Microsoft Corporation is an American multinational technology company with headquarters in Redmond, Washington. It develops, licenses and sells computer software, consumer electronics, personal computers, related services, its best known software products are the Microsoft Windows line of operating systems, the Microsoft Office suite, the Internet Explorer and Edge web browsers. Its flagship hardware products are the Xbox video game consoles and the Microsoft Surface lineup of touchscreen personal computers; as of 2016, it is the world's largest software maker by revenue, one of the world's most valuable companies. The word "Microsoft" is a portmanteau of "microcomputer" and "software". Microsoft is ranked No. 30 in the 2018 Fortune 500 rankings of the largest United States corporations by total revenue. Microsoft was founded by Bill Gates and Paul Allen on April 4, 1975, to develop and sell BASIC interpreters for the Altair 8800, it rose to dominate the personal computer operating system market with MS-DOS in the mid-1980s, followed by Microsoft Windows.
The company's 1986 initial public offering, subsequent rise in its share price, created three billionaires and an estimated 12,000 millionaires among Microsoft employees. Since the 1990s, it has diversified from the operating system market and has made a number of corporate acquisitions, their largest being the acquisition of LinkedIn for $26.2 billion in December 2016, followed by their acquisition of Skype Technologies for $8.5 billion in May 2011. As of 2015, Microsoft is market-dominant in the IBM PC-compatible operating system market and the office software suite market, although it has lost the majority of the overall operating system market to Android; the company produces a wide range of other consumer and enterprise software for desktops and servers, including Internet search, the digital services market, mixed reality, cloud computing and software development. Steve Ballmer replaced Gates as CEO in 2000, envisioned a "devices and services" strategy; this began with the acquisition of Danger Inc. in 2008, entering the personal computer production market for the first time in June 2012 with the launch of the Microsoft Surface line of tablet computers.
Since Satya Nadella took over as CEO in 2014, the company has scaled back on hardware and has instead focused on cloud computing, a move that helped the company's shares reach its highest value since December 1999. In 2018, Microsoft surpassed Apple as the most valuable publicly traded company in the world after being dethroned by the tech giant in 2010. Childhood friends Bill Gates and Paul Allen sought to make a business utilizing their shared skills in computer programming. In 1972 they founded their first company, named Traf-O-Data, which sold a rudimentary computer to track and analyze automobile traffic data. While Gates enrolled at Harvard, Allen pursued a degree in computer science at Washington State University, though he dropped out of school to work at Honeywell; the January 1975 issue of Popular Electronics featured Micro Instrumentation and Telemetry Systems's Altair 8800 microcomputer, which inspired Allen to suggest that they could program a BASIC interpreter for the device. After a call from Gates claiming to have a working interpreter, MITS requested a demonstration.
Since they didn't yet have one, Allen worked on a simulator for the Altair while Gates developed the interpreter. Although they developed the interpreter on a simulator and not the actual device, it worked flawlessly when they demonstrated the interpreter to MITS in Albuquerque, New Mexico. MITS agreed to distribute it, marketing it as Altair BASIC. Gates and Allen established Microsoft on April 4, 1975, with Gates as the CEO; the original name of "Micro-Soft" was suggested by Allen. In August 1977 the company formed an agreement with ASCII Magazine in Japan, resulting in its first international office, "ASCII Microsoft". Microsoft moved to a new home in Bellevue, Washington in January 1979. Microsoft entered the operating system business in 1980 with its own version of Unix, called Xenix. However, it was MS-DOS. After negotiations with Digital Research failed, IBM awarded a contract to Microsoft in November 1980 to provide a version of the CP/M OS, set to be used in the upcoming IBM Personal Computer.
For this deal, Microsoft purchased a CP/M clone called 86-DOS from Seattle Computer Products, which it branded as MS-DOS, though IBM rebranded it to PC DOS. Following the release of the IBM PC in August 1981, Microsoft retained ownership of MS-DOS. Since IBM had copyrighted the IBM PC BIOS, other companies had to reverse engineer it in order for non-IBM hardware to run as IBM PC compatibles, but no such restriction applied to the operating systems. Due to various factors, such as MS-DOS's available software selection, Microsoft became the leading PC operating systems vendor; the company expanded into new markets with the release of the Microsoft Mouse in 1983, as well as with a publishing division named Microsoft Press. Paul Allen resigned from Microsoft in 1983 after developing Hodgkin's disease. Allen claimed that Gates wanted to dilute his share in the company when he was diagnosed with Hodgkin's disease because he didn't think he was working hard enough. After leaving Microsoft, Allen lost billions of dollars on ill-conceived or mistimed technology investments.
He invested in low-tech sectors, sports teams, commercial real estate. Despite having begun jointly developing a new operating system, OS/2, with IBM in
O'Reilly is a group of families all of Irish Gaelic origin, who were the kings of East Bréifne in what is today County Cavan. The clan were part of the Connachta's Uí Briúin Bréifne kindred and were related to the Ó Ruairc of West Bréifne. O'Reilly is ranked tenth in the top twenty list of Irish surnames, it is the patronymic form of the Irish name Reilly. It is found throughout Ireland, with the greatest concentration of the surname found in County Cavan followed by Longford, Westmeath and Monaghan, the Province of Leinster, it is anglicised as Reilly, Riley and O'Reilly. The original form of the name, Ó Raghallaigh, denotes "from/of Raghallach", the name Raghallach thought to be derived from the compounds ragh and ceallach; the Ó Raghallaigh family were part of the Connachta, with the eponymous Raghallach said to have died at the Battle of Clontarf in 1014. The family became the kings of East Breifne, modern-day County County Longford; the name is common and widespread throughout Ireland, ranked 8th most common in 1890 and 11th in 1996.
The O'Reilly Clan Chieftain to this day is at odds with the O'Rourke Clan Chieftain because both clans viciously contest each other for the title Prince of Breifne. This was settled in 1994 when the Chief Herald of Ireland made the O'Rourke Chief the Prince of Breifne, but the Office of the Chief Herald stopped granting courtesy titles to Gaelic Chiefs in 2003. In 2017, with the election of the new O'Reilly Chief, the rivalry has been rekindled. People with the surname O'Reilly include: Alejandro O'Reilly, second Spanish governor of colonial Louisiana Andreas O'Reilly, Irish-born Austrian general Bernard O'Reilly, located the wreck of a Stinson aircraft in the McPherson Range, Australia, 1937 Bernard O'Reilly, Roman Catholic bishop Bernard O'Reilly, Roman Catholic bishop Bill O'Reilly, American commentator and television show host of The O'Reilly Factor on the Fox News Channel Bill O'Reilly, Australian cricketer Bob O'Reilly, Australian rugby league footballer Caitriona O'Reilly and critic Cal O'Reilly, Canadian ice hockey player Cameron O'Reilly and Australian businessman Cassia O'Reilly, Irish singer-songwriter Charles O'Reilly, Roman Catholic Bishop of Kilmore from 1798 to 1800.
Danny O'Reilly, Lead singer of Irish band, The Coronas David O'Reilly, several people includingDavid O'Reilly, film director and artist David J. O'Reilly, Chairman and CEO of Chevron CorporationDermot O'Reilly and songwriter in band Ryan's Fancy, contributed to the Music of Newfoundland and Labrador. Des O'Reilly, Australian rugby league player Emily O'Reilly, Irish journalist Emma O'Reilly, Irish physiotherapist and cycling soigneur and sued by Lance Armstrong. Finbarr O'Reilly, Canadian photographer Gary O'Reilly, English footballer Genevieve O'Reilly, Irish actress Heather O'Reilly, American soccer player Hugh Reily, Irish M. P. and political author James Reilly, Canadian businessman and politician from Alberta James O'Reilly, American Roman Catholic priest John Reyly was an M. P. for Cavan County in the Parliament of Ireland of 1689, known as the Patriot Parliament. John O'Reilly, Leader of The Saint Patrick's Battalion of Mexico John O'Reilly, Canadian politician from Ontario Joseph O'Reilly, Irish politician Kyle O'Reilly, ring name of Canadian professional wrestler Kyle Greenwood Leonora O'Reilly, an American feminist Luke O'Reilly Mary Margaret O'Reilly, Assistant Director of the United States Bureau of the Mint from 1924 to 1938 Margaret M. O'Reilly, Irish-born, American art curator, New Jersey State Museum Matthew O'Reilly, Irish politician and farmer Peter O'Reilly and official in the Colony of British Columbia Peter O'Reilly, Irish hurler Philip O'Reilly, M.
P. for County Cavan Philip Og O'Reilly was an M. P. for Cavan Borough in the Parliament of Ireland of 1689, known as the Patriot Parliament. Philip Reyley was an M. P. for Cavan County in the Parliament of Ireland of 1689, known as the Patriot Parliament. Randall C. O'Reilly, professor of psychology, developer of Leabra Robert O'Reilly, American actor Ruth O'Reilly, Irish rugby union player Ryan O'Reilly, Canadian ice hockey player Ryan O'Reilly, American professional wrestler Samuel O'Reilly, American inventor Stephen O'Reilly, American musician Stephen O'Reilly, American actor Stephen O'Reilly, Australian footballer Terry O'Reilly, hockey player Tom O'Reilly, Irish Fianna Fáil politician Tim O'Reilly, founder of O'Reilly Media Tom O'Reilly, Irish Gaelic footballer and politician Tom O'Reilly Irish Sinn Féin politician Tom O'Reilly, Papua New Guinea international Tony O'Reilly, Irish businessman Valli O'Reilly, Makeup artist Walter Cresswell O'Reilly, Australian Commonwealth Film Censor and founding President of the National Trust of Australia O'Reilly Lords of Bréifne c.1161–1607 Christopher O'Riley, American classical pianist and public radio show host Don O'Riley, Major League Baseball pitcher Bunny Wailer, reggae musician sometimes known as Bunny O'Riley Jon Riley, U
A path, the general form of the name of a file or directory, specifies a unique location in a file system. A path points to a file system location by following the directory tree hierarchy expressed in a string of characters in which path components, separated by a delimiting character, represent each directory; the delimiting character is most the slash, the backslash character, or colon, though some operating systems may use a different delimiter. Paths are used extensively in computer science to represent the directory/file relationships common in modern operating systems, are essential in the construction of Uniform Resource Locators. Resources can be represented by either relative paths. Multics first introduced a hierarchical file system with directories in the mid-1960s. Around 1970, Unix introduced the slash character as its directory separator. In 1981, the first version of Microsoft DOS was released. MS-DOS 1.0 did not support file directories. A major portion of the utility commands packaged with MS-DOS 1.0 came from IBM and their command line syntax used the slash character as a'switch' prefix.
For example, dir /w runs the'dir' command with the wide list format option. This use of slash can still be found in the command interface under Windows. By contrast, Unix uses the dash character as a command line switch prefix; when directory support was added to MS-DOS in version 2.0, "/" was kept as the switch prefix character for backwards compatibility. Microsoft chose the backslash character as a directory separator, which looks similar to the slash character. An absolute or full path points to the same location in a file system, regardless of the current working directory. To do that, it must include the root directory. By contrast, a relative path starts from some given working directory, avoiding the need to provide the full absolute path. A filename can be considered as a relative path based at the current working directory. If the working directory is not the file's parent directory, a file not found error will result if the file is addressed by its name. Japanese and Korean versions of Windows may display the'¥' character or the'₩' character instead of the directory separator.
In such cases the code for a backslash is being drawn as these characters. Early versions of MS-DOS replaced the backslash with these glyphs on the display to make it possible to display them by programs that only understood 7-bit ASCII. Although the first version of Windows supported the 8-bit ISO-8859-1 character set which has the Yen sign at U+00A5, modern versions of Windows supports Unicode which has the Won sign at U+20A9, much software will continue to display backslashes found in ASCII files this way to preserve backwards compatibility. Mac OS X, as a derivative of UNIX, uses UNIX paths internally. However, to preserve compatibility for software and familiarity for users, many portions of the GUI switch "/" typed by the user to ":" internally, switch them back when displaying filenames. Programming languages use paths. E.g.: When a file is opened. Most programming languages use the path representation of the underlying operating system: uxFile = fopen winFile = fopen This direct access to the operating system paths can hinder the portability of programs.
To support portable programs Java uses File.separator to distinguish between / and \ separated paths. Seed7 has a different approach for the path representation. In Seed7 all paths use independent of the operating system. Under windows a mapping takes place; the Microsoft Windows UNC, short for Universal Naming Convention or Uniform Naming Convention, specifies a common syntax to describe the location of a network resource, such as a shared file, directory, or printer. The UNC syntax for Windows systems has the generic form: \\ComputerName\SharedFolder\Resource Microsoft refers to this as a "network path"; some Microsoft Windows interfaces allow or require UNC syntax for WebDAV share access, rather than a URL. The UNC syntax is extended with optional components to denote use of SSL and TCP/IP port number, a WebDAV URL of http://HostName/SharedFolder/Resource becomes \\HostName\SharedFolder\Resource When viewed remotely, the "SharedFolder" may have a name different from what a program on the server sees when opening "\SharedFolder".
Instead, the SharedFolder name consists of an arbitrary name assigned to the folder when defining its "sharing". Some Microsoft Windows interfaces accept the "Long UNC": \\?\UNC\ComputerName\SharedFolder\Resource Microsoft Windows uses the following types of paths: local file system, such as C:\File uniform naming convention, such as \\Server\Volume\File or /<internet resource name> long UNC or UNCW, such as \\?\C:\File or \\?\UNC\Server\Volume\FileIn versions of Windows prior to Windows XP, only the APIs that accept "Long UNC" could accept more than 260 characters. The shell in Windows XP and Windows Vista, explorer.exe, allows path names up to 248 characters long. Since UNCs start with two backslashes, the backslash is used for string escaping and in regular expressions, this can result in extreme cases of leaning toothpick syndrome: an escaped string for a regular expression matching a UNC begins with 8 backslashes – \\\\\\\\ – because the string and regular expression both require escaping.
A command-line interface or command language interpreter known as command-line user interface, console user interface and character user interface, is a means of interacting with a computer program where the user issues commands to the program in the form of successive lines of text. A program which handles the interface is called shell; the CLI was the primary means of interaction with most computer systems on computer terminals in the mid-1960s, continued to be used throughout the 1970s and 1980s on OpenVMS, Unix systems and personal computer systems including MS-DOS, CP/M and Apple DOS. The interface is implemented with a command line shell, a program that accepts commands as text input and converts commands into appropriate operating system functions. Today, many end users if use command-line interfaces and instead rely upon graphical user interfaces and menu-driven interactions. However, many software developers, system administrators and advanced users still rely on command-line interfaces to perform tasks more efficiently, configure their machine, or access programs and program features that are not available through a graphical interface.
Alternatives to the command line include, but are not limited to text user interface menus, keyboard shortcuts, various other desktop metaphors centered on the pointer. Examples of this include the Windows versions 1, 2, 3, 3.1, 3.11, DosShell, Mouse Systems PowerPanel. Programs with command-line interfaces are easier to automate via scripting. Command-line interfaces for software other than operating systems include a number of programming languages such as Tcl/Tk, PHP, others, as well as utilities such as the compression utility WinZip, some FTP and SSH/Telnet clients. Compared with a graphical user interface, a command line requires fewer system resources to implement. Since options to commands are given in a few characters in each command line, an experienced user finds the options easier to access. Automation of repetitive tasks is simplified - most operating systems using a command line interface support some mechanism for storing used sequences in a disk file, for re-use. A command-line history can be kept, allowing repetition of commands.
A command-line system may require paper or online manuals for the user's reference, although a "help" option provides a concise review of the options of a command. The command-line environment may not provide the graphical enhancements such as different fonts or extended edit windows found in a GUI, it may be difficult for a new user to become familiar with all the commands and options available, compared with the drop-down menus of a graphical user interface, without repeated reference to manuals. Operating system command line interfaces are distinct programs supplied with the operating system. A program that implements such a text interface is called a command-line interpreter, command processor or shell. Examples of command-line interpreters include DEC's DIGITAL Command Language in OpenVMS and RSX-11, the various Unix shells, CP/M's CCP, DOS's COMMAND. COM, as well as the OS/2 and the Windows CMD. EXE programs, the latter groups being based on DEC's RSX-11 and RSTS CLIs. Under most operating systems, it is possible to replace the default shell program with alternatives.
Although the term'shell' is used to describe a command-line interpreter speaking a'shell' can be any program that constitutes the user-interface, including graphically oriented ones. For example, the default Windows GUI is a shell program named EXPLORER. EXE, as defined in the SHELL=EXPLORER. EXE line in the WIN. INI configuration file; these programs are shells, but not CLIs. Application programs may have command line interfaces. An application program may support none, any, or all of these three major types of command line interface mechanisms: Parameters: Most operating systems support a means to pass additional information to a program when it is launched; when a program is launched from an OS command line shell, additional text provided along with the program name is passed to the launched program. Interactive command line sessions: After launch, a program may provide an operator with an independent means to enter commands in the form of text. OS inter-process communication: Most operating systems support means of inter-process communication.
Command lines from client processes may be redirected to a CLI program by one of these methods. Some applications support only a CLI, presenting a CLI prompt to the user and acting upon command lines as they are entered. Other programs support both a CLI and a GUI. In some cases, a GUI is a wrapper around a separate CLI executable file. In other cases, a program may provide a CLI as an optional alternative to its GUI. CLIs and GUIs support different functionality. For example, all features of MATLAB, a numerical analysis computer program, are available via the CLI, whereas the MATLAB GUI exposes only a subset of features; the early Sierra games, such as the first three King's Quest games, used commands from an internal command line to move the character around in the graphic window. The command-line interface evolved from a form of dialog once conducted by humans over teleprinter machines, in which human operators remotely exchanged inf
In computing, Winlogon is the component of Microsoft Windows operating systems, responsible for handling the secure attention sequence, loading the user profile on logon, optionally locking the computer when a screensaver is running. The actual obtainment and verification of user credentials is left to other components. Winlogon is a common target for several threats that could modify its memory usage. Increased memory usage for this process might indicate that it has been "hijacked". In Windows Vista and operating systems, Winlogon's roles and responsibilities have changed significantly. Winlogon handles interface functions, it creates the desktops for the window station, implements time-out operations, in versions of Windows prior to Windows Vista, provides a set of support functions for the GINA and takes responsibility for configuring machine and user Group Policy. Winlogon checks if the copy of Windows is a legitimate license in Windows XP and versions. Winlogon has the following responsibilities: Window station and desktop protectionWinlogon sets the protection of the window station and corresponding desktops to ensure that each is properly accessible.
In general, this means that the local system will have full access to these objects and that an interactively logged-on user will have read access to the window station object and full access to the application desktop object. Standard SAS recognitionWinlogon has special hooks into the User32 server that allow it to monitor Control-Alt-Delete secure attention sequence events. Winlogon makes this SAS event information available to GINAs to use as their SAS, or as part of their SAS. In general, GINAs should monitor SASs on their own. SAS routine dispatchingWhen Winlogon encounters a SAS event or when a SAS is delivered to Winlogon by the GINA, Winlogon sets the state accordingly, changes to the Winlogon desktop, calls one of the SAS processing functions of the GINA. User profile loadingWhen users log on, their user profiles are loaded into the registry. In this way, the processes of the user can use the special registry key HKEY_CURRENT_USER. Winlogon does this automatically after a successful logon but before activation of the shell for the newly logged-on user.
Assignment of security to user shellWhen a user logs on, the GINA is responsible for creating one or more initial processes for that user. Winlogon provides a support function for the GINA to apply the security of the newly logged-on user to these processes. However, the preferred way to do this is for the GINA to call the Windows function CreateProcessAsUser, let the system provide the service. Screen saver controlWinlogon monitors keyboard and mouse activity to determine when to activate screen savers. After the screen saver is activated, Winlogon continues to monitor keyboard and mouse activity to determine when to terminate the screen saver. If the screen saver is marked as secure, Winlogon treats the workstation as locked; when there is mouse or keyboard activity, Winlogon invokes the WlxDisplayLockedNotice function of the GINA and locked workstation behavior resumes. If the screen saver is not secure, any keyboard or mouse activity terminates the screen saver without notification to the GINA.
Multiple network provider supportMultiple networks installed on a Windows system can be included in the authentication process and in password-updating operations. This inclusion lets additional networks gather identification and authentication information all at once during normal logon, using the secure desktop of Winlogon; some of the parameters required in the Winlogon services available to GINAs explicitly support these additional network providers. List of Microsoft Windows components Architecture of the Windows NT operating system line Vundo, a trojan that attaches itself to winlogon.exe getty, a similar process in UNIX Customizing GINA - Part 1, Developer tutorial for writing a custom GINA Customizing GINA - Part 2, Developer tutorial for writing a custom GINA MSKB:193361 MSGINA. DLL does not Reset WINLOGON Structure Windows Vista and Windows Server 2008: Understanding and Extending Security End-to-end — Microsoft PowerPoint presentation that includes information on changes to Winlogon in Windows Vista and Windows Server 2008
Microsoft Windows is a group of several graphical operating system families, all of which are developed and sold by Microsoft. Each family caters to a certain sector of the computing industry. Active Windows families include Windows Embedded. Defunct Windows families include Windows Mobile and Windows Phone. Microsoft introduced an operating environment named Windows on November 20, 1985, as a graphical operating system shell for MS-DOS in response to the growing interest in graphical user interfaces. Microsoft Windows came to dominate the world's personal computer market with over 90% market share, overtaking Mac OS, introduced in 1984. Apple came to see Windows as an unfair encroachment on their innovation in GUI development as implemented on products such as the Lisa and Macintosh. On PCs, Windows is still the most popular operating system. However, in 2014, Microsoft admitted losing the majority of the overall operating system market to Android, because of the massive growth in sales of Android smartphones.
In 2014, the number of Windows devices sold was less than 25 %. This comparison however may not be relevant, as the two operating systems traditionally target different platforms. Still, numbers for server use of Windows show one third market share, similar to that for end user use; as of October 2018, the most recent version of Windows for PCs, tablets and embedded devices is Windows 10. The most recent versions for server computers is Windows Server 2019. A specialized version of Windows runs on the Xbox One video game console. Microsoft, the developer of Windows, has registered several trademarks, each of which denote a family of Windows operating systems that target a specific sector of the computing industry; as of 2014, the following Windows families are being developed: Windows NT: Started as a family of operating systems with Windows NT 3.1, an operating system for server computers and workstations. It now consists of three operating system subfamilies that are released at the same time and share the same kernel: Windows: The operating system for mainstream personal computers and smartphones.
The latest version is Windows 10. The main competitor of this family is macOS by Apple for personal computers and Android for mobile devices. Windows Server: The operating system for server computers; the latest version is Windows Server 2019. Unlike its client sibling, it has adopted a strong naming scheme; the main competitor of this family is Linux. Windows PE: A lightweight version of its Windows sibling, meant to operate as a live operating system, used for installing Windows on bare-metal computers, recovery or troubleshooting purposes; the latest version is Windows PE 10. Windows IoT: Initially, Microsoft developed Windows CE as a general-purpose operating system for every device, too resource-limited to be called a full-fledged computer. However, Windows CE was renamed Windows Embedded Compact and was folded under Windows Compact trademark which consists of Windows Embedded Industry, Windows Embedded Professional, Windows Embedded Standard, Windows Embedded Handheld and Windows Embedded Automotive.
The following Windows families are no longer being developed: Windows 9x: An operating system that targeted consumers market. Discontinued because of suboptimal performance. Microsoft now caters to the consumer market with Windows NT. Windows Mobile: The predecessor to Windows Phone, it was a mobile phone operating system; the first version was called Pocket PC 2000. The last version is Windows Mobile 6.5. Windows Phone: An operating system sold only to manufacturers of smartphones; the first version was Windows Phone 7, followed by Windows Phone 8, the last version Windows Phone 8.1. It was succeeded by Windows 10 Mobile; the term Windows collectively describes any or all of several generations of Microsoft operating system products. These products are categorized as follows: The history of Windows dates back to 1981, when Microsoft started work on a program called "Interface Manager", it was announced in November 1983 under the name "Windows", but Windows 1.0 was not released until November 1985.
Windows 1.0 was to achieved little popularity. Windows 1.0 is not a complete operating system. The shell of Windows 1.0 is a program known as the MS-DOS Executive. Components included Calculator, Cardfile, Clipboard viewer, Control Panel, Paint, Reversi and Write. Windows 1.0 does not allow overlapping windows. Instead all windows are tiled. Only modal dialog boxes may appear over other windows. Microsoft sold as included Windows Development libraries with the C development environment, which included numerous windows samples. Windows 2.0 was released in December 1987, was more popular than its predecessor. It features several improvements to the user memory management. Windows 2.03 changed the OS from tiled windows to overlapping windows. The result of this change led to Apple Computer filing a suit against Microsoft alleging infringement on Apple's copyrights. Windows 2.0
An operating system is system software that manages computer hardware and software resources and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is executed directly by the hardware and makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer – from cellular phones and video game consoles to web servers and supercomputers; the dominant desktop operating system is Microsoft Windows with a market share of around 82.74%. MacOS by Apple Inc. is in second place, the varieties of Linux are collectively in third place. In the mobile sector, use in 2017 is up to 70% of Google's Android and according to third quarter 2016 data, Android on smartphones is dominant with 87.5 percent and a growth rate 10.3 percent per year, followed by Apple's iOS with 12.1 percent and a per year decrease in market share of 5.2 percent, while other operating systems amount to just 0.3 percent.
Linux distributions are dominant in supercomputing sectors. Other specialized classes of operating systems, such as embedded and real-time systems, exist for many applications. A single-tasking system can only run one program at a time, while a multi-tasking operating system allows more than one program to be running in concurrency; this is achieved by time-sharing, where the available processor time is divided between multiple processes. These processes are each interrupted in time slices by a task-scheduling subsystem of the operating system. Multi-tasking may be characterized in co-operative types. In preemptive multitasking, the operating system slices the CPU time and dedicates a slot to each of the programs. Unix-like operating systems, such as Solaris and Linux—as well as non-Unix-like, such as AmigaOS—support preemptive multitasking. Cooperative multitasking is achieved by relying on each process to provide time to the other processes in a defined manner. 16-bit versions of Microsoft Windows used cooperative multi-tasking.
32-bit versions of both Windows NT and Win9x, used preemptive multi-tasking. Single-user operating systems have no facilities to distinguish users, but may allow multiple programs to run in tandem. A multi-user operating system extends the basic concept of multi-tasking with facilities that identify processes and resources, such as disk space, belonging to multiple users, the system permits multiple users to interact with the system at the same time. Time-sharing operating systems schedule tasks for efficient use of the system and may include accounting software for cost allocation of processor time, mass storage and other resources to multiple users. A distributed operating system manages a group of distinct computers and makes them appear to be a single computer; the development of networked computers that could be linked and communicate with each other gave rise to distributed computing. Distributed computations are carried out on more than one machine; when computers in a group work in cooperation, they form a distributed system.
In an OS, distributed and cloud computing context, templating refers to creating a single virtual machine image as a guest operating system saving it as a tool for multiple running virtual machines. The technique is used both in virtualization and cloud computing management, is common in large server warehouses. Embedded operating systems are designed to be used in embedded computer systems, they are designed to operate on small machines like PDAs with less autonomy. They are able to operate with a limited number of resources, they are compact and efficient by design. Windows CE and Minix 3 are some examples of embedded operating systems. A real-time operating system is an operating system that guarantees to process events or data by a specific moment in time. A real-time operating system may be single- or multi-tasking, but when multitasking, it uses specialized scheduling algorithms so that a deterministic nature of behavior is achieved. An event-driven system switches between tasks based on their priorities or external events while time-sharing operating systems switch tasks based on clock interrupts.
A library operating system is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with the application and configuration code to construct a unikernel: a specialized, single address space, machine image that can be deployed to cloud or embedded environments. Early computers were built to perform a series of single tasks, like a calculator. Basic operating system features were developed in the 1950s, such as resident monitor functions that could automatically run different programs in succession to speed up processing. Operating systems did not exist in their more complex forms until the early 1960s. Hardware features were added, that enabled use of runtime libraries and parallel processing; when personal computers became popular in the 1980s, operating systems were made for them similar in concept to those used on larger computers. In the 1940s, the earliest electronic digital systems had no operating systems.
Electronic systems of this time were programmed on rows of mechanical switches or by jumper wires on plug boards. These were special-purpose systems that, for example, generated ballistics tables for the military or controlled the pri