they are in a stroke of standards units. When then built using the von Neumann architecture computer, each central processor can only execute one stroke at the same time. Earlier operating system (such as DOS) does not allow any program to break this limit, and DOS only while executing a process (although they claim they have a DOS terminate-and-wait-resident (TSR) capability and can be partially solved this difficult problem). Modern operating systems, even with only a CPU, you can also use multiple processes (multitask) function to execute multiple processes simultaneously. Process management refers to the operating system to adjust the stroke of a plurality of functions.

Since most computers contain only one central processing unit, in single-core (Core) in the case of multi-stroke simply quickly switch each stroke, so that each stroke capable of performing, multi-core or multi-processor under the circumstances All travel through much collaborative technology transfers in each processor or core. The more simultaneous stroke, the stroke of each can be assigned to the smaller proportion of time. Many operating systems in the face of this situation problems will arise such as sound or intermittent mouse tabbing (called crash (Thrashing), an operating system that can not discontinue the shaping of their program arrangement and exhaust system resources of the state, other users or hardware programs are unable to perform). Travel management has usually practiced the concept of time-sharing, most of the operating system can assign different privilege levels (priority), to change the time-sharing proportion for each trip. The higher the privilege of travel, the higher execution priority, the proportion of the higher unit time occupied. The interactive operating system also provides some degree of feedback mechanism to allow the user to interact directly with the stroke has a high privilege value.

In addition to the travel management, the operating system still assumes the inter-process communication (IPC), travel aborts the more abstruse and deal with the problem of deadlock (Dead Lock) detection and treatment.

There are problems in the thread under the stroke, but most of the operating system and does not deal with the problems encountered thread, usually only limited to the operating system provides a set of API allows users to manage their own operations or through the mechanism of virtual machines interaction between the control execution thread.

Memory Management

Accordingly Parkinson's rule: You give in the project more memory, the program will try every means to run out," so programmers usually want the system to give him unlimited and infinitely fast memory. Most modern computers are hierarchical memory architecture, the fastest and the least number of registers headed, then cache memory and the slowest disk storage devices. The operating system's memory management provides for an available memory space, configuration and release memory space and exchange contents of memory and slow storage devices ...... functions. Such has been called virtual memory management features dramatically increase the stroke of each available memory space (usually 4GB, even though the amount of RAM is actually far less than this number). However, this also brings the disadvantages of slightly reduced efficiency, and can also cause serious and even stroke collapse.

Another focus of activity by the memory management is to help the CPU to manage the virtual location. If there is a lot of travel is stored on a storage device, the operating system must prevent them from interfering with each other's memory contents (unless through certain agreements operating under the scope of control and limit the range of accessible memory). Split memory space can achieve their goals. Each trip will see the entire memory space (from 0 to the maximum limit of memory space) is arranged to its own (of course, some positions are reserved and prohibited access to the operating system). CPU previously saved several tables than with the actual location of the virtual memory location, this method is called paging (paging) configuration.

With each stroke produced separately from the position of the space, the operating system can also be easily released once occupied by a trip all the memory. If the trip does not release the memory, the operating system can end the trip and the memory is automatically released.

Disk and file system

Main article: File System

The so-called file system, generally alleging disk data management system, data can be to type directory or file storage. Each system has its own file format and special features, such as log management or disk without reforming.

The operating system has many built-in file system. For example, Linux has a very wide range of built-in file systems such as ext2, ext3, ext4, ReiserFS, Reiser4, GFS, GFS2, OCFS, OCFS2, NILFS with Google file system. Linux also supports non-native file systems, such as XFS, JFS, FAT family, and NTFS. On the other hand, Windows file system can support only FAT12, FAT16, FAT32, exFAT and NTFS. NTFS on Windows systems are the most reliable and most efficient file system. Other than family FAT NTFS old, and for the length of the split files have very limited disk capacity, thus causing a lot of problems. The UNIX file system is mostly UFS, and a branch of UNIX Solaris recently begun to support a new kind of ZFS.

Most of the above file system has two build methods. The system can build a log or non-Journaled. Journaling file system may be a safer way to perform system response. If you do not have a journaling file system build encounter sudden system crashes, resulting in the establishment of the information in half a standstill, this system requires a special file system check tool to recover; journaling can automatically reply. Microsoft NTFS and Linux's ext3, ext4, ReiserFS, and JFS are journaling file systems.

Each file system implementation similar directory/subdirectory structure, but there are many similar to different points. Microsoft uses "\" symbol to create the directory/subdirectory of the relationship, and its file name Ignore case differences; UNIX system is based on "/" create a directory structure and file names are the cases there are differences. (In fact, this is the system call to see, "/" or "\" does not actually exist Drive)

The internet

Many modern operating systems with the mainstream Internet Protocol TCP / IP the ability to operate. This means that such operating systems can access the online world, and as sharing files, printers and scanners and other system resources.

Many operating systems also support multiple network protocol network in the past and the brightest of the Age of Enlightenment, such as IBM created SNA, DEC in its production system set DECnet architecture and Microsoft Windows for a particular protocol produced. There are many special features for research and development of protocols, for example, provide access to the NFS file system on the web. Now used extensively for video streaming (Streaming media) agreements game and UDP messages sent.

Safety

Most operating systems contain some level of information security. Information security is mainly based on two concepts:

    The operating system provides a direct or indirect access to external resources of several pipelines, such as the local end of the drive's file system privilege protected call, service programs and user privacy data performed by the system has to offer.

    An operating system has the ability to request certification resources access. Allow authenticated insistence and can not refusal illegal request and appropriate powers authorization (Authorization) to this request. Some systems authentication mechanism only briefly put resources into privileged and non-privileged, and each request has a unique identity identification number, such as the username. Resource requests are usually divided into two types:

        Internal sources: a resource request is usually a program being executed issued. In some systems, once a program executable can do anything (such as DOS virus era), but usually, the operating system will give a program identification number, and a request in this program, check the code and resource requirements the access relationship.

        External sources: from non-local resource request from the client computers, such as the remote login local computer or a certain network connection request (FTP or HTTP). In order to identify these external requests, the system may make this request certification requirement. Typically requests a username and the corresponding password. Sometimes it kind of system authentication methods such as magnetic or biometric data will be applied. In some instances, such as the communications network, usually without access to the resources (for example, anonymous access to FTP servers or P2P services) certification.

In addition to allowing/deny the form of security, a high level of security of the system will provide a recording option that allows recording various requests for access to resources of behavior (for example, "who had read this file?").

Prompted by military and commercial organizations will record sensitive information on the computer security mechanisms in the operating system is a long history of concern and discussion. US Department of Defense (DoD) will be the creation of a "trusted computer system assessment of the program" (TCSEC), this guide set up the performance evaluation of the basic principles of security mechanisms. On this operating system, it is very important, because the TCSEC was used for evaluation, classification and selected out for processing, storage and access to sensitive or confidential information of the computer system's standard procedures.

Internal communications security

Internal information security can be seen as a means to prevent the program being executed any access to system resources. Most operating systems allow ordinary programs can directly operate the computer's CPU, it creates some problems, such as how to be such as operating systems, like processing transactions, perform the same special instruction programs forced to stop, after all, in this scenario, the operating system is just another a program on an equal footing. As a general-purpose operating system produced by the CPU on a hardware level generally practice a degree of protection concepts special instructions. Generally, lower privilege level program you want to execute certain commands is blocked, such as direct access to an external device like a hard drive or the like. Therefore, the program must have asked, via the operating system, the operating system to perform special commands to access the disk. So the operating system will have the opportunity to check for identification of this program, and so to accept or reject its request.

On the special instructions not supported hardware architecture, and the other is the only method of protection, it is the operating system does not directly use the CPU executes the user's program, but by providing a simulation of a CPU or p-Code System (pseudo code execution machine), such as Java allows program execution on the virtual machine.

Internal security is especially important in multi-user computer: the system allows each user to have their own individual files and directorship, and other users can not enter or delete any. Because any program could bypass the operating system monitoring, are more likely to bypass the monitoring logger, with a force of internal security mechanism starts when skimming it is also very important.

External communications security

Usually, a job will be provided (hosted) services for the computer or other users on the web. These services are usually digital access point by the operating system or network address of the port after the offer. This service typically includes providing file sharing (NFS), print sharing, e-mail, Web services and file transfer protocol (FTP). External forefront of information security, such as a firewall and other hardware devices. Within the operating system often set up many kinds of software firewall. Firewall software can be set to accept or reject on the operating system to perform a service connection with the outside world. So anyone can install and perform some insecure network services, such as Telnet or FTP, and set their own use, except for certain channels to block all other connections, in order to reach a mechanism attempts to prevent bad connection.

User Interface

Today, most of the operating systems include a graphical user interface (GUI). There are several types of older operating system graphical user interface and core closely, such as Windows and Mac OS earliest implementation products. Such techniques may provide a more rapid response capability of the graphics, and the implementation time without cutting module thus more labor, but there is a strong side effect, such as graphics system crash will cause the entire system to crash, such as blue screen of death. Many modern modular operating system, the sub-system graphic interface separate from the core (known in Linux and Mac OS X originally was designed as such, and some extended version of Windows finally adopted this approach).

Many operating systems allow users to install or create anything they like graphical user interface [5]. Most Unix and Unix-derived systems (BSD, Linux, and Minix) often install X Window System with GNOME or KDE desktop environment. And some operating systems are not so flexible graphical user interface such as Windows. Such operating systems only through additional programs to change the graphical user interface, or even only part of the change [citation needed] such as menu style or color configuration.

The graphical user interfaces with the times, such as when each new version of Windows will be listed on the graphical user interface a new look, and the Mac OS GUI is also a significant shift when OS X Listed Mac.

driver

Main article: Drivers

The so-called driver (Device driver) refers to a class designed to interact with the hardware of the computer software. Usually, a device designed to improve the interaction interface, the use of computer communication subsystem sink drain or connected with this hardware, providing functionality for this device ordered and receiving information; and the final destination, the message to the operating system or applications. Drivers for specific hardware and operating system-specific design software, usually in the form of operating system kernel modules, application software packages or ordinary computer program executed under the operating system kernel to achieve a smooth and transparent interaction with the hardware effect, and provides in handling asynchronous time-dependent interface (asynchronous time-dependent hardware interface) required hardware interrupt handler (interrupt handler).

The main purpose of the design is that the driver operation abstraction, any hardware modules, even if the same kind of device, there is a huge difference in the design surface of the hardware as well. Manufacturers introduced the newer modules are usually more reliable and more efficient control methods will be different. Computer and its operating system often cannot be expected that the variation of the existing and new devices cannot be aware of its method of operation. To solve this problem will usually take the initiative to develop the operating system means that some of each mode of operation, and driver behaviors that sucked function operating system developed by description, translated into allowing the device to know the custom operating practices.

Theoretically, suitable driver Once installed, the new device corresponding to could be executed. The new driver allows this device to fit perfectly in the operating system so that users are not aware of the original operating system does not function.

structure

Operating Systems theorists sometimes the operating system is divided into four parts:

    Driver - the lowest level of direct control and monitoring of various types of the hardware part of their responsibility is to hide the details of the hardware and to provide the rest of an abstract, common interface.

    Kernel - the core part of the operating system, typically runs at the highest privilege level, is responsible for providing the basic structural features.

    Supporting libraries - (also known as "Interface Library") is a series of special libraries, their duty is to the programming interface to basic services packaged into the application system provided that can be used (API), it is the closest part of the application. For example, GNU C runtime libraries fall into this category, it is the various operating system's internal programming interface packaged into the form of ANSI C and POSIX programming interface.

    Perimeter - the so-called peripheral, refers to all other parts of the operating system other than the above three categories, typically serve particular advanced service components. For the sample, in the micro-kernel shape, most system services, as well as UNIX / Linux various daemons have normally classified this column.

Of course, the concept of four structures proposed in this section is also not-fits-all. For example, in the early Microsoft Windows operating system, the degree of coupling between the various parts of the deep, difficult to distinguish from each other. In the outer core structure using an operating system, then there is no concept of the driver. Thus, the discussion in this section applies only to the general, specific exceptions require specific analysis.

Most of the operating system Four different layouts also formed the distinction of several overall structures. Common structures include simple structure, layer structure, micro-kernel structure, vertical structure, and virtual machine architecture.

classification

The operating system does not have a single standard classification, can be divided into batches according to the operating system works, time-sharing operating system, real-time operating systems, network operating systems and distributed operating systems; architecture can be divided according to single-core operating system; depending on the operating environment can be divided into desktop operating systems, embedded operating systems; according to the length of the instruction is separated into 8 bit, 16 bit, 32 bit, 64 bit operating method.

The kernel is the core of the most basic components of the operating system, its structure often has a certain degree of influence on the external characteristics of the operating system and applications. Despite With the evolution of theory and practice, the coupling has the potential to narrow the growing operating system kernel level features and structures, but the habit is a common core structure is still a standard operating system of classification.

Core structure can be divided into single-core, micro-kernel, AMD core, outer core, and the like.

The single-core structure is the core component of the operating system, each hetero then mixed form, the structure produced in 1960 (also the early 1950s, says that there are still controversial), the oldest, is separated from the operating system kernel and peripheral when original form.

Microkernel architecture is generated out of the 1980s newer kernel structure, emphasizing the separation of structural components and functional components. 20th century, based on micro-kernel architecture, theory, it also developed a variety of ultra-fine structure of core and outer cores. Although since the 1980s, most studies have focused on the theory of micro-kernel, led by the "new" structure, however, among the applications, a single-core architecture-based operating system has been dominated.

Among the many popular operating systems, in addition to QNX and Mach-based UNIX systems and a few other, almost all single-core structure, such as most Unix, Linux, and Windows (Microsoft claims that Windows NT is based on a modified micro-kernel architecture, although there are objections to this theory). Microkernel and Advanced Micro kernel structure is mainly used for research operating system, there are some embedded systems use the outer core.

Based on a single operating system kernel typically has a long history. For example, most UNIX family history can be traced back to the 1960s. The most class operating system has a relatively old design and implementation (for example, a lot of the 1970s, 1980s, some UNIX code in there). In addition, often in terms of performance is slightly better than the same applications used in other operating system kernel structure (but generally considers that such advantages cannot be entirely due to the performance of a single core structure).

General and specialized, embedded

For general-purpose operating system is not operating system specific application requirements. Since there are no specific application requirements, the general-purpose operating system in order to meet a wider range of applications, the need to support more hardware and software needed for all of the user experience, the system is updated. The general-purpose operating system is a project the amount of heavy operating system.

Real-time and non-real-time

"Instant Operating System" (Real Time OS) refers to all resources, according to a certain scheduling and real-time communications capabilities of the operating system. But in the operating system theory "instant" refers to the time limit is usually specific operations consume (and space) it is predictable. For example, if an operating system provides real-time memory allocation operation, that is to say, a memory allocation operation takes time (and space) in any case will not exceed the upper limit of the operating system promises. Instant is very important in some areas, such as industrial control, medical equipment, video audio synthesis, as well as in the military field, are no instant or missing features.

Popular instant operating system QNX, VxWorks, RTLinux, etc., and Linux, most UNIX, Windows, and the majority of family members belong to the non-real-time operating system. A real-time operating system as a whole is usually immediate ability to rely on the kernel, but sometimes can be established on a non-real-time operating system real-time kernel, a lot of the Windows operating system to establish real-time category.

There is a secondary school in the POSIX standard specification system for real-time operating system API, including POSIX.4, POSIX.4a, POSIX.4b (collectively POSIX.4) and POSIX.13 like. Accord POSIX.4 operating system is generally recognized as the real-time operating system (real-time operating system, but does not need to meet the POSIX.4 standard).

8, 16, 32, 64, 128

The so-called 8, 16, 32, 64, 128, etc. The term sometimes refers to the width of the bus, sometimes referred to as an instruction width (in fixed-length instruction set), while in the operating system mainly refers to the theory of memory addressing width. If the width of the memory addressing is 16 bits, then each memory address can be used 16 binary bits to represent, that can be addressed in the range of 64KB. Similarly, 32 corresponding to the width of the 4GB addressing range, 64-bit addressing range corresponding to the width of 16 Exabyte. Memory addressing range is not just in terms of operating system and software design other types of sometimes being addressed range impact. However, in the design and implementation of the operating system, the addressable range but it has a more important significance.

In the early 16-bit operating system, the addressable range of 64KB is too small, most have adopted the "segment" plus "linear address" in the address space of two-dimensional design. The allocation of memory is often required to consider the question "segment substitution", while the application can use the address space also tend to have a relatively small limit.

In the 32-bit operating system, 4GB of an addressable range is more than enough for general applications, which typically use a one-dimensional linear address space, instead of using "segment."
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