Which Of The Following Manages The Resources And Provides Common Services For Computer Programs?

Operating systems
Mutual features
Process direction Interrupts Memory direction File arrangement Device drivers Networking (TCP/IP, UDP) Security (Process/Memory protection) I/O

An operating organisation (Bone) is a collection of software that manages computer hardware resources and provides common services for figurer programs. The operating system is a vital component of the system software in a calculator organization. Application programs usually require an operating system to part.

Fourth dimension-sharing operating systems schedule tasks for efficient utilise of the system and may likewise include accounting for price resource allotment of processor time, mass storage, printing, and other resources.

For hardware functions such as input and output and memory allotment, the operating organisation acts as an intermediary between programs and the computer hardware, ^{[one] [2]} although the awarding code is usually executed directly by the hardware and volition frequently make a system call to an Bone role or be interrupted by it. Operating systems tin be plant on near any device that contains a computer—from cellular phones and video game consoles to supercomputers and web servers.

Examples of pop modern operating systems include Android, BSD, iOS, Linux, Mac Bone X, Microsoft Windows, ^[3] Windows Phone, and IBM z/Os. All these, except Windows and z/Bone, share roots in UNIX.

Contents

• 1 Types of operating systems
• two History
  • 2.1 Mainframes
  • 2.2 Microcomputers
• 3 Examples of operating systems
  • three.1 UNIX and UNIX-similar operating systems
    • 3.1.1 BSD and its descendants
      • 3.1.1.1 Os X
    • 3.1.2 Linux and GNU
      • 3.one.2.1 Google Chromium OS
  • 3.2 Microsoft Windows
  • 3.iii Other
• 4 Components
  • 4.1 Kernel
    • iv.i.1 Programme execution
    • iv.1.2 Interrupts
    • 4.1.three Modes
    • 4.1.four Memory direction
    • 4.ane.5 Virtual retention
    • 4.i.half dozen Multitasking
    • 4.1.7 Disk access and file systems
    • 4.1.eight Device drivers
  • 4.2 Networking
  • 4.three Security
  • 4.four User interface
    • 4.4.1 Graphical user interfaces
• 5 Existent-time operating systems
• 6 Operating organisation evolution as a hobby
• vii Diversity of operating systems and portability
• 8 See also
• nine References
• x Further reading
• 11 External links

Types of operating systems

Existent-fourth dimension

A real-time operating organization is a multitasking operating organization that aims at executing real-fourth dimension applications. Existent-time operating systems often apply specialized scheduling algorithms so that they tin accomplish a deterministic nature of behavior. The primary objective of real-time operating systems is their quick and predictable response to events. They have an outcome-driven or fourth dimension-sharing design and often aspects of both. An outcome-driven system switches between tasks based on their priorities or external events while fourth dimension-sharing operating systems switch tasks based on clock interrupts.

Multi-user

A multi-user operating arrangement allows multiple users to access a reckoner organization at the same time. Fourth dimension-sharing systems and Internet servers tin can be classified every bit multi-user systems as they enable multiple-user access to a calculator through the sharing of time. Unmarried-user operating systems have but ane user just may allow multiple programs to run at the same time.

Multi-tasking vs. single-tasking

A multi-tasking operating system allows more than than one program to be running at a time, from the point of view of man time scales. A single-tasking system has merely one running program. Multi-tasking tin be of two types: pre-emptive and co-operative. In pre-emptive multitasking, the operating organisation slices the CPU time and dedicates one slot to each of the programs. Unix-like operating systems such as Solaris and Linux support pre-emptive multitasking, as does AmigaOS. Cooperative multitasking is accomplished by relying on each process to give time to the other processes in a divers manner. xvi-bit versions of Microsoft Windows used cooperative multi-tasking. 32-bit versions of both Windows NT and Win9x, used pre-emptive multi-tasking. Mac Bone prior to Bone Ten used to support cooperative multitasking.

Distributed

A distributed operating system manages a group of contained computers and makes them appear to be a single computer. The development of networked computers that could exist linked and communicate with each other gave rising to distributed computing. Distributed computations are carried out on more than one motorcar. When computers in a grouping work in cooperation, they make a distributed arrangement.

Embedded

Embedded operating systems are designed to exist 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 express number of resources. They are very compact and extremely efficient by blueprint. Windows CE and Minix 3 are some examples of embedded operating systems.

History

Early computers were built to perform a series of single tasks, similar a calculator. Operating systems did not exist in their modernistic and more complex forms until the early 1960s. ^[4] Basic operating system features were adult in the 1950s, such as resident monitor functions that could automatically run dissimilar programs in succession to speed up processing. Hardware features were added that enabled use of runtime libraries, interrupts, 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 case, generated ballistics tables for the military or controlled the printing of payroll checks from data on punched paper cards. Later on programmable general purpose computers were invented, automobile languages (consisting of strings of the binary digits 0 and ane on punched newspaper tape) were introduced that sped upwards the programming process (Stern, 1981).

Os/360 was used on well-nigh IBM mainframe computers beginning in 1966, including the computers that helped NASA put a human being on the moon.

In the early 1950s, a reckoner could execute only ane program at a time. Each user had sole use of the estimator for a express period of time and would arrive at a scheduled time with programme and information on punched paper cards and/or punched tape. The program would be loaded into the auto, and the machine would be set to work until the programme completed or crashed. Programs could generally exist debugged via a front end panel using toggle switches and panel lights. Information technology is said that Alan Turing was a master of this on the early Manchester Mark 1 machine, and he was already deriving the primitive conception of an operating organisation from the principles of the Universal Turing machine. ^[four]

Later machines came with libraries of programs, which would be linked to a user'southward program to aid in operations such every bit input and output and generating computer code from human-readable symbolic code. This was the genesis of the modern-day operating organization. Notwithstanding, machines still ran a unmarried task at a time. At Cambridge University in England the job queue was at one time a washing line from which tapes were hung with different colored dress-pegs to bespeak job-priority.^{[ citation needed ]}

Mainframes

Through the 1950s, many major features were pioneered in the field of operating systems, including batch processing, input/output interrupt, buffering, multitasking, spooling, runtime libraries, link-loading, and programs for sorting records in files. These features were included or non included in application software at the option of awarding programmers, rather than in a separate operating arrangement used by all applications. In 1959 the SHARE Operating System was released as an integrated utility for the IBM 704, and later in the 709 and 7090 mainframes, although information technology was rapidly supplanted by IBSYS/IBJOB on the 709, 7090 and 7094.

During the 1960s, IBM's OS/360 introduced the concept of a single Bone spanning an entire product line, which was crucial for the success of the System/360 machines. IBM's current mainframe operating systems are distant descendants of this original organization and applications written for OS/360 can still be run on modern machines.^{[ citation needed ]}

OS/360 also pioneered the concept that the operating organization keeps rails of all of the system resources that are used, including plan and information space allocation in primary memory and file space in secondary storage, and file locking during update. When the process is terminated for whatsoever reason, all of these resources are re-claimed by the operating system.

The alternative CP-67 system for the S/360-67 started a whole line of IBM operating systems focused on the concept of virtual machines. Other operating systems used on IBM S/360 series mainframes included systems adult past IBM: COS/360 (Compatibility Operating System), DOS/360 (Disk Operating System), TSS/360 (Time Sharing System), TOS/360 (Tape Operating Organisation), BOS/360 (Basic Operating System), and ACP (Airline Command Program), likewise every bit a few non-IBM systems: MTS (Michigan Terminal Arrangement), MUSIC (Multi-User System for Interactive Computing), and ORVYL (Stanford Timesharing System).

Command Data Corporation developed the SCOPE operating organization in the 1960s, for batch processing. In cooperation with the University of Minnesota, the Kronos and later the NOS operating systems were developed during the 1970s, which supported simultaneous batch and timesharing employ. Like many commercial timesharing systems, its interface was an extension of the Dartmouth Bones operating systems, one of the pioneering efforts in timesharing and programming languages. In the late 1970s, Control Data and the University of Illinois developed the PLATO operating system, which used plasma panel displays and long-distance fourth dimension sharing networks. Plato was remarkably innovative for its time, featuring real-time chat, and multi-user graphical games. Burroughs Corporation introduced the B5000 in 1961 with the MCP, (Master Control Program) operating system. The B5000 was a stack machine designed to exclusively back up loftier-level languages with no motorcar language or assembler, and indeed the MCP was the commencement Bone to exist written exclusively in a high-level linguistic communication – ESPOL, a dialect of ALGOL. MCP also introduced many other ground-breaking innovations, such as beingness the first commercial implementation of virtual retentiveness. During evolution of the AS400, IBM made an approach to Burroughs to licence MCP to run on the AS400 hardware. This proposal was declined by Burroughs management to protect its existing hardware product. MCP is still in utilize today in the Unisys ClearPath/MCP line of computers.

UNIVAC, the kickoff commercial computer manufacturer, produced a series of EXEC operating systems. Like all early chief-frame systems, this was a batch-oriented organization that managed magnetic drums, disks, menu readers and line printers. In the 1970s, UNIVAC produced the Existent-Time Basic (RTB) arrangement to support large-scale time sharing, too patterned subsequently the Dartmouth BC system.

General Electric and MIT developed General Electric Comprehensive Operating Supervisor (GECOS), which introduced the concept of ringed security privilege levels. After acquisition past Honeywell it was renamed to General Comprehensive Operating Organisation (GCOS).

Digital Equipment Corporation developed many operating systems for its various calculator lines, including TOPS-10 and TOPS-twenty time sharing systems for the 36-bit PDP-10 class systems. Prior to the widespread employ of UNIX, TOPS-10 was a particularly pop system in universities, and in the early ARPANET community.

In the late 1960s through the late 1970s, several hardware capabilities evolved that allowed similar or ported software to run on more than than one system. Early systems had utilized microprogramming to implement features on their systems in order to permit different underlying computer architectures to announced to be the same every bit others in a series. In fact most 360s subsequently the 360/40 (except the 360/165 and 360/168) were microprogrammed implementations. But before long other means of achieving application compatibility were proven to be more significant.

The enormous investment in software for these systems made since 1960s caused about of the original computer manufacturers to continue to develop compatible operating systems along with the hardware. The notable supported mainframe operating systems include:

• Burroughs MCP – B5000, 1961 to Unisys Clearpath/MCP, present.
• IBM Os/360 – IBM System/360, 1966 to IBM z/Os, present.
• IBM CP-67 – IBM System/360, 1967 to IBM z/VM, present.
• UNIVAC EXEC 8 – UNIVAC 1108, 1967, to OS 2200 Unisys Clearpath Dorado, nowadays.

Microcomputers

PC-DOS was an early personal computer Bone that featured a command line interface.

The first microcomputers did not have the capacity or need for the elaborate operating systems that had been adult for mainframes and minis; minimalistic operating systems were developed, often loaded from ROM and known as monitors. One notable early disk operating arrangement was CP/Grand, which was supported on many early on microcomputers and was closely imitated by Microsoft'south MS-DOS, which became wildly popular as the operating arrangement chosen for the IBM PC (IBM's version of it was called IBM DOS or PC DOS). In the '80s, Apple tree Computer Inc. (now Apple tree Inc.) abandoned its popular Apple tree II series of microcomputers to introduce the Apple Macintosh computer with an innovative Graphical User Interface (GUI) to the Mac Os.

The introduction of the Intel 80386 CPU chip with 32-bit architecture and paging capabilities, provided personal computers with the ability to run multitasking operating systems like those of earlier minicomputers and mainframes. Microsoft responded to this progress by hiring Dave Cutler, who had adult the VMS operating organization for Digital Equipment Corporation. He would lead the evolution of the Windows NT operating organisation, which continues to serve as the footing for Microsoft's operating systems line. Steve Jobs, a co-founder of Apple Inc., started NeXT Computer Inc., which adult the NEXTSTEP operating system. NEXTSTEP would later be acquired by Apple Inc. and used, along with code from FreeBSD as the core of Mac Os X.

The GNU Project was started by activist and programmer Richard Stallman with the goal of creating a complete gratuitous software replacement to the proprietary UNIX operating system. While the projection was highly successful in duplicating the functionality of various parts of UNIX, development of the GNU Hurd kernel proved to be unproductive. In 1991, Finnish information science educatee Linus Torvalds, with cooperation from volunteers collaborating over the Cyberspace, released the first version of the Linux kernel. It was before long merged with the GNU user space components and system software to class a consummate operating system. Since then, the combination of the two major components has usually been referred to as only "Linux" past the software industry, a naming convention that Stallman and the Free Software Foundation remain opposed to, preferring the name GNU/Linux. The Berkeley Software Distribution, known equally BSD, is the UNIX derivative distributed by the Academy of California, Berkeley, starting in the 1970s. Freely distributed and ported to many minicomputers, information technology eventually too gained a following for use on PCs, mainly as FreeBSD, NetBSD and OpenBSD.

Examples of operating systems

UNIX and UNIX-like operating systems

Evolution of Unix systems

Main article: Unix

Unix was originally written in assembly language. ^[5] Ken Thompson wrote B, mainly based on BCPL, based on his experience in the MULTICS projection. B was replaced by C, and Unix, rewritten in C, developed into a large, complex family of inter-related operating systems which accept been influential in every modern operating system (see History).

The UNIX-like family is a diverse grouping of operating systems, with several major sub-categories including System V, BSD, and Linux. The name "UNIX" is a trademark of The Open up Grouping which licenses it for use with whatever operating system that has been shown to conform to their definitions. "UNIX-like" is commonly used to refer to the large set of operating systems which resemble the original UNIX.

Unix-like systems run on a wide variety of computer architectures. They are used heavily for servers in business, as well as workstations in academic and engineering environments. Free UNIX variants, such as Linux and BSD, are popular in these areas.

Four operating systems are certified by the The Open Grouping (holder of the Unix trademark) equally Unix. HP'south HP-UX and IBM's AIX are both descendants of the original Organisation V Unix and are designed to run simply on their respective vendor'southward hardware. In contrast, Sun Microsystems's Solaris Operating System can run on multiple types of hardware, including x86 and Sparc servers, and PCs. Apple'due south OS X, a replacement for Apple's earlier (non-Unix) Mac OS, is a hybrid kernel-based BSD variant derived from NeXTSTEP, Mach, and FreeBSD.

Unix interoperability was sought by establishing the POSIX standard. The POSIX standard can be applied to whatsoever operating arrangement, although it was originally created for diverse Unix variants.

BSD and its descendants

A subgroup of the Unix family is the Berkeley Software Distribution family unit, which includes FreeBSD, NetBSD, and OpenBSD. These operating systems are most commonly found on webservers, although they can also function as a personal figurer Os. The Internet owes much of its existence to BSD, as many of the protocols at present commonly used by computers to connect, send and receive data over a network were widely implemented and refined in BSD. The www was also first demonstrated on a number of computers running an OS based on BSD chosen NextStep.

BSD has its roots in Unix. In 1974, University of California, Berkeley installed its first Unix system. Over time, students and staff in the estimator scientific discipline department there began adding new programs to brand things easier, such equally text editors. When Berkely received new VAX computers in 1978 with Unix installed, the school's undergraduates modified Unix even more in social club to have advantage of the computer'southward hardware possibilities. The Defense Advanced Enquiry Projects Agency of the US Department of Defense took interest, and decided to fund the project. Many schools, corporations, and government organizations took find and started to use Berkeley'southward version of Unix instead of the official one distributed by AT&T.

Steve Jobs, upon leaving Apple Inc. in 1985, formed NeXT Inc., a company that manufactured loftier-terminate computers running on a variation of BSD chosen NeXTSTEP. One of these computers was used by Tim Berners-Lee equally the commencement webserver to create the World Wide Web.

Developers similar Keith Bostic encouraged the project to replace whatsoever non-free lawmaking that originated with Bell Labs. Once this was done, yet, AT&T sued. Eventually, afterwards two years of legal disputes, the BSD project came out ahead and spawned a number of free derivatives, such as FreeBSD and NetBSD.

Bone X

Primary article: Os X

The standard user interface of Os X

OS X (formerly "Mac Bone X") is a line of open cadre graphical operating systems developed, marketed, and sold by Apple tree Inc., the latest of which is pre-loaded on all currently aircraft Macintosh computers. Os X is the successor to the original Mac Bone, which had been Apple's chief operating system since 1984. Unlike its predecessor, OS X is a UNIX operating organization built on technology that had been developed at Adjacent through the second half of the 1980s and upward until Apple tree purchased the company in early 1997. The operating arrangement was first released in 1999 as Mac Os 10 Server 1.0, with a desktop-oriented version (Mac Os X v10.0 "Cheetah") post-obit in March 2001. Since then, six more singled-out "client" and "server" editions of OS X have been released, the near recent existence OS X x.8 "Mountain Lion", which was first made available on Feb 16, 2012 for developers, and was so released to the public on July 25, 2012. Releases of OS X are named after large cats.

Prior to its merging with OS X, the server edition – Os X Server – was architecturally identical to its desktop counterpart and usually ran on Apple's line of Macintosh server hardware. OS X Server included piece of work group management and administration software tools that provide simplified admission to central network services, including a post transfer agent, a Samba server, an LDAP server, a domain proper name server, and others. With Mac Bone X v10.7 Panthera leo, all server aspects of Mac OS X Server accept been integrated into the client version and the product re-branded every bit "Bone X" (dropping "Mac" from the name). The server tools are now offered equally an application. ^[6]

Linux and GNU

Chief articles: GNU, Linux, and Linux kernel

Android, a popular mobile operating arrangement using the Linux kernel

Linux (or GNU/Linux) is a Unix-like operating organisation that was developed without any actual Unix code, different BSD and its variants. Linux can exist used on a broad range of devices from supercomputers to wristwatches. The Linux kernel is released under an open source license, then anyone tin can read and change its code. It has been modified to run on a large variety of electronics. Although estimates suggest that Linux is used on 1.82% of all personal computers, ^{[7] [viii]} it has been widely adopted for use in servers ^[ix] and embedded systems ^[10] (such as cell phones). Linux has superseded Unix in most places^{[ which? ]}, and is used on the 10 most powerful supercomputers in the world. ^[11] The Linux kernel is used in some pop distributions, such equally Cherry-red Hat, Debian, Ubuntu, Linux Mint and Google's Android.

The GNU project is a mass collaboration of programmers who seek to create a completely free and open operating system that was similar to Unix but with completely original code. It was started in 1983 by Richard Stallman, and is responsible for many of the parts of most Linux variants. Thousands of pieces of software for nigh every operating system are licensed under the GNU General Public License. Meanwhile, the Linux kernel began as a side project of Linus Torvalds, a university student from Finland. In 1991, Torvalds began work on information technology, and posted information nigh his projection on a newsgroup for reckoner students and programmers. He received a wave of support and volunteers who ended upward creating a full-fledged kernel. Programmers from GNU took find, and members of both projects worked to integrate the finished GNU parts with the Linux kernel in society to create a total-fledged operating system.

Google Chromium OS

Chromium is an operating organization based on the Linux kernel and designed by Google. Since Chromium Os targets estimator users who spend virtually of their time on the Net, it is mainly a web browser with limited ability to run local applications, though it has a built-in file manager and media player. Instead, information technology relies on Net applications (or Web apps) used in the web browser to accomplish tasks such every bit word processing, as well equally online storage for storing nigh files.^{[ citation needed ]}

Microsoft Windows

Microsoft Windows is a family of proprietary operating systems designed past Microsoft Corporation and primarily targeted to Intel architecture based computers, with an estimated 88.9 percent total usage share on Spider web connected computers. ^{[8] [12] [thirteen] [xiv]} The newest version is Windows 8 for workstations and Windows Server 2012 for servers. Windows seven recently overtook Windows XP as near used OS. ^{[15] [16] [17]}

Microsoft Windows originated in 1985 as an operating environment running on meridian of MS-DOS, which was the standard operating arrangement shipped on most Intel architecture personal computers at the time. In 1995, Windows 95 was released which only used MS-DOS every bit a bootstrap. For backwards compatibility, Win9x could run real-manner MS-DOS ^{[18] [19]} and xvi $.25 Windows iii.x ^[20] drivers. Windows ME, released in 2000, was the final version in the Win9x family. Afterward versions have all been based on the Windows NT kernel. Electric current versions of Windows run on IA-32 and x86-64 microprocessors, although Windows 8 will support ARM architecture. In the by, Windows NT supported non-Intel architectures.

Server editions of Windows are widely used. In recent years, Microsoft has expended pregnant capital letter in an effort to promote the utilise of Windows as a server operating system. However, Windows' usage on servers is not every bit widespread as on personal computers, as Windows competes against Linux and BSD for server market share. ^{[21] [22]}

Other

In that location have been many operating systems that were pregnant in their mean solar day but are no longer then, such equally AmigaOS; OS/two from IBM and Microsoft; Mac Os, the non-Unix precursor to Apple's Mac OS X; BeOS; XTS-300; RISC OS; MorphOS and FreeMint. Some are withal used in niche markets and keep to be developed every bit minority platforms for enthusiast communities and specialist applications. OpenVMS formerly from December, is however under active development past Hewlett-Packard. Yet other operating systems are used almost exclusively in academia, for operating systems education or to do inquiry on operating system concepts. A typical example of a system that fulfills both roles is MINIX, while for case Singularity is used purely for inquiry.

Other operating systems have failed to win significant market share, but accept introduced innovations that accept influenced mainstream operating systems, non least Bell Labs' Program 9.

Components

The components of an operating system all exist in order to make the different parts of a figurer piece of work together. All user software needs to get through the operating system in order to use any of the hardware, whether information technology be as simple as a mouse or keyboard or as complex every bit an Internet component.

Kernel

A kernel connects the application software to the hardware of a computer.

With the aid of the firmware and device drivers, the kernel provides the about basic level of control over all of the computer'southward hardware devices. It manages memory access for programs in the RAM, it determines which programs get access to which hardware resources, it sets upward or resets the CPU'southward operating states for optimal functioning at all times, and it organizes the data for long-term not-volatile storage with file systems on such media as disks, tapes, flash retention, etc.

Program execution

The operating organization provides an interface betwixt an application program and the calculator hardware, so that an application program tin can interact with the hardware just by obeying rules and procedures programmed into the operating system. The operating system is also a set up of services which simplify development and execution of application programs. Executing an application program involves the creation of a process by the operating system kernel which assigns memory space and other resources, establishes a priority for the procedure in multi-tasking systems, loads program binary code into retentivity, and initiates execution of the application program which and so interacts with the user and with hardware devices.

Interrupts

Interrupts are central to operating systems, every bit they provide an efficient manner for the operating arrangement to interact with and react to its environment. The alternative — having the operating system "watch" the diverse sources of input for events (polling) that require activeness — tin exist found in older systems with very minor stacks (50 or 60 bytes) but are unusual in modern systems with big stacks. Interrupt-based programming is directly supported by well-nigh mod CPUs. Interrupts provide a computer with a way of automatically saving local annals contexts, and running specific code in response to events. Fifty-fifty very bones computers back up hardware interrupts, and allow the programmer to specify lawmaking which may exist run when that event takes place.

When an interrupt is received, the reckoner's hardware automatically suspends whatever program is currently running, saves its status, and runs calculator lawmaking previously associated with the interrupt; this is analogous to placing a bookmark in a book in response to a telephone phone call. In modernistic operating systems, interrupts are handled past the operating organization's kernel. Interrupts may come from either the computer's hardware or from the running program.

When a hardware device triggers an interrupt, the operating system'due south kernel decides how to bargain with this consequence, more often than not by running some processing code. The amount of code beingness run depends on the priority of the interrupt (for example: a person normally responds to a fume detector alarm before answering the phone). The processing of hardware interrupts is a task that is usually delegated to software chosen device driver, which may exist either part of the operating organisation's kernel, role of another plan, or both. Device drivers may then relay information to a running plan by various means.

A program may also trigger an interrupt to the operating system. If a plan wishes to admission hardware for example, it may interrupt the operating system'southward kernel, which causes control to exist passed back to the kernel. The kernel will then process the request. If a program wishes boosted resource (or wishes to shed resource) such as memory, it will trigger an interrupt to get the kernel's attention.

Modes

Privilege rings for the x86 available in protected mode. Operating systems make up one's mind which processes run in each mode.

Modern CPUs support multiple modes of operation. CPUs with this capability use at least 2 modes: protected fashion and supervisor mode. The supervisor way is used past the operating arrangement's kernel for low level tasks that demand unrestricted admission to hardware, such every bit controlling how memory is written and erased, and communication with devices like graphics cards. Protected mode, in contrast, is used for almost everything else. Applications operate within protected mode, and tin can merely utilise hardware past communicating with the kernel, which controls everything in supervisor manner. CPUs might have other modes similar to protected mode besides, such as the virtual modes in order to emulate older processor types, such as 16-scrap processors on a 32-bit one, or 32-chip processors on a 64-fleck i.

When a computer first starts up, information technology is automatically running in supervisor manner. The first few programs to run on the computer, existence the BIOS or EFI, bootloader, and the operating arrangement have unlimited access to hardware – and this is required because, by definition, initializing a protected environment tin can simply be done outside of one. Nonetheless, when the operating organisation passes control to another program, it can place the CPU into protected mode.

In protected mode, programs may have access to a more limited ready of the CPU's instructions. A user program may get out protected fashion only past triggering an interrupt, causing command to be passed back to the kernel. In this manner the operating system tin can maintain exclusive control over things like admission to hardware and memory.

The term "protected mode resource" mostly refers to one or more CPU registers, which contain information that the running program isn't allowed to alter. Attempts to alter these resources generally causes a switch to supervisor mode, where the operating arrangement tin can deal with the illegal operation the program was attempting (for instance, by killing the programme).

Retentiveness direction

Among other things, a multiprogramming operating system kernel must be responsible for managing all system memory which is currently in utilise by programs. This ensures that a program does not interfere with memory already in use by another programme. Since programs time share, each program must have contained access to memory.

Cooperative retention management, used past many early operating systems, assumes that all programs brand voluntary utilise of the kernel's retentiveness director, and practise not exceed their allocated memory. This arrangement of retention management is almost never seen any more, since programs often contain bugs which tin can cause them to exceed their allocated retention. If a plan fails, it may cause memory used by ane or more other programs to be affected or overwritten. Malicious programs or viruses may purposefully alter some other programme'southward memory, or may affect the operation of the operating system itself. With cooperative memory management, it takes only one misbehaved programme to crash the system.

Memory protection enables the kernel to limit a process' access to the calculator's memory. Various methods of memory protection be, including retention division and paging. All methods require some level of hardware back up (such as the 80286 MMU), which doesn't exist in all computers.

In both segmentation and paging, certain protected mode registers specify to the CPU what memory address it should permit a running program to access. Attempts to access other addresses volition trigger an interrupt which will crusade the CPU to re-enter supervisor mode, placing the kernel in charge. This is called a segmentation violation or Seg-V for short, and since it is both hard to assign a meaningful effect to such an operation, and considering information technology is ordinarily a sign of a misbehaving plan, the kernel will generally resort to terminating the offending plan, and volition report the error.

Windows 3.1-Me had some level of retentiveness protection, simply programs could easily circumvent the need to use it. A general protection fault would be produced, indicating a division violation had occurred; however, the system would often crash anyway.

Virtual retentivity

Main article: Virtual memory

Many operating systems can "trick" programs into using memory scattered effectually the hard disk drive and RAM as if information technology is one continuous chunk of memory, chosen virtual retention.

The use of virtual memory addressing (such as paging or partition) means that the kernel tin choose what memory each program may utilize at any given time, allowing the operating system to use the same memory locations for multiple tasks.

If a program tries to access memory that isn't in its current range of attainable memory, only nevertheless has been allocated to it, the kernel will be interrupted in the same way equally it would if the programme were to exceed its allocated retentiveness. (Run into section on memory management.) Under UNIX this kind of interrupt is referred to as a page mistake.

When the kernel detects a page error it will more often than not accommodate the virtual memory range of the plan which triggered it, granting it access to the retentiveness requested. This gives the kernel discretionary power over where a particular application's retentivity is stored, or fifty-fifty whether or not it has really been allocated yet.

In modernistic operating systems, retentiveness which is accessed less oft can exist temporarily stored on disk or other media to make that space available for employ by other programs. This is chosen swapping, as an area of memory can be used by multiple programs, and what that memory area contains tin can be swapped or exchanged on demand.

"Virtual retentiveness" provides the programmer or the user with the perception that in that location is a much larger amount of RAM in the computer than is really there. ^[23]

Multitasking

Multitasking refers to the running of multiple contained computer programs on the aforementioned computer; giving the appearance that information technology is performing the tasks at the same time. Since most computers tin do at most i or two things at one time, this is mostly done via fourth dimension-sharing, which ways that each programme uses a share of the estimator'due south time to execute.

An operating arrangement kernel contains a piece of software called a scheduler which determines how much time each program will spend executing, and in which social club execution control should be passed to programs. Control is passed to a process by the kernel, which allows the program admission to the CPU and retentivity. Later on, control is returned to the kernel through some mechanism, so that some other program may be allowed to use the CPU. This so-called passing of control betwixt the kernel and applications is chosen a context switch.

An early model which governed the allocation of time to programs was called cooperative multitasking. In this model, when control is passed to a program by the kernel, it may execute for as long as information technology wants earlier explicitly returning command to the kernel. This ways that a malicious or malfunctioning programme may not simply prevent whatever other programs from using the CPU, merely it tin can hang the unabridged organisation if it enters an space loop.

Modern operating systems extend the concepts of application preemption to device drivers and kernel code, then that the operating system has preemptive control over internal run-times as well.

The philosophy governing preemptive multitasking is that of ensuring that all programs are given regular fourth dimension on the CPU. This implies that all programs must be express in how much time they are allowed to spend on the CPU without existence interrupted. To reach this, modernistic operating system kernels make use of a timed interrupt. A protected manner timer is ready by the kernel which triggers a return to supervisor fashion after the specified fourth dimension has elapsed. (See above sections on Interrupts and Dual Style Operation.)

On many single user operating systems cooperative multitasking is perfectly adequate, as dwelling computers more often than not run a modest number of well tested programs. The AmigaOS is an exception, having pre-emptive multitasking from its very first version. Windows NT was the first version of Microsoft Windows which enforced preemptive multitasking, only it didn't achieve the domicile user market until Windows XP (since Windows NT was targeted at professionals).

Disk admission and file systems

Filesystems let users and programs to organize and sort files on a calculator, often through the use of directories (or "folders")

Access to data stored on disks is a central feature of all operating systems. Computers store data on disks using files, which are structured in specific means in order to permit for faster access, college reliability, and to make better use out of the bulldoze's bachelor infinite. The specific fashion in which files are stored on a deejay is called a file system, and enables files to take names and attributes. It also allows them to be stored in a hierarchy of directories or folders bundled in a directory tree.

Early operating systems generally supported a unmarried type of disk drive and only one kind of file system. Early file systems were limited in their capacity, speed, and in the kinds of file names and directory structures they could use. These limitations often reflected limitations in the operating systems they were designed for, making information technology very difficult for an operating organisation to support more than than one file organization.

While many simpler operating systems support a limited range of options for accessing storage systems, operating systems like UNIX and Linux back up a engineering known as a virtual file system or VFS. An operating system such equally UNIX supports a wide array of storage devices, regardless of their pattern or file systems, allowing them to be accessed through a common application programming interface (API). This makes information technology unnecessary for programs to take any noesis about the device they are accessing. A VFS allows the operating system to provide programs with admission to an unlimited number of devices with an infinite variety of file systems installed on them, through the utilise of specific device drivers and file system drivers.

A connected storage device, such equally a difficult bulldoze, is accessed through a device commuter. The device driver understands the specific language of the drive and is able to translate that language into a standard linguistic communication used by the operating organisation to access all disk drives. On UNIX, this is the language of block devices.

When the kernel has an appropriate device driver in identify, it can then access the contents of the deejay drive in raw format, which may contain one or more file systems. A file system driver is used to translate the commands used to access each specific file system into a standard prepare of commands that the operating system tin employ to talk to all file systems. Programs tin can and so deal with these file systems on the basis of filenames, and directories/folders, contained within a hierarchical construction. They can create, delete, open up, and close files, besides equally gather various information about them, including access permissions, size, gratis infinite, and cosmos and modification dates.

Various differences between file systems make supporting all file systems difficult. Allowed characters in file names, instance sensitivity, and the presence of various kinds of file attributes makes the implementation of a unmarried interface for every file system a daunting task. Operating systems tend to recommend using (then back up natively) file systems specifically designed for them; for example, NTFS in Windows and ext3 and ReiserFS in Linux. However, in practice, third party drives are usually available to give back up for the almost widely used file systems in most full general-purpose operating systems (for example, NTFS is bachelor in Linux through NTFS-3g, and ext2/3 and ReiserFS are bachelor in Windows through tertiary-party software).

Support for file systems is highly varied among mod operating systems, although there are several mutual file systems which nearly all operating systems include support and drivers for. Operating systems vary on file system back up and on the disk formats they may be installed on. Nether Windows, each file system is usually express in application to certain media; for instance, CDs must use ISO 9660 or UDF, and as of Windows Vista, NTFS is the only file organization which the operating organization tin can be installed on. It is possible to install Linux onto many types of file systems. Unlike other operating systems, Linux and UNIX allow whatever file system to exist used regardless of the media information technology is stored in, whether information technology is a hard drive, a disc (CD,DVD...), a USB wink drive, or fifty-fifty contained within a file located on some other file system.

Device drivers

Primary commodity: Device driver

A device commuter is a specific type of computer software adult to allow interaction with hardware devices. Typically this constitutes an interface for communicating with the device, through the specific estimator bus or communications subsystem that the hardware is connected to, providing commands to and/or receiving data from the device, and on the other terminate, the requisite interfaces to the operating system and software applications. It is a specialized hardware-dependent computer plan which is also operating organization specific that enables some other programme, typically an operating system or applications software package or computer program running nether the operating organisation kernel, to interact transparently with a hardware device, and usually provides the requisite interrupt handling necessary for any necessary asynchronous time-dependent hardware interfacing needs.

The key blueprint goal of device drivers is abstraction. Every model of hardware (fifty-fifty inside the aforementioned form of device) is different. Newer models likewise are released by manufacturers that provide more reliable or better performance and these newer models are often controlled differently. Computers and their operating systems cannot be expected to know how to control every device, both now and in the future. To solve this trouble, operating systems substantially dictate how every type of device should exist controlled. The function of the device driver is then to interpret these operating organization mandated function calls into device specific calls. In theory a new device, which is controlled in a new style, should role correctly if a suitable commuter is available. This new driver volition ensure that the device appears to operate as usual from the operating organisation's point of view.

Under versions of Windows before Vista and versions of Linux before 2.vi, all commuter execution was branch, meaning that if a driver entered an infinite loop it would freeze the system. More recent revisions of these operating systems incorporate kernel preemption, where the kernel interrupts the commuter to requite it tasks, and so separates itself from the process until it receives a response from the device driver, or gives it more tasks to do.

Networking

Currently most operating systems support a diversity of networking protocols, hardware, and applications for using them. This means that computers running different operating systems tin participate in a common network for sharing resources such as computing, files, printers, and scanners using either wired or wireless connections. Networks can essentially allow a estimator's operating system to access the resources of a remote computer to support the same functions as information technology could if those resources were connected straight to the local computer. This includes everything from uncomplicated communication, to using networked file systems or fifty-fifty sharing another reckoner's graphics or sound hardware. Some network services let the resources of a computer to be accessed transparently, such as SSH which allows networked users straight access to a computer'due south control line interface.

Customer/server networking allows a program on a computer, called a customer, to connect via a network to another computer, called a server. Servers offer (or host) various services to other network computers and users. These services are usually provided through ports or numbered access points beyond the server's network address. Each port number is usually associated with a maximum of one running plan, which is responsible for handling requests to that port. A daemon, being a user programme, can in plough access the local hardware resource of that computer by passing requests to the operating organization kernel.

Many operating systems back up 1 or more vendor-specific or open networking protocols equally well, for example, SNA on IBM systems, DECnet on systems from Digital Equipment Corporation, and Microsoft-specific protocols (SMB) on Windows. Specific protocols for specific tasks may also be supported such every bit NFS for file access. Protocols like ESound, or esd can be hands extended over the network to provide sound from local applications, on a remote organisation's sound hardware.

Security

A reckoner being secure depends on a number of technologies working properly. A modern operating system provides access to a number of resource, which are available to software running on the system, and to external devices like networks via the kernel.

The operating organization must exist capable of distinguishing between requests which should be allowed to be processed, and others which should non exist processed. While some systems may merely distinguish betwixt "privileged" and "non-privileged", systems usually have a class of requester identity, such as a user name. To plant identity there may be a procedure of authentication. Often a username must be quoted, and each username may have a password. Other methods of authentication, such as magnetic cards or biometric data, might exist used instead. In some cases, especially connections from the network, resources may be accessed with no authentication at all (such as reading files over a network share). As well covered by the concept of requester identity is dominance; the particular services and resources attainable by the requester in one case logged into a system are tied to either the requester'due south user account or to the variously configured groups of users to which the requester belongs.

In addition to the let/disallow model of security, a system with a high level of security will too offering auditing options. These would allow tracking of requests for access to resources (such as, "who has been reading this file?"). Internal security, or security from an already running plan is but possible if all possibly harmful requests must be carried out through interrupts to the operating organization kernel. If programs tin directly access hardware and resources, they cannot exist secured.

External security involves a request from outside the calculator, such as a login at a connected console or some kind of network connection. External requests are ofttimes passed through device drivers to the operating organisation's kernel, where they can exist passed onto applications, or carried out direct. Security of operating systems has long been a business organization considering of highly sensitive data held on computers, both of a commercial and military nature. The United States Authorities Department of Defense (DoD) created the Trusted Computer Organisation Evaluation Criteria (TCSEC) which is a standard that sets basic requirements for assessing the effectiveness of security. This became of vital importance to operating organisation makers, because the TCSEC was used to evaluate, allocate and select trusted operating systems being considered for the processing, storage and retrieval of sensitive or classified information.

Network services include offerings such equally file sharing, print services, electronic mail, spider web sites, and file transfer protocols (FTP), well-nigh of which can take compromised security. At the forepart line of security are hardware devices known as firewalls or intrusion detection/prevention systems. At the operating organization level, at that place are a number of software firewalls available, equally well as intrusion detection/prevention systems. Most mod operating systems include a software firewall, which is enabled by default. A software firewall tin can be configured to allow or deny network traffic to or from a service or awarding running on the operating system. Therefore, one can install and be running an insecure service, such every bit Telnet or FTP, and not have to be threatened past a security breach because the firewall would deny all traffic trying to connect to the service on that port.

An alternative strategy, and the merely sandbox strategy available in systems that practise not meet the Popek and Goldberg virtualization requirements, is the operating system not running user programs equally native code, but instead either emulates a processor or provides a host for a p-code based system such equally Java.

Internal security is especially relevant for multi-user systems; it allows each user of the organisation to have individual files that the other users cannot tamper with or read. Internal security is also vital if auditing is to be of any use, since a program can potentially featherbed the operating system, inclusive of bypassing auditing.

User interface

A screenshot of the Bourne Again Shell command line. Each command is typed out afterwards the 'prompt', and then its output appears below, working its way downwardly the screen. The current control prompt is at the bottom.

Every reckoner that is to be operated past an individual requires a user interface. The user interface is usually referred to as a shell and is essential if human interaction is to be supported. The user interface views the directory structure and requests services from the operating organisation that will larn data from input hardware devices, such as a keyboard, mouse or credit carte reader, and requests operating system services to display prompts, status messages and such on output hardware devices, such every bit a video monitor or printer. The two most mutual forms of a user interface take historically been the command-line interface, where computer commands are typed out line-by-line, and the graphical user interface, where a visual environs (most commonly a WIMP) is present.

Graphical user interfaces

A screenshot of the KDE Plasma Desktop graphical user interface. Programs take the form of images on the screen, and the files, folders (directories), and applications take the form of icons and symbols. A mouse is used to navigate the computer.

About of the modern computer systems support graphical user interfaces (GUI), and ofttimes include them. In some computer systems, such equally the original implementation of Mac Os, the GUI is integrated into the kernel.

While technically a graphical user interface is non an operating organization service, incorporating support for ane into the operating system kernel tin can permit the GUI to be more responsive by reducing the number of context switches required for the GUI to perform its output functions. Other operating systems are modular, separating the graphics subsystem from the kernel and the Operating System. In the 1980s UNIX, VMS and many others had operating systems that were built this way. Linux and Mac Os Ten are too built this manner. Modern releases of Microsoft Windows such every bit Windows Vista implement a graphics subsystem that is mostly in user-infinite; withal the graphics cartoon routines of versions between Windows NT 4.0 and Windows Server 2003 exist mostly in kernel space. Windows 9x had very piffling distinction between the interface and the kernel.

Many computer operating systems allow the user to install or create any user interface they desire. The Ten Window System in conjunction with GNOME or KDE Plasma Desktop is a unremarkably found setup on nigh Unix and Unix-like (BSD, Linux, Solaris) systems. A number of Windows shell replacements have been released for Microsoft Windows, which offer alternatives to the included Windows shell, but the shell itself cannot be separated from Windows.

Numerous Unix-based GUIs have existed over time, most derived from X11. Competition amongst the diverse vendors of Unix (HP, IBM, Sunday) led to much fragmentation, though an effort to standardize in the 1990s to COSE and CDE failed for various reasons, and were eventually eclipsed by the widespread adoption of GNOME and Thou Desktop Surround. Prior to gratuitous software-based toolkits and desktop environments, Motif was the prevalent toolkit/desktop combination (and was the basis upon which CDE was developed).

Graphical user interfaces evolve over time. For instance, Windows has modified its user interface nearly every fourth dimension a new major version of Windows is released, and the Mac OS GUI changed dramatically with the introduction of Mac Os X in 1999. ^[24]

Real-fourth dimension operating systems

A real-time operating organisation (RTOS) is a multitasking operating system intended for applications with fixed deadlines (existent-fourth dimension computing). Such applications include some small embedded systems, automobile engine controllers, industrial robots, spacecraft, industrial control, and some big-scale calculating systems.

An early case of a large-scale existent-time operating system was Transaction Processing Facility developed by American Airlines and IBM for the Sabre Airline Reservations System.

Embedded systems that accept stock-still deadlines employ a real-time operating organisation such equally VxWorks, PikeOS, eCos, QNX, MontaVista Linux and RTLinux. Windows CE is a existent-time operating system that shares similar APIs to desktop Windows merely shares none of desktop Windows' codebase.^{[ citation needed ]} Symbian OS also has an RTOS kernel (EKA2) starting with version 8.0b.

Some embedded systems use operating systems such every bit Palm Bone, BSD, and Linux, although such operating systems do non support real-time computing.

Operating organization development every bit a hobby

Operating organization evolution is one of the well-nigh complicated activities in which a computing hobbyist may engage. A hobby operating system may be classified every bit one whose code has not been directly derived from an existing operating system, and has few users and active developers. ^[25]

In some cases, hobby development is in back up of a "homebrew" calculating device, for example, a simple unmarried-board computer powered by a 6502 microprocessor. Or, development may be for an compages already in widespread use. Operating system development may come up from entirely new concepts, or may commence past modeling an existing operating system. In either case, the hobbyist is his/her ain developer, or may interact with a small and sometimes unstructured group of individuals who have similar interests.

Examples of a hobby operating arrangement include ReactOS and Syllable.

Diversity of operating systems and portability

Application software is generally written for use on a specific operating system, and sometimes even for specific hardware. When porting the application to run on another Os, the functionality required by that awarding may be implemented differently by that OS (the names of functions, meaning of arguments, etc.) requiring the awarding to be adapted, changed, or otherwise maintained.

This cost in supporting operating systems diversity tin can exist avoided by instead writing applications confronting software platforms like Java or Qt. These abstractions have already borne the toll of adaptation to specific operating systems and their organisation libraries.

Another approach is for operating system vendors to adopt standards. For case, POSIX and OS abstraction layers provide commonalities that reduce porting costs.

Meet also

Perbandingan -- operating systems Handheld computers Hypervisor Interruptible operating system Daftar/Tabel -- important publications in operating systems Daftar/Tabel -- operating systems Microcontroller

Network operating system Object-oriented operating system Operating System Projects PCjacking System image Timeline of operating systems Usage share of operating systems

References

1. ^ Stallings (2005). Operating Systems, Internals and Design Principles. Pearson: Prentice Hall. p. 6.
2. ^ Dhotre, I.A. (2009). Operating Systems.. Technical Publications. p. 1.
3. ^ "Operating Organisation Market place Share". Internet Applications. http://marketshare.hitslink.com/operating-system-market-share.aspx?qprid=x.
4. ^ ^{a b} Hansen, Per Brinch, ed. (2001). Classic Operating Systems. Springer. pp. 4–7. ISBN 0-387-95113-X. http://books.google.com/?id=-PDPBvIPYBkC&lpg=PP1&pg=PP1#5=onepage&q.
5. ^ Ritchie, Dennis. "Unix Manual, offset edition". Lucent Technologies. http://cm.bell-labs.com/cm/cs/who/dmr/1stEdman.html . Retrieved 22 November 2012.
6. ^ "Bone 10 Mountain King of beasts – Move your Mac even further ahead". Apple. http://world wide web.apple.com/macosx/lion/ . Retrieved 2012-08-07.
7. ^ Usage share of operating systems
8. ^ ^{a b} "Summit five Operating Systems from Jan to April 2011". StatCounter. October 2009. http://gs.statcounter.com/#os-ww-monthly-201101-201104-bar . Retrieved November 5, 2009.
9. ^ "IDC report into Server market place share". Idc.com. http://world wide web.idc.com/about/viewpressrelease.jsp?containerId=prUS22360110&sectionId=null&elementId=goose egg&pageType=SYNOPSIS . Retrieved 2012-08-07.
10. ^ Linux still tiptop embedded OS
11. ^ Jermoluk, Tom (2012-08-03). "TOP500 Listing – November 2010 (1–100) | TOP500 Supercomputing Sites". Top500.org. http://www.top500.org/list/2010/11/100 . Retrieved 2012-08-07.
12. ^ "Global Web Stats". Internet Market place Share, Net Applications. May 2011. http://marketshare.hitslink.com/operating-system-market-share.aspx?qprid=viii . Retrieved 2011-05-07.
13. ^ "Global Web Stats". W3Counter, Awio Web Services. September 2009. http://world wide web.w3counter.com/globalstats.php . Retrieved 2009-10-24.
14. ^ "Operating Organization Marketplace Share". Internet Applications. Oct 2009. http://marketshare.hitslink.com/operating-organisation-market-share.aspx?qprid=eight . Retrieved Nov 5, 2009.
15. ^ "w3schools.com OS Platform Statistics". http://www.w3schools.com/browsers/browsers_os.asp . Retrieved October xxx, 2011.
16. ^ "Stats Count Global Stats Top V Operating Systems". http://gs.statcounter.com/#os-ww-monthly-201010-201110 . Retrieved October xxx, 2011.
17. ^ "Global statistics at w3counter.com". http://www.w3counter.com/globalstats.php . Retrieved 23 January 2012.
18. ^ "Troubleshooting MS-DOS Compatibility Fashion on Hard Disks". Back up.microsoft.com. http://back up.microsoft.com/kb/130179/EN-US . Retrieved 2012-08-07.
19. ^ "Using NDIS two PCMCIA Network Card Drivers in Windows 95". Support.microsoft.com. http://back up.microsoft.com/kb/134748/en . Retrieved 2012-08-07.
20. ^ "INFO: Windows 95 Multimedia Wave Device Drivers Must be 16 bit". Support.microsoft.com. http://support.microsoft.com/kb/163354/en . Retrieved 2012-08-07.
21. ^ "Operating Organisation Share past Groups for Sites in All Locations January 2009". http://news.netcraft.com/SSL-Survey/CMatch/osdv_all.
22. ^ "Behind the IDC data: Windows still No. i in server operating systems". ZDNet. 2010-02-26. http://blogs.zdnet.com/microsoft/?p=5408.
23. ^ Stallings, William (2008). Computer System & Architecture. New Delhi: Prentice-Hall of India Individual Limited. p. 267. ISBN 978-81-203-2962-ane.
24. ^ Poisson, Ken. "Chronology of Personal Computer Software". Retrieved on 2008-05-07. Last checked on 2009-03-thirty.
25. ^ "My Os is less hobby than yours". Osnews. December 21, 2009. http://world wide web.osnews.com/story/22638/My_OS_Is_Less_Hobby_than_Yours . Retrieved December 21, 2009.

Farther reading

• Auslander, Marc A.; Larkin, David C.; Scherr, Allan L. (1981). The development of the MVS Operating System. IBM J. Enquiry & Development. http://www.inquiry.ibm.com/journal/rd/255/auslander.pdf.
• Deitel, Harvey K.; Deitel, Paul; Choffnes, David. Operating Systems. Pearson/Prentice Hall. ISBN 978-0-13-092641-viii.
• Bic, Lubomur F.; Shaw, Alan C. (2003). Operating Systems. Pearson: Prentice Hall.
• Silberschatz, Avi; Galvin, Peter; Gagne, Greg (2008). Operating Systems Concepts. John Wiley & Sons. ISBN 0-470-12872-0.

External links

• Operating Systems at the Open Directory Project
• Multics History and the history of operating systems
• How Stuff Works – Operating Systems
• Assistance finding your Operating Organization type and version

Operating system
General	Advancement Comparison History Hobbyist development Listing Timeline Usage share
Kernel	Architectures Exokernel Hybrid Microkernel Monolithic Components Device driver Loadable kernel module Microkernel User space
Process direction	Concepts Context switch Interrupt IPC Process Process control block Thread Scheduling algorithms Computer multitasking Fixed-priority preemptive Multilevel feedback queue Preemptive Round-robin Shortest job adjacent
Retentiveness management and resource protection	General protection fault Retentiveness protection Paging Security rings Segmentation fault / Omnibus error Virtual memory
Storage access and file systems	Boot loader Defragmentation Device file File attribute Inode Periodical Partition Virtual file system Virtual record library
List	AmigaOS Android BeOS BSD DOS GNU Linux Mac Bone MorphOS Os/2 ReactOS Solaris Unix Windows
Miscellaneous concepts	API Figurer network HAL Live CD Live USB Bone crush CLI GUI TUI VUI PXE

Systems and systems scientific discipline
Systems categories	Systems theory Systems science Systems scientists Conceptual Physical Social
Systems	Biological Complex Complex adaptive Conceptual Coupled human-surround arrangement Database management Dynamical Economical Ecosystem Formal Global Positioning Organisation Human anatomy Information systems Legal systems Systems of measurement Metric system Multi-agent system Nervous organization Nonlinearity Operating system Physical system Political system Sensory system Social arrangement Solar System Systems art
Theoretical fields	Chaos theory Complex systems Command theory Cybernetics Earth organization science Living systems Sociotechnical systems theory System dynamics Systems biology Systems ecology Systems engineering Systems neuroscience Systems psychology Systems science Systems theory World-systems theory
Systems scientists	Russell Ackoff William Ross Ashby Béla Bánáthy Gregory Bateson Stafford Beer Richard Bellman Ludwig von Bertalanffy Kenneth Boulding Murray Bowen West Churchman George Dantzig Heinz von Foerster Jay Wright Forrester Charles A S Hall George Klir Edward Lorenz Niklas Luhmann Humberto Maturana Margaret Mead Donella Meadows Mihajlo Mesarovic James Grier Miller Howard Odum Talcott Parsons Ilya Prigogine Anatol Rapoport Claude Shannon Qian Xuesen Francisco Varela Kevin Warwick Norbert Wiener Anthony Wilden

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