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Encyclopedia > Operating system

An operating system (OS) is a software that manages computer resources and provides programmers with an interface used to access those resources. An operating system processes system data and user input, and responds by allocating and managing tasks and internal system resources as a service to users and programs of the system. An operating system performs basic tasks such as controlling and allocating memory, prioritizing system requests, controlling input and output devices, facilitating computer networking and managing files. Operating systems can be found on almost anything made with integrated circuits, such as personal computers, internet servers, cellphones, music players, routers, switches, wireless access points, network storage, game consoles, digital cameras, sewing machines and telescopes. Software redirects here. ... This article is about the machine. ... Look up interface in Wiktionary, the free dictionary. ... 1 GiB of SDRAM mounted in a personal computer. ... Energy Input: The energy placed into a reaction. ... This article or section is in need of attention from an expert on the subject. ...


In most cases, the operating system is not the first code to run on the computer at startup (boot) time. The initial code executing on the computer is usually loaded from firmware, which is stored in Flash ROM. This is sometimes called the BIOS or boot ROM. The firmware loads and executes the operating system kernel (usually from disk, sometimes over the network), and is usually responsible for the first graphics or text output the user sees onscreen. A microcontroller, like this PIC18F8720 is controlled by firmware stored inside on FLASH memory In computing, firmware is a computer program that is embedded in a hardware device, for example a microcontroller. ... For other uses, see Bios. ... A kernel connects the application software to the hardware of a computer. ...


Common contemporary desktop OSes are Linux, Mac OS X, Microsoft Windows and Solaris. Windows is most popular on desktops while Linux is most popular in server environments. Linux, Mac OS X and MS Windows all have server and personal variants. With the exception of Microsoft Windows, the designs of each of the aforementioned OSs were inspired by, or directly inherited from, the Unix operating system. Unix was developed at Bell Labs beginning in the late 1960s and spawned the development of numerous free and proprietary operating systems. This article is about operating systems that use the Linux kernel. ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... 1. ... Solaris is a computer operating system developed by Sun Microsystems. ... Look up server in Wiktionary, the free dictionary. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ...


Many users equate the desktop environment with the underlying operating system[citation needed]. Information in this article or section has not been verified against sources and may not be reliable. ...

Contents

Underlying Technologies

An operating system is a collection of technologies which are designed to allow the computer to perform certain functions. These technologies may or may not be present in every operating system, and there are often differences in how they are implemented. However as stated above most modern operating systems are derived from common design ancestors, and are therefore basically similar.


Program Execution

Main article: Process (computing)

An operating system's most basic function is to support the running of programs by the users. On a multiprogramming operating system, running programs are commonly referred to as processes. Process management refers to the facilities provided by the operating system to support the creation, execution, and destruction of processes, and to facilitate various interactions, and limit others. In computing, a process is an instance of a computer program that is being executed. ... In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is... In computing, a process is an instance of a computer program that is being executed. ...


The operating system's kernel in conjunction with underlying hardware must support this functionality. A kernel connects the application software to the hardware of a computer. ...


Executing a program involves the creation of a process by the operating system. The kernel creates a process by setting aside or allocating some memory, loading program code from a disk or another part of memory into the newly allocated space, and starting it running. A kernel connects the application software to the hardware of a computer. ...


Operating system kernels store various information about running processes. This information might include: A kernel connects the application software to the hardware of a computer. ...

  • A unique identifier, called a process identifier (PID).
  • A list of memory the program is using, or is allowed to access.
  • The PID of the program which requested its execution, or the parent process ID (PPID).
  • The filename and/or path from which the program was loaded.
  • A register file, containing the last values of all CPU registers.
  • A program counter, indicating the position in the program.

Interrupts

Main article: interrupt

Interrupts are central to operating systems as they allow the operating system to deal with the unexpected activities of running programs and the world outside the computer. Interrupt-based programming is one of the most basic forms of time-sharing, being directly supported by most CPUs. Interrupts provide a computer with a way of automatically running specific code in response to events. Even very basic computers support hardware interrupts, and allow the programmer to specify code which may be run when that event takes place. In computing, an interrupt is an asynchronous signal from hardware or software indicating the need for attention. ... In computing, an interrupt is an asynchronous signal from hardware or software indicating the need for attention. ... In computing, an interrupt is an asynchronous signal from hardware or software indicating the need for attention. ...


When an interrupt is received, the computer's hardware automatically suspends whatever program is currently running, and its registers and program counter are saved. This is analogous to placing a bookmark in a book when someone is interrupted by a phone call. This task requires no operating system as such, but only that the interrupt be configured at an earlier time. Historically, a register was a sign or chalkboard onto which people would write cash transactions for later bookkeeping, often with chalk. ...


In modern operating systems, interrupts are handled by the operating system'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's kernel decides how to deal with this event, generally by running some processing code, or ignoring it. The processing of hardware interrupts is a task that is usually delegated to software called device drivers, which may be either part of the operating system's kernel, part of another program, or both. Device drivers may then relay information to a running program by various means. A kernel connects the application software to the hardware of a computer. ... A kernel connects the application software to the hardware of a computer. ... A kernel connects the application software to the hardware of a computer. ...


A program may also trigger an interrupt to the operating system, which are very similar in function. If a program wishes to access hardware for example, it may interrupt the operating system's kernel, which causes control to be passes back to the kernel. The kernel may then process the request which may contain instructions to be passed onto hardware, or to a device driver. When a program wishes to allocate more memory, launch or communicate with another program, or signal that it no longer needs the CPU, it does so through interrupts. A kernel connects the application software to the hardware of a computer. ... A kernel connects the application software to the hardware of a computer. ... A kernel connects the application software to the hardware of a computer. ...


Protected Mode, and Supervisor Mode Operation

Main article: Protected mode
Main article: Supervisor mode

Modern CPUs support something called dual mode operation. CPUs with this capability use two modes: protected mode and supervisor mode, which allow certain CPU functions to be controlled and affected only by the operating system kernel. Here, protected mode does not refer specifically to the 80286 CPU feature, although its general protected modes are generally very similar to it. CPUs might have other modes similar to 80286 protected mode as well, such as the virtual 8086 mode of the 80386. Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ... In computer terms, supervisor mode is a hardware-mediated flag which can be changed by code running in system-level software. ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ... Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ... In computer terms, supervisor mode is a hardware-mediated flag which can be changed by code running in system-level software. ... A kernel connects the application software to the hardware of a computer. ... The Intel 80286 is an x86-family 16-bit microprocessor that was introduced by Intel on February 1, 1982. ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ... In the 80386 and later, Virtual 8086 mode, also called virtual real mode (or VM86), allows the execution of real mode applications that violate the rules under the control of a protected mode operating system. ... The Intel 80386 is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 1994 and later. ...


However, the term is used here more generally in operating system theory to refer to all modes which limit the capabilities of programs running in that mode, providing things like virtual memory addressing and limiting access to hardware in a manner determined by a program running in supervisor mode. Similar modes have existed in supercomputers, minicomputers, and mainframes as they are essential to fully supporting UNIX-like multi-user operating systems.


When a computer first starts up, it is automatically running in supervisor mode. The first few programs to run on the computer, being the BIOS, bootloader and the operating system have unlimited access to hardware. However when the operating system passes control to another program, it can place the CPU into protected mode. For other uses, see Bios. ... In computing, booting is a bootstrapping process that starts operating systems when the user turns on a computer system. ... Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ...


In protected mode, programs may have access to a more limited set of the CPU's instructions. A user program may leave protected mode only by triggering an interrupt, causing control to be passed back to the kernel. In this way the operating system can maintain exclusive control over things like access to hardware, and memory. Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ... Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ... A kernel connects the application software to the hardware of a computer. ...


The term "protected mode resource" generally 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.


Memory Management

Main article: memory protection

Among other things, a multiprogramming operating system kernel must be responsible for managing all system memory which is currently in use by programs. This ensures that a program does not interfere with memory already used by another program. Since programs time share, each program must have independent access to memory. Memory protection is a system that prevents one process from corrupting the memory of another process running on the same computer at the same time. ... A kernel connects the application software to the hardware of a computer. ...


Cooperative memory management, used by many early operating systems assumes that all programs make voluntary use of the kernel's memory manager, and do not exceed their allocated memory. This system of memory management is almost never seen anymore, since programs often contain bugs which can cause them to exceed their allocated memory. If a program fails it may cause memory used by one or more other programs to be affected or overwritten. Malicious programs, or viruses may purposefully alter another program's memory or may affect the operation of the operating system itself. With cooperative memory management it takes only one misbehaved program to crash the system. A kernel connects the application software to the hardware of a computer. ...


Memory protection enables the kernel to limit a process' access to the computer's memory. Various methods of memory protection exist, including memory segmentation, and paging. All methods require some level of hardware support (such as the 80286 MMU) which doesn't exist in all computers. Memory protection is a system that prevents one process from corrupting the memory of another process running on the same computer at the same time. ... A kernel connects the application software to the hardware of a computer. ... Segmentation is one of the most common ways to achieve memory protection; another common one is paging. ... In computer operating systems, paging memory allocation, paging refers to the process of managing program access to virtual memory pages that do not currently reside in RAM. It is implemented as a task that resides in the kernel of the operating system and gains control when a page fault takes... The Intel 80286 is an x86-family 16-bit microprocessor that was introduced by Intel on February 1, 1982. ...


In both segmentation and paging, certain protected mode registers specify to the CPU what memory address it should allow a running program to access. Attempts to access other addresses will trigger an interrupt which will cause 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 usually a sign of a misbehaving program, the kernel will generally kill the offending program, and report the error. Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ... In computer terms, supervisor mode is a hardware-mediated flag which can be changed by code running in system-level software. ... A kernel connects the application software to the hardware of a computer. ... A segmentation fault (often shortened to segfault) is a particular error condition that can occur during the operation of computer software. ... A kernel connects the application software to the hardware of a computer. ...


Windows 3.1-Me had some level of memory protection, but programs could easily circumvent the need to use it. Under Windows 9x all MS-DOS applications ran in supervisor mode, giving them almost unlimited control over the computer. A general protection fault would be produced indicating a segmentation violation had occurred, however the system would often crash anyway. In computer terms, supervisor mode is a hardware-mediated flag which can be changed by code running in system-level software. ... A General Protection Fault (GPF) in the Intel x86 and AMD x86-64 architectures is a fault (a type of an interrupt) which can encompass several cases, where protection mechanisms within the processor architecture are violated by any of the programs that is running, whether it be the kernel or...


Methods of Multitasking

Main article: Computer multitasking
Main article: Process management (computing)

Multitasking refers to the running of multiple independent computer programs on the same computer, giving the appearance that it is performing the tasks at the same time. Since most computers can do at most one or two things at one time, this is generally done via time sharing, which means that each program uses a share of the computer's time to execute. In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is... Multitasking may refer to any of the following: Computer multitasking - the apparent simultaneous performance of two or more tasks by a computers central processing unit. ...


An operating system kernel contains a piece of software called a scheduler which determines how much time each program will spend executing, and in which order execution control should be passed to programs. Control is passed to a process by the kernel, which allows the program access the CPU and memory. At a later time control is returned to the kernel through some mechanism, so that another program may be allowed to user the CPU. The this so-called passing of control between the kernel and applications is called a context switch. A kernel connects the application software to the hardware of a computer. ... For disk scheduling, see I/O scheduling. ... A kernel connects the application software to the hardware of a computer. ... CPU redirects here. ... A kernel connects the application software to the hardware of a computer. ... A context switch is the computing process of storing and restoring the state (context) of a CPU such that multiple processes can share a single CPU resource. ...


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 it wants before explicitly returning control to the kernel. This means that a malfunctioning program may prevent any other programs from using the CPU. In computing, cooperative multitasking (or non-preemptive multitasking) is a form of multitasking in which multiple tasks execute by voluntarily ceding control to other tasks at programmer-defined points within each task. ... A kernel connects the application software to the hardware of a computer. ... A kernel connects the application software to the hardware of a computer. ...


The philosophy governing preemptive multitasking is that of ensuring that all programs are given regular time on the CPU. This implies that all programs must be limited in how much time they are allowed to spend on the CPU without being interrupted. To accomplish this, modern operating system kernels make use of a timed interrupt. A protected mode timer is set by the kernel which triggers a return to supervisor mode after the specified time has elapsed. (See above sections on Interrupts and Dual Mode Operation.) Pre-emptive multitasking is a form of multitasking in which processes are not allowed to take an indefinitely long time to complete execution in the CPU. Each process, in turn, is granted a portion of CPU time (usually called a time slice, on the order of milliseconds). ... Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ...


On many single user operating systems cooperative multitasking is perfectly adequate, as home computers generally run a small number of well tested programs. Windows XP Home Edition was the first version of Microsoft Windows for the home user market which included full preemptive multitasking capability, although it has always existed in Windows NT. UNIX which was originally designed with multiple users in mind has supported preemptive multitasking for decades when hardware permitted. A typical Windows XP desktop. ... Windows redirects here. ... Windows NT (New Technology) is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ...

Further information: Context switch
Further information: Preemptive multitasking
Further information: Cooperative multitasking

A context switch is the computing process of storing and restoring the state (context) of a CPU such that multiple processes can share a single CPU resource. ... Pre-emptive multitasking is a form of multitasking in which processes are not allowed to take an indefinitely long time to complete execution in the CPU. Each process, in turn, is granted a portion of CPU time (usually called a time slice, on the order of milliseconds). ... In computing, cooperative multitasking (or non-preemptive multitasking) is a form of multitasking in which multiple tasks execute by voluntarily ceding control to other tasks at programmer-defined points within each task. ...

Disk Access and File Systems

Main article: Virtual file system

Access to files stored on disks is a central feature of all operating systems. Computers store data on disks using files, which are structured in specific ways in order to allow for faster access, higher reliability, and to make better use out of the drive's available space. The specific way files are stored on a disk is called a file system, and enables files to have names, and attributes. It also allows them to be stored in a hierarchy of directories or folders arranged in a directory tree. A virtual file system (VFS) or virtual filesystem switch is an abstraction layer on top of a more concrete file system. ... A disk or disc may be: Look up disc, disk in Wiktionary, the free dictionary. ... File has several meanings: Computer file File (tool) file (Unix), a program used to determine file types. ... In computing, a directory, catalog, or folder[1] is an entity in a file system which contains a group of files and/or other directories. ...


Early operating systems generally supported a single type of disk drive and only one kind 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 it very difficult for an operating system to support more then one file system.


While many simpler operating systems support a limited range of options for accessing storage systems, more modern operating systems like UNIX and Linux support a technology known as a virtual file system or VFS. A modern operating system like UNIX supports a wide array of storage devices, regardless of their design or file systems to be accessed through a common application programming interface (API). This makes it unnecessary for programs to have any knowledge about the device they are accessing. A VFS allows the operating system to provide programs with access to an unlimited number of devices with an infinite variety of file systems installed on them through the use of specific device drivers and file system drivers. Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... This article is about operating systems that use the Linux kernel. ... A virtual file system (VFS) or virtual filesystem switch is an abstraction layer on top of a more concrete file system. ... For library and office filing systems, see Library classification. ... API and Api redirect here. ... A device driver, or software driver is a computer program allowing higher-level computer programs to interact with a computer hardware device. ...


A connected storage device such as a hard drive will be accessed through a device driver. The device driver understands the specific language of the drive and is able to translate that language into a standard language used by the operating system to access all disk drives. On UNIX this is the language of block devices. A storage device is a device used for storing something. ... Typical hard drives of the mid-1990s. ... A device driver, or software driver is a computer program allowing higher-level computer programs to interact with a computer hardware device. ...


When the kernel has an appropriate device driver in place, it can then access the contents of the disk 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 set of commands that the operating system can use to talk to all file systems. Programs can then deal with these file systems on the basis of filenames, and directories/folders, contained within a hierarchical structure. They can create, delete, open, and close files, as well as gathering various information about them, including access permissions, size, free space, and creation and modification dates.


Various differences between file systems make supporting all file systems difficult. Allowed characters in file names, case sensitivity, and the presence of various kinds of file attributes makes the implementation of a single interface for every file system a daunting task. Microsoft Windows presently supports only NTFS and FAT file systems, along with network file systems shared from other computers. Text sometimes exhibits case sensitivity, that is, words can differ in meaning based on the differing use of uppercase and lowercase letters. ... A file attribute is a piece of data that describes or is associated with a computer file. ... Windows redirects here. ... NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, and Windows Vista. ... File Allocation Table (FAT) is a partially patented file system developed by Microsoft for MS-DOS and was the primary file system for consumer versions of Microsoft Windows up to and including Windows Me. ... For the protocol of this name, see Network File System (protocol). ...


The visual representations of paths and filenames also differ under various platforms, although these are a more matter of preference and have little to do with the operating system's file system support. Unix demarcates its path components with a slash (/), a convention followed by operating systems that emulated it or at least its concept of hierarchical directories, such as Linux, Amiga OS and Mac OS X. MS-DOS also emulated this feature, but had already also adopted the CP/M convention of using slashes for additional options to commands, so instead MS-DOS used the backslash () as its component separator. Microsoft Windows continues with this convention; Japanese editions of Windows use ¥, and Korean editions use ₩.[1] Prior to Mac OS X, versions of Mac OS use a colon (:) for a path separator. RISC OS uses a period (.). Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... A path is the general form of a file or directory name, giving a files name and its unique location in a file system. ... This article is about operating systems that use the Linux kernel. ... AmigaOS is the default native operating system of the Amiga and AmigaOne personal computers. ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... CP/M is an operating system originally created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... The backslash ( ) is a typographical mark (glyph) used chiefly in computing. ... This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ... This article is about colons in punctuation. ... This article does not cite any references or sources. ...


UNIX and Unix-like operating systems allow for any character in file names other than the slash (/) and NULL characters, but allowing line feed (LF) and other control characters, which makes supporting those file systems under Microsoft Windows very difficult. UNIX file names are case sensitive, which allows multiple files to be created with names that differ only in case. By contrast, Microsoft Windows file names are not case sensitive by default, although NTFS supports case sensitivity at the file system level. Windows also has a larger set of punctuation characters that are not allowed in file names, most of which have been inherited from limitations in its original FAT file system. Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... Diagram of the relationships between several Unix-like systems A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... In computing, a newline is a special character or sequence of characters signifying the end of a line of text. ... NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, and Windows Vista. ...


File systems may provide journaling, which provides safe recovery in the event of a system crash. A journaled file system writes some information twice: first to the journal, which is a log of file system operations, then to its proper place in the ordinary file system. Journaling is handled by the file system driver, and keeps track of each operation taking place that changes the contents of the disk. In the event of a crash, the system can recover to a consistent state by replaying a portion of the journal. Many UNIX file systems provide journaling including ReiserFS, JFS, and Ext3. A journaling (or journalling) file system is a file system that logs changes to a journal (usually a circular log in a specially-allocated area) before actually writing them to the main file system. ... ReiserFS is a general-purpose, journaled computer file system designed and implemented by a team at Namesys led by Hans Reiser who is referred to as the projects Benevolent Dictator for Life. ... JFS is a three-letter abbreviation with multiple meanings: Jews Free School IBM Journaled File System 2 (JFS2) Journal of Food Science - the official scientific journal of the Institute of Food Technologists. ... The ext3 or third extended filesystem is a journalled file system that is commonly used by the Linux operating system. ...


In contrast, non-journaled file systems typically need to be examined in their entirety by a utility such as fsck or chkdsk for any inconsistencies after an unclean shutdown. Soft updates is an alternative to journaling that avoids the redundant writes by carefully ordering the update operations. Log-structured file systems and ZFS also differ from traditional journaled file systems in that they avoid inconsistencies by always writing new copies of the data, eschewing in-place updates. The system utility fsck (for file system check or file system consistency check) is a tool for checking the consistency of a file system in the Unix system and clones thereof. ... This article needs additional references or sources for verification. ... In computer file systems, soft updates are an approach to maintaining disk integrity after a crash or power outage. ... For other uses, see ZFS (disambiguation). ...


Many Linux distributions support some or all of ext2, ext3, ReiserFS, Reiser4, GFS, GFS2, OCFS, OCFS2, and NILFS. Linux also has full support for XFS and JFS, along with the FAT file systems, and NTFS. The ext2 or second extended file system is a file system for the Linux kernel. ... The ext3 or third extended filesystem is a journalled file system that is commonly used by the Linux operating system. ... ReiserFS is a general-purpose, journaled computer file system designed and implemented by a team at Namesys led by Hans Reiser who is referred to as the projects Benevolent Dictator for Life. ... Reiser4 is a computer file system, a new from scratch successor to the ReiserFS file system, developed by Namesys and sponsored by DARPA as well as Linspire. ... Global File System (or GFS) is a shared-storage journaled cluster, or distributed file system. ... Global File System (or GFS) is a shared-storage journaled cluster, or distributed file system. ... OCFS stands for Oracle Cluster File System. ... OCFS stands for Oracle Cluster File System. ... NILFS is a log-structured file system implementation for Linux. ... XFS is a high-performance journaling file system created by Silicon Graphics for their IRIX operating system. ... JFS is a journaling filesystem created by IBM. It is available under an open source license. ... File Allocation Table (FAT) is a partially patented file system developed by Microsoft for MS-DOS and was the primary file system for consumer versions of Microsoft Windows up to and including Windows Me. ... NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, and Windows Vista. ...


Microsoft Windows includes support for FAT12, FAT16, FAT32, and NTFS. The NTFS file system is the most efficient and reliable of the four Windows file systems, although details of its design are not known. As of Windows Vista, NTFS is the only file system which the operating system can be installed on. Windows Embedded CE 6.0 introduced ExFAT, a file system suitable for flash drives. File Allocation Table (FAT) is a file system that was developed for MS-DOS and used in consumer versions of Microsoft Windows up to and including Windows Me. ... File Allocation Table (FAT) is a file system that was developed for MS-DOS and used in consumer versions of Microsoft Windows up to and including Windows Me. ... File Allocation Table (FAT) is a file system that was developed for MS-DOS and used in consumer versions of Microsoft Windows up to and including Windows Me. ... NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, and Windows Vista. ... Windows Vista is a line of graphical operating systems used on personal computers, including home and business desktops, notebook computers, Tablet PCs, and media centers. ... NTFS is the standard file system of Windows NT, including its later versions Windows 2000, Windows XP, Windows Server 2003, Windows Server 2008, and Windows Vista. ... Windows Embedded CE 6. ... exFAT (Extended File Allocation Table, aka FAT64) is a proprietary file system suited especially for flash drives, introduced by Microsoft in Windows Embedded CE 6. ... A flash drive, related to a solid state drive, is a storage device that uses flash memory rather than conventional spinning platters to store data. ...


Mac OS X supports HFS+ with journaling as its primary file system. It is derived from the Hierarchical File System of the earlier Mac OS. Mac OS X has facilities to read and write FAT16, FAT32, NTFS, UDF, and other file systems, but cannot be installed to them. Also, due to its UNIX heritage Mac OS X now supports virtually all the file systems supported by the UNIX VFS. Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... HFS Plus or HFS+ is a file system developed by Apple Computer to replace their Hierarchical File System (HFS) as the primary file system used on Macintosh computers. ... Hierarchical File System (HFS), is a file system developed by Apple Computer for use on computers running Mac OS. Originally designed for use on floppy and hard disks, it can also be found on read-only media such as CD-ROMs. ... This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ...


FAT file systems are commonly found on floppy discs, flash memory cards, digital cameras, and many other portable devices because of its relative simplicity. ISO 9660 and Universal Disk Format are two common formats that target Compact Discs and DVDs, respectively. Mount Rainier is a newer extension to UDF, supported by Linux 2.6 kernels and Windows Vista that facilitates rewriting to DVDs in the same fashion as has been possible with floppy disks. For other uses, see FAT. Fats consist of a wide group of compounds that are generally soluble in organic solvents and largely insoluble in water. ... A floppy disk is a data storage device that comprises a circular piece of thin, flexible (hence floppy) magnetic storage medium encased in a square or rectangular plastic wallet. ... A USB flash drive. ... Look up digital camera in Wiktionary, the free dictionary. ... ISO 9660, a standard published by the International Organization for Standardization, defines a file system for CD-ROM media. ... The Universal Disk Format (UDF) is a format specification of a file system for storing files on optical media. ... CD redirects here. ... DVD (also known as Digital Versatile Disc or Digital Video Disc - see Etymology) is a popular optical disc storage media format. ... The Mount Rainier logo Mount Rainier is a format for re-writable optical discs which provides for packet writing and defect management. ...


Networking

Main article: Computer network

Current most operating systems support a variety of networking protocols, hardware, and applications for using them. This means that computers running dissimilar operating systems can 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 computer's operating system to access the resources of a remote computer to support the same functions as it could if those resources were connected directly to the local computer. This includes everything from simple communication, to using networked files systems or even sharing another computer's graphics or sound hardware. Some network services allow the resources of a computer to be accessed transparently, such as SSH which allows networked users direct access to a computer's command line interface. A computer network is an interconnection of a group of computers. ... A computer network is an interconnection of a group of computers. ... Remote procedure call (RPC) is a protocol that allows a computer program running on one computer to cause a subroutine on another computer to be executed without the programmer explicitly coding the details for this interaction. ... In computing, Secure shell, or SSH, is both a computer program and an associated network protocol designed for logging into and executing commands on a remote computer. ...


Client/server networking involves program on a computer somewhere which connects via a network to another computer, called a server. Servers, usually running UNIX or Linux, 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 program, which is responsible for handling requests to that port. A daemon, being a user program, can in turn access the local hardware resources of that computer by passing requests to the operating system kernel. In computer networking, the term network address may refer to one of the following: A network layer address, i. ...


Many operating systems support one or more vendor-specific or open networking protocols as well, for example, SNA on IBM systems, DECnet on systems from Digital Equipment Corporation, and Microsoft-specific protocols on Windows. Specific protocols for specific tasks may also be supported such as NFS for file access. Protocols like ESound, or esd can be easily extended over the network to provide sound from local applications, on a remote system's sound hardware. Virtual3D allows a remote computer to control local 3D graphics hardware, enabling things like 3D games to be played over a network. Systems Network Architecture (SNA) is IBMs proprietary networking architecture created in 1974. ... For other uses, see IBM (disambiguation) and Big Blue. ... DECnet is a proprietary suite of network protocols created by Digital Equipment Corporation, originally released in 1975 in order to connect two PDP-11 minicomputers. ... Digital Equipment Corporation was a pioneering American company in the computer industry. ... For network file systems in general, see network file system. ...


Security

Main article: computer security

A computer being secure depends on a number of technologies working properly. A modern operating system provides access to a number of resources, which are available to software running on the system, and to external devices like networks via the kernel. This article describes how security can be achieved through design and engineering. ...


The operating system must be capable of distinguishing between requesters which should be allowed to be processed, and others which should not be processed. While some systems may simply distinguish between "privileged" and "non-privileged", systems commonly have a form of requester identity, such as a user name. To establish identity there may be a process 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 be used instead. In some cases, especially connections from the network, resources may be accessed with no authentication at all.


In addition to the allow/disallow model of security, a system with a high level of security will also offer 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 program is only possible if all possibly harmful requests must be carried out through interrupts to the operating system kernel. If programs can directly access hardware and resources, they cannot be secured. Microsoft Windows has been heavily criticized for many years for window's almost total inability to protect one running program from another, however since windows isn't generally used as a server it has been considered less of a problem. In recent years, Microsoft has added limited user accounts, and more secure logins. However most people still operate their computers using Administrator accounts, which negates any possible internal security improvements brought about by these changes.


Linux and UNIX both have two tier security, which limits any system-wide changes to the root user, a special user account on all UNIX-like systems. While the root user has unlimited permission to affect system changes, programs as a regular user are limited only in where they can save files, and what hardware they can access. This limits the damage that a regular user can do to the computer while still providing them with plenty of freedom to do everything but affect system-wide changes. The user's settings are stored in an area of the computer's file system called the user's home directory, which is also provided as a location where the user may store their work, similar to My Documents on a windows system. Should a user have to install software or make system-wide changes, they must enter the root password for the computer, which allows them to launch certain programs as the root user.


While users generally find regular user accounts on Linux installations provide plenty of freedom for day to day activities, the need to enter a password to install software has generated criticisms from many Windows users who are used to being able to change, delete, create, and rename files anywhere on the system at whim, while also making it extremely easy to accidentally delete important files, and for viruses to infect the operating system. Windows Vista has attempted to make improvements in this area, but has also generated criticism for its highly inquisitive approach, asking the user verify their desire to do many daily activities that would rarely or never compromise security. Windows Vista is a line of graphical operating systems used on personal computers, including home and business desktops, notebook computers, Tablet PCs, and media centers. ...


External security involves a request from outside the computer, such as a login at a connected console or some kind of network connection. External requests are often passed through device drivers to the operating system's kernel, where they can be passed onto applications, or carried out directly. Security of operating systems has long been a concern because of highly sensitive data held on computers, both of a commercial and military nature. The United States Government Department of Defense (DoD) created the Trusted Computer System Evaluation Criteria (TCSEC) which is a standard that sets basic requirements for assessing the effectiveness of security. This became of vital importance to operating system makers, because the TCSEC was used to evaluate, classify and select computer systems being considered for the processing, storage and retrieval of sensitive or classified information. ... The United States Department of Defense (DOD or DoD) is the federal department charged with coordinating and supervising all agencies and functions of the government relating directly to national security and the military. ... The Orange Book Trusted Computer System Evaluation Criteria (TCSEC) is a United States Government Department of Defense (DoD) standard that sets basic requirements for assessing the effectiveness of computer security controls built into a computer system. ... A typical classified document. ...


Network services include offerings such as file sharing, print services, email, web sites, and file transfer protocols (FTP), most of which can have compromised security. At the front line of security are hardware devices known as firewalls or intrusion detection/prevention systems. At the operating system level, there are a number of software firewalls available, as well as intrusion detection/prevention systems. Most modern operating systems include a software firewall, which is enabled by default. A software firewall can be configured to allow or deny network traffic to or from a service or application running on the operating system. Therefore, one can install and be running an insecure service, such as Telnet or FTP, and not have to be threatened by a security breach because the firewall would deny all traffic trying to connect to the service on that port. This article is about the File Transfer Protocol standardised by the IETF. For other file transfer protocols, see File transfer protocol (disambiguation). ... This article is about the network security device. ...


An alternative strategy, and the only sandbox strategy available in systems that do not meet the Popek and Goldberg virtualization requirements, is the operating system not running user programs as native code, but instead either emulates a processor or provides a host for a p-code based system such as Java. In computer security, a sandbox is a is a play item for little kids, suppliers and untrusted users. ... The Popek and Goldberg virtualization requirements are a set of sufficient conditions for a computer architecture to efficiently support system virtualization. ... This article is about emulators in computer science. ... In computer programming, a P-code machine or pseudo-code machine is a specification of a cpu whose instructions are expected to be executed in software rather than in hardware (ie, interpreted). ...


Internal security is especially relevant for multi-user systems; it allows each user of the system to have private 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 bypass the operating system, inclusive of bypassing auditing.


Graphical user interfaces

Today, most modern computer systems contain Graphical User Interfaces. In some computer systems the GUI is integrated into the kernel—for example, in the original implementations of Microsoft Windows and Mac OS, the graphical subsystem was actually part of the kernel. Other operating systems, some older ones and some modern ones, are modular, separating the graphics subsystem from the kernel and the Operating System. In the 1980's UNIX, VMS and many others had operating systems that were built this way. Today Linux, and Mac OS X are also built this way. A graphical user interface (or GUI, pronounced gooey) is a method of interacting with a computer through a metaphor of direct manipulation of graphical images and widgets in addition to text. ... A kernel connects the application software to the hardware of a computer. ... Modularity is a concept that has applications in the contexts of computer science, particularly programming, as well as cognitive science in investigating the structure of mind. ...


Many computer operating systems allow the user to install or create any user interface they desire. The X Window System in conjunction with GNOME or KDE is a commonly found setup on most Unix and Unix-like (BSD, Linux, Minix) systems. Numerous Unix-based GUIs have existed over time, most derived from X11. Competition among the various vendors of Unix (HP, IBM, Sun) led to much fragmentation, though an effort to standardize in the 1990s to COSE and CDE failed for the most part due to various reasons, eventually eclipsed by the widespread adoption of GNOME and KDE. Prior to open source-based toolkits and desktop environments, Motif was the prevalent toolkit/desktop combination (and was the basis upon which CDE was developed). “X11” redirects here. ... This article is about the mythical creature. ... For the NYSE stock ticker symbol KDE, see 4Kids Entertainment. ... Diagram of the relationships between several Unix-like systems A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... MINIX is a free/open source, Unix-like operating system (OS) based on a microkernel architecture. ... The Common Open Software Environment or COSE was an initiative formed in March 1993 by the major Unix vendors of the time to create open, unified operating system (OS) standards. ... CDE on Unix (Solaris 8) DECwindows CDE on OpenVMS 7. ...


Graphical user interfaces evolve over time. For example, Windows has modified its user interface almost every time a new major version of Windows is released, and the Mac OS GUI changed dramatically with the introduction of Mac OS X in 2001.


Device drivers

Main article: Device driver

A device driver is a specific type of computer software developed to allow interaction with hardware devices. Typically this constitutes an interface for communicating with the device, through the specific computer bus or communications subsystem that the hardware is connected to, providing commands to and/or receiving data from the device, and on the other end, the requisite interfaces to the operating system and software applications. It is a specialized hardware-dependent computer program which is also operating system specific that enables another program, typically an operating system or applications software package or computer program running under the operating system 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. A device driver, or software driver is a computer program allowing higher-level computer programs to interact with a computer hardware device. ... A device driver, or software driver is a computer program allowing higher-level computer programs to interact with a computer hardware device. ...


The key design goal of device drivers is abstraction. Every model of hardware (even within the same class of device) is different. Newer models also 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 problem, OSes essentially dictate how every type of device should be controlled. The function of the device driver is then to translate these OS mandated function calls into device specific calls. In theory a new device, which is controlled in a new manner, should function correctly if a suitable driver is available. This new driver will ensure that the device appears to operate as usual from the operating systems' point of view for any person. This article is about the concept of abstraction in general. ...


History

Main article: History of operating systems
  • The first computers did not have operating systems. By the early 1960s, commercial computer vendors were supplying quite extensive tools for streamlining the development, scheduling, and execution of jobs on batch processing systems. Examples were produced by UNIVAC and Control Data Corporation, amongst others.
  • MS-DOS provided many operating system like features, such as disk access. However many DOS programs bypassed it entirely and ran directly on hardware.
  • The operating systems originally deployed on mainframes, and, much later, the original microcomputer operating systems, only supported one program at a time, requiring only a very basic scheduler. Each program was in complete control of the machine while it was running. Multitasking (timesharing) first came to mainframes in the 1960's.
  • In 1969-70, UNIX first appeared on the PDP-7 and later the PDP-11. It soon became capable of providing cross-platform time sharing using preemptive multitasking, advanced memory management, memory protection, and a host of other advanced features. UNIX soon gained popularity as an operating system for mainframes and minicomputers alike.
  • IBM microcomputers, including the IBM PC and the IBM PC XT could run Microsoft Xenix, a UNIX-like operating system from the early 1980s. Xenix was heavily marketed by Microsoft as a multi-user alternative to its single user MS-DOS operating system. The CPUs of these personal computer, could not facilitate kernel memory protection or provide dual mode operation, so Microsoft Xenix relied on cooperative multitasking and had no protected memory.
  • The 80286-based IBM PC AT was the first computer technically capable of using dual mode operation, and providing memory protection.
  • Classic Mac OS, and Microsoft Windows 1.0-Me supported only cooperative multitasking, and were very limited in their abilities to take advantage of protected memory. Application programs running on these operating systems must yield CPU time to the scheduler when they are not using it, either by default, or by calling a function.
  • Windows NT's underlying operating system kernel which was a designed by essentially the same team as Digital Equipment Corporation's VMS, a UNIX-like operating system which provided protected mode operation for all user programs, kernel memory protection, preemptive multi-tasking, virtual file system support, and a host of other features.
  • Classic AmigaOS and Windows 1.0-Me did not properly track resources allocated by processes at runtime. If a process had to be terminated, the resources might not be freed up for new programs until the machine was restarted.

The history of computer operating systems recapitulates to a degree, the recent history of computing. ... Insert non-formatted text hereBatch processing is the execution of a series of programs (jobs) on a computer without human interaction, when possible. ... UNIVAC serves as the catch-all name for the American manufacturers of the lines of mainframe computers by that name, which through mergers and acquisitions underwent numerous name changes. ... Control Data Corporation (CDC), was one of the pioneering supercomputer firms. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... Mainframes (often colloquially referred to as big iron) are large and expensive computers used mainly by government institutions and large companies for legacy applications, typically bulk data processing (such as censuses, industry/consumer statistics, ERP, and bank transaction processing). ... The Commodore 64 was one of the most popular microcomputers of its era, and is the best selling model of home computer of all time. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... A modified PDP-7 under restoration in Oslo, Norway The DEC PDP-7 is a minicomputer produced by Digital Equipment Corporation. ... The PDP-11 was a 16-bit minicomputer sold by Digital Equipment Corp. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... The IBM PC/XT (also written PC-XT or PC XT), commonly referred to as the XT, was IBMs successor to the original IBM PC. It was released on March 8, 1983, and was one of the first computers to come standard with a hard drive. ... Xenix was a version of the Unix operating system, licensed by Microsoft from AT&T in the late 1970s. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ... The Intel 80286 is an x86-family 16-bit microprocessor that was introduced by Intel on February 1, 1982. ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ... Windows redirects here. ... In computing, cooperative multitasking (or non-preemptive multitasking) is a form of multitasking in which multiple tasks execute by voluntarily ceding control to other tasks at programmer-defined points within each task. ... Windows NT (New Technology) is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... Digital Equipment Corporation was a pioneering American company in the computer industry. ... VMS is a three-letter abbreviation with multiple meanings, as described below: Virtual Memory System (another name for OpenVMS), an operating system Variable message sign, an electronic traffic sign often used on highways Visual Memory System (better known as Visual Memory Unit), a storage device for the Sega Dreamcast console... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... AmigaOS is the default native operating system of the Amiga personal computer. ...

Mainframes

Through the 1960s, many major features were pioneered in the field of operating systems. The development of the IBM System/360 produced a family of mainframe computers available in widely differing capacities and price points, for which a single operating system OS/360 was planned (rather than developing ad-hoc programs for every individual model). This concept of a single OS spanning an entire product line was crucial for the success of System/360 and, in fact, IBM's current mainframe operating systems are distant descendants of this original system; applications written for the OS/360 can still be run on modern machines. In the mid-70's, the MVS, the descendant of OS/360 offered the first[citation needed] implementation of using RAM as a transparent cache for disk resident data. For other uses, see IBM (disambiguation) and Big Blue. ... System/360 Model 65 operators console, with register value lamps and toggle switches (middle of picture) and emergency pull switch (upper right). ... For other uses, see Mainframe. ... OS/360 was a batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964. ... For other uses, see cache (disambiguation). ...


OS/360 also pioneered a number of concepts that, in some cases, are still not seen outside of the mainframe arena. For instance, in OS/360, when a program is started, the operating system keeps track of all of the system resources that are used including storage, locks, data files, and so on. When the process is terminated for any reason, all of these resources are re-claimed by the operating system. An alternative CP-67 system started a whole line of operating systems focused on the concept of virtual machines. VM is an early and influential virtual machine operating system from IBM, apparently the first true virtual machine system. ... In computer science, a virtual machine is software that creates a virtualized environment between the computer platform and its operating system, so that the end user can operate software on an abstract machine. ...


Control Data Corporation developed the SCOPE operating system 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 use. Like many commercial timesharing systems, its interface was an extension of the Dartmouth BASIC 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 time sharing networks. Plato was remarkably innovative for its time, featuring real-time chat, and multi-user graphical games. Control Data Corporation (CDC), was one of the pioneering supercomputer firms. ... SCOPE, an acronym for Simultaneous Control Of Program Execution, was the name used by the Control Data Corporation for a number of operating system projects in the 1960s. ...


Burroughs Corporation introduced the B5000 in 1961 with the MCP, (Master Control Program) operating system. The B5000 was a stack machine designed to exclusively support high-level languages with no machine language or assembler, and indeed the MCP was the first OS to be written exclusively in a high-level language – ESPOL, a dialect of ALGOL. MCP also introduced many other ground-breaking innovations, such as being the first commercial implementation of virtual memory. MCP is still in use today in the Unisys ClearPath/MCP line of computers. William Seward Burroughs (1857-1898), US inventor William S. Burroughs (1914-1997), author and grandson of William Seward Burroughs Edgar Rice Burroughs (1875-1950), American author of Tarzan fame The Burroughs Corporation began in 1886 as the American Arithmometer Company in St. ... Background The B5000 was designed in 1961 by a team at Burroughs under the leadership of Robert (Bob) Barton. ... To meet Wikipedias quality standards, this article may require cleanup. ... In computer science, a stack machine is a model of computation in which the computers memory takes the form of a stack. ... ESPOL (short for Executive Systems Programming Oriented Language) was a compiler for an ALGOL 60 superset that provided capabilities of that would later be known as Mohols, machine oriented high order languages, such as interrupting a processor on a multiprocessor system (the Burroughs B5000 was a dual-processor system). ... It has been suggested that ALGOL object code be merged into this article or section. ... This article is about the computer term. ... Unisys Corporation (NYSE: UIS), based in Blue Bell, Pennsylvania, United States, and incorporated in Delaware[3], is a global provider of information technology services and solutions. ...


UNIVAC, the first commercial computer manufacturer, produced a series of EXEC operating systems. Like all early main-frame systems, this was a batch-oriented system that managed magnetic drums, disks, card readers and line printers. In the 1970s, UNIVAC produced the Real-Time Basic (RTB) system to support large-scale time sharing, also patterned after the Dartmouth BASIC system.


General Electric and MIT developed General Electric Comprehensive Operating Supervisor (GECOS), which introduced the concept of ringed security privilege levels. After acquisition by Honeywell it was renamed to General Comprehensive Operating System (GCOS). To meet Wikipedias quality standards, this article or section may require cleanup. ...


Digital Equipment Corporation developed many operating systems for its various computer lines, including TOPS-10 and TOPS-20 time sharing systems for the 36-bit PDP-10 class systems. Prior to the widespread use of UNIX, TOPS-10 was a particularly popular system in universities, and in the early ARPANET community. The TOPS-10 System was a computer operating system from Digital Equipment Corporation (DEC) for the PDP-10 released in 1964 and later on for the DEC-System10. ... The TOPS-20 operating system by DEC was the second proprietary OS for the PDP-10. ...


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


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

To meet Wikipedias quality standards, this article may require cleanup. ... The Burroughs large systems were the largest of three series of Burroughs Corporation mainframe computers. ... Unisys Corporation (NYSE: UIS), based in Blue Bell, Pennsylvania, United States, and incorporated in Delaware[3], is a global provider of information technology services and solutions. ... OS/360 was a batch processing operating system developed by IBM for their then-new System/360 mainframe computer, announced in 1964. ... System/360 Model 65 operators console, with register value lamps and toggle switches (middle of picture) and emergency pull switch (upper right). ... z/OS Welcome Screen seen through a terminal emulator The title of this article begins with a capital letter due to technical limitations. ... VM is an early and influential virtual machine operating system from IBM, apparently the first true virtual machine system. ... System/360 Model 65 operators console, with register value lamps and toggle switches (middle of picture) and emergency pull switch (upper right). ... VM is an early and influential virtual machine operating system from IBM, apparently the first true virtual machine system. ... EXEC 8 (sometimes referred to as EXEC VIII) was UNIVACs operating system developed for the UNIVAC 1108 in 1964. ... The UNIVAC 1108 was the second member of Sperry Rands UNIVAC 1100 series of computers, introduced in 1964. ... Unisys Corporation (NYSE: UIS), based in Blue Bell, Pennsylvania, United States, and incorporated in Delaware[3], is a global provider of information technology services and solutions. ...

Microcomputers

The first microcomputers did not have the capacity or need for the elaborate operating systems that had been developed for mainframes and minis; minimalistic operating systems were developed, often loaded from ROM and known as Monitors. One notable early disk-based operating system was CP/M, which was supported on many early microcomputers and was closely imitated in MS-DOS, which became wildly popular as the operating system chosen for the IBM PC (IBM's version of it was called IBM-DOS or PC-DOS), its successors making Microsoft one of the world's most profitable companies. In the 80's Apple Computer Inc. (now Apple Inc.) abandoned its popular Apple II series of microcomputers to introduce the Apple Macintosh computer with the an innovative Graphical User Interface (GUI) to the Mac OS. The Commodore 64 was one of the most popular microcomputers of its era, and is the best selling model of home computer of all time. ... Read-only memory (usually known by its acronym, ROM) is a class of storage media used in computers and other electronic devices. ... CP/M is an operating system originally created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... IBM PC-DOS was one of the three major operating systems that dominated the personal computer market from about 1985 to 1995. ... Microsoft Corporation, (NASDAQ: MSFT, HKSE: 4338) is a multinational computer technology corporation with global annual revenue of US$44. ... Apple Inc. ... The Apple II was one of the most popular personal computers of the 1980s. ... The first Macintosh computer, introduced in 1984, upgraded to a 512K Fat Mac. The Macintosh or Mac, is a line of personal computers designed, developed, manufactured, and marketed by Apple Computer. ... GUI redirects here. ... This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ...


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's responded to this progress by hiring Dave Cutler, who had developed the VMS operating system for Digital Equipment Corporation. He would lead the development of the Windows NT operating system, which continues to serve as the basis for Microsoft's operating systems line. Steve Jobs, a co-founder of Apple Inc., started NeXT Computer Inc., which developed the Unix-like 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 Intel386[1] is a microprocessor which was used as the central processing unit (CPU) of many personal computers from 1986 until 2007. ... CPU can stand for: in computing: Central processing unit in journalism: Commonwealth Press Union in law enforcement: Crime prevention unit in software: Critical patch update, a type of software patch distributed by Oracle Corporation in Macleans College is often known as Ash Lim. ... 32-bit is a term applied to processors, and computer architectures which manipulate the address and data in 32-bit chunks. ... In computer operating systems, paging memory allocation, paging refers to the process of managing program access to virtual memory pages that do not currently reside in RAM. It is implemented as a task that resides in the kernel of the operating system and gains control when a page fault takes... In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is... HP2114 minicomputer Minicomputer is a largely obsolete term for a class of multi-user computers which make up the middle range of the computing spectrum, in between the largest multi-user systems (mainframe computers) and the smallest single-user systems (microcomputers or personal computers). ... Mainframes (often colloquially referred to as big iron) are large and expensive computers used mainly by government institutions and large companies for legacy applications, typically bulk data processing (such as censuses, industry/consumer statistics, ERP, and bank transaction processing). ... David Neil Cutler, Sr. ... VMS is a three-letter abbreviation with multiple meanings, as described below: Virtual Memory System (another name for OpenVMS), an operating system Variable message sign, an electronic traffic sign often used on highways Visual Memory System (better known as Visual Memory Unit), a storage device for the Sega Dreamcast console... Digital Equipment Corporation was a pioneering American company in the computer industry. ... Windows NT (New Technology) is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... Steve Jobs (born Steven Paul Jobs February 24, 1955) is the CEO, chairman and co-founder of Apple Inc. ... Apple Inc. ... For other meanings, see Next. ... Diagram of the relationships between several Unix-like systems A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... NEXTSTEP is the original object-oriented, multitasking operating system that NeXT Computer, Inc. ... Apple Inc. ... FreeBSD is a Unix-like free operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD) branch through the 386BSD and 4. ...


Minix, an academic teaching tool which could be run on early PCs, would inspire another reimplementation of Unix, called Linux. Started by computer student Linus Torvalds with cooperation from volunteers over the internet, developed a kernel which was combined with the tools from the GNU Project. The Berkeley Software Distribution, known as BSD, is the UNIX derivative distributed by the University of California, Berkeley, starting in the 1970s. Freely distributed and ported to many minicomputers, it eventually also gained a following for use on PCs, mainly as FreeBSD, NetBSD and OpenBSD. MINIX is a free/open source, Unix-like operating system (OS) based on a microkernel architecture. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... This article is about operating systems that use the Linux kernel. ... Linus Benedict Torvalds   (born December 28, 1969 in Helsinki, Finland) is a Finnish software engineer best known for initiating the development of the Linux kernel. ... Look up Kernel in Wiktionary, the free dictionary. ... The GNU logo, drawn by Etienne Suvasa The GNU Project was announced in 1983 by Richard Stallman. ... Berkeley Software Distribution (BSD, sometimes called Berkeley Unix) is the Unix derivative distributed by the University of California, Berkeley, starting in the 1970s. ... In computer science, porting is the adaptation of a piece of software so that it will function in a different computing environment to that for which it was originally written. ... FreeBSD is a Unix-like free operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD) branch through the 386BSD and 4. ... NetBSD is a freely redistributable, open source version of the Unix-like BSD computer operating system. ... OpenBSD is a Unix-like computer operating system descended from Berkeley Software Distribution (BSD), a Unix derivative developed at the University of California, Berkeley. ...


Some Operating Systems

Microsoft Windows

The Microsoft Windows family of operating systems originated as an add-on to the older MS-DOS operating system for the IBM PC. Modern versions are based on the newer Windows NT kernel that was originally intended for OS/2 and borrowed from VMS. Windows runs on x86, x86-64 and Itanium processors. Earlier versions also ran on the DEC Alpha, MIPS, Fairchild (later Intergraph) Clipper and PowerPC architectures (some work was done to port it to the SPARC architecture). Windows redirects here. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... IBM PC (IBM 5150) with keyboard and green screen monochrome monitor (IBM 5151), running MS-DOS 5. ... Windows NT (New Technology) is a family of operating systems produced by Microsoft, the first version of which was released in July 1993. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... VMS is a three-letter abbreviation with multiple meanings, as described below: Virtual Memory System (another name for OpenVMS), an operating system Variable message sign, an electronic traffic sign often used on highways Visual Memory System (better known as Visual Memory Unit), a storage device for the Sega Dreamcast console... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... The AMD64 or x86-64 is a 64-bit processor architecture invented by AMD. It is a superset of the x86 architecture, which it natively supports. ... 2007 Itanium logo Itanium is the brand name for 64-bit Intel microprocessors that implement the Intel Itanium architecture (formerly called IA-64). ... DEC Alpha AXP 21064 Microprocessor die photo Package for DEC Alpha AXP 21064 Microprocessor Alpha AXP 21064 bare die mounted on a business card with some statistics The DEC Alpha, also known as the Alpha AXP, is a 64-bit RISC microprocessor originally developed and fabricated by Digital Equipment Corp... A MIPS R4400 microprocessor made by Toshiba. ... Fairchild Semiconductor introduced the first commercially available integrated circuit (although at almost the same time as one from Texas Instruments), and would go on to become one of the major players in the evolution of Silicon Valley in the 1960s. ... Intergraph was founded in 1969 as M&S Computing, Inc. ... The Clipper architecture is a 32-bit RISC-like instruction set architecture designed by Fairchild Semiconductor. ... PowerPC is a RISC microprocessor architecture created by the 1991 Apple–IBM–Motorola alliance, known as AIM. Originally intended for personal computers, PowerPC CPUs have since become popular embedded and high-performance processors as well. ... Sun UltraSPARC II Microprocessor Sun UltraSPARC T1 (Niagara 8 Core) SPARC (Scalable Processor Architecture) is a RISC microprocessor instruction set architecture originally designed in 1985 by Sun Microsystems. ...


As of September 2007, Microsoft Windows holds a large amount of the worldwide desktop market share. Windows is also used on servers, supporting applications such as web servers and database servers. In recent years, Microsoft has spent significant marketing and research & development money to demonstrate that Windows is capable of running any enterprise application, which has resulted in consistent price/performance records (see the TPC) and significant acceptance in the enterprise market. Market share, in strategic management and marketing, is the percentage or proportion of the total available market or market segment that is being serviced by a company. ... The inside/front of a Dell PowerEdge web server The term Web server can mean one of two things: A computer program that is responsible for accepting HTTP requests from clients, which are known as Web browsers, and serving them HTTP responses along with optional data contents, which usually are... A database management system (DBMS) is a computer program (or more typically, a suite of them) designed to manage a database, a large set of structured data, and run operations on the data requested by numerous users. ... Transaction Processing Performance Council (TPC) is a not-for-profit organization which sets performance benchmarks for IT applications, such as databases. ...


The most widely used version of the Microsoft Windows family is Windows XP, released on October 25, 2001. Windows XP is a line of operating systems developed by Microsoft for use on general-purpose computer systems, including home and business desktops, notebook computers, and media centers. ... is the 298th day of the year (299th in leap years) in the Gregorian calendar. ... This article is about the year. ...


In November 2006, after more than five years of development work, Microsoft released Windows Vista, a major new operating system version of Microsoft Windows family which contains a large number of new features and architectural changes. Chief amongst these are a new user interface and visual style called Windows Aero, a number of new security features such as User Account Control, and few new multimedia applications such as Windows DVD Maker. Windows Vista is a line of graphical operating systems used on personal computers, including home and business desktops, notebook computers, Tablet PCs, and media centers. ... Windows Vista (formerly codenamed Longhorn) has many significant new features compared with previous Microsoft Windows versions, covering most aspects of the operating system. ... Windows Aero is the graphical user interface for Windows Vista, an operating system released by Microsoft in November 2006. ... UAC confirmation dialog UAC credentials dialog User Account Control (UAC) is a technology and security infrastructure introduced with Microsofts Windows Vista operating system. ... Windows DVD Maker is an application included in premium editions (Home Premium and Ultimate) of Windows Vista that is designed to enable the creation of DVD movies in Windows. ...


Microsoft has announced a new version codenamed Windows 7 will be released in late 2009 - mid 2010 Windows 7 (formerly codenamed Blackcomb, then Vienna) is a future version of Microsoft Windows. ...


Plan 9

Ken Thompson, Dennis Ritchie and Douglas McIlroy at Bell Labs designed and developed the C programming language to build the operating system Unix. Programmers at Bell Labs went on to develop Plan 9 and Inferno, which were engineered for modern distributed environments. Plan 9 was designed from the start to be a networked operating system, and had graphics built-in, unlike Unix, which added these features to the design later. Plan 9 has yet to become as popular as Unix derivatives, but it has an expanding community of developers. It is currently released under the Lucent Public License. Inferno was sold to Vita Nuova Holdings and has been released under a GPL/MIT license. Kenneth Thompson redirects here. ... Dennis Ritchie Dennis MacAlistair Ritchie (born September 9, 1941) is a computer scientist notable for his influence on ALTRAN, B, BCPL, C, Multics, and Unix. ... Portrait of Douglas McIlroy taken at the NATO conference in Garmisch 1968, courtesy of Brian Randell. ... Bell Laboratories (also known as Bell Labs and formerly known as AT&T Bell Laboratories and Bell Telephone Laboratories) was the main research and development arm of the United States Bell System. ... Plan 9 from Bell Labs is a distributed operating system, primarily used as a research vehicle. ... Inferno is an operating system for creating and supporting distributed services. ... The Lucent Public License is an open-source license created by Lucent Technologies. ... Vita Nuova Holdings Ltd is an English company based in York that provides technology for embedded systems and distributed applications based upon the unique operating system Inferno. ...


Unix and Unix-like operating systems

A customized KDE desktop running under Linux.

Ken Thompson wrote B, mainly based on BCPL, which he used to write Unix, based on his experience in the MULTICS project. B was replaced by C, and Unix developed into a large, complex family of inter-related operating systems which have been influential in every modern operating system (see History). Image File history File links Download high-resolution version (1024x768, 110 KB) Summary A customized Linux desktop. ... Image File history File links Download high-resolution version (1024x768, 110 KB) Summary A customized Linux desktop. ... For the NYSE stock ticker symbol KDE, see 4Kids Entertainment. ... This article is about operating systems that use the Linux kernel. ... Kenneth Thompson redirects here. ... B was the name of a programming language developed at Bell Labs. ... BCPL (Basic Combined Programming Language) is a computer programming language that was designed by Martin Richards of the University of Cambridge in 1966; it was originally intended for use in writing compilers for other languages. ... Multics (Multiplexed Information and Computing Service) was an extraordinarily influential early time-sharing operating system. ... C is a general-purpose, block structured, procedural, imperative computer programming language developed in 1972 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system. ... The history of computer operating systems recapitulates to a degree, the recent history of computing. ...


The Unix-like family is a diverse group of operating systems, with several major sub-categories including System V, BSD, and Linux. The name "UNIX" is a trademark of The Open Group which licenses it for use with any 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. Diagram of the relationships between several Unix-like systems A Unix-like operating system is one that behaves in a manner similar to a Unix system, while not necessarily conforming to or being certified to any version of the Single UNIX Specification. ... AT&T UNIX System V was one of the versions of the UNIX operating system. ... Berkeley Software Distribution (BSD, sometimes called Berkeley Unix) is the Unix derivative distributed by the University of California, Berkeley, starting in the 1970s. ... This article is about operating systems that use the Linux kernel. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... This article or section reads like an advertisement. ...


Unix-like systems run on a wide variety of machine architectures. They are used heavily for servers in business, as well as workstations in academic and engineering environments. Free software Unix variants, such as GNU, Linux and BSD, are popular in these areas. The market share for Linux is divided between many different distributions. Enterprise class distributions by Red Hat or Novell are used by corporations, but some home users may use those products. Historically home users typically installed a distribution themselves, but in 2007 Dell began to offer the Ubuntu Linux distribution on home PCs. Linux on the desktop is also popular in the developer and hobbyist operating system development communities. (see below) In information technology, a server is an application or device that performs services for connected clients as part of a client-server architecture. ... Sun SPARCstation 1+, 25 MHz RISC processor from early 1990s A workstation, such as a Unix workstation, RISC workstation or engineering workstation, is a high-end desktop or deskside microcomputer designed for technical applications. ... Free software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with minimal restrictions only to ensure that further recipients can also do these things. ... GNU (pronounced ) is a computer operating system composed entirely of free software. ... This article is about operating systems that use the Linux kernel. ... BSD redirects here. ... A Linux distribution, often simply distribution or distro, is a member of the Linux family of Unix-like operating systems comprising the Linux kernel, the non-kernel parts of the GNU operating system, and assorted other software. ... For other uses, see Red Hat (disambiguation). ... For the road bicycle racing team previously known as Novell, see Rabobank (cycling). ... This article is about the corporation Dell, Inc. ... Ubuntu (IPA pronunciation (oo-BOON-too[5])) is a predominantly desktop-oriented Linux distribution, based on Debian GNU/Linux but with a stronger focus on usability, regular releases, and ease of installation at the expense of platform diversity. ... This article is about pastimes. ... Operating system development refers to the development of operating systems, usually as a hobby realized by people not constituting a company. ...


Market share statistics for freely available operating systems are usually inaccurate since most free operating systems are not purchased, making usage under-represented. On the other hand, market share statistics based on total downloads of free operating systems are often inflated, as there is no economic disincentive to acquire multiple operating systems so users can download multiple systems, test them, and decide which they like best.


Some Unix variants like HP's HP-UX and IBM's AIX are designed to run only on that vendor's hardware. Others, such as Solaris, can run on multiple types of hardware, including x86 servers and PCs. Apple's Mac OS X, a hybrid kernel-based BSD variant derived from NeXTSTEP, Mach, and FreeBSD, has replaced Apple's earlier (non-Unix) Mac OS. HP-UX (Hewlett Packard UniX) is Hewlett-Packards proprietary implementation of the Unix operating system, based on System V (initially System III). ... AIX (Advanced Interactive eXecutive) is a proprietary operating system developed by IBM based on UNIX System V. Before the product was ever marketed, the acronym AIX originally stood for Advanced IBM UNIX. AIX has pioneered numerous network operating system enhancements, introducing new innovations later adopted by Unix-like operating systems... Solaris is a computer operating system developed by Sun Microsystems. ... x86 or 80x86 is the generic name of a microprocessor architecture first developed and manufactured by Intel. ... Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... Graphical overview of a hybrid kernel Hybrid kernel is a kernel architecture based on combining aspects of microkernel and monolithic kernel architectures used in computer operating systems. ... NEXTSTEP is the original object-oriented, multitasking operating system that NeXT Computer, Inc. ... Mach is an operating system microkernel developed at Carnegie Mellon University to support operating system research, primarily distributed and parallel computation. ... FreeBSD is a Unix-like free operating system descended from AT&T UNIX via the Berkeley Software Distribution (BSD) branch through the 386BSD and 4. ...


Unix interoperability was sought by establishing the POSIX standard. The POSIX standard can be applied to any operating system, although it was originally created for various Unix variants. POSIX or Portable Operating System Interface[1] is the collective name of a family of related standards specified by the IEEE to define the application programming interface (API) for software compatible with variants of the Unix operating system. ...


Mac OS X

Mac OS X is a line of proprietary, graphical operating systems developed, marketed, and sold by Apple Inc., the latest of which is pre-loaded on all currently shipping Macintosh computers. Mac OS X is the successor to the original Mac OS, which had been Apple's primary operating system since 1984. Unlike its predecessor, Mac OS X is a UNIX operating system built on technology that had been developed at NeXT through the second half of the 1980s and up until Apple purchased the company in early 1997. Mac OS X (pronounced ) is a line of graphical operating systems developed, marketed, and sold by Apple Inc. ... Proprietary software is software with restrictions on copying and modifying as enforced by the proprietor. ... Apple Inc. ... For other uses, see Macintosh (disambiguation) and Mac. ... This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... For other meanings, see Next. ...


The operating system was first released in 1999 as Mac OS X Server 1.0, with a desktop-oriented version (Mac OS X v10.0) following in March 2001. Since then, five more distinct "end-user" and "server" editions of Mac OS X have been released, the most recent being Mac OS X v10.5, which was first made available in October 2007. Releases of Mac OS X are named after big cats; Mac OS X v10.5 is usually referred to by Apple and users as "Leopard". Mac OS X Server 1. ... Mac OS X version 10. ... Mac OS X version 10. ... For people nicknamed The Big Cat, see The Big Cat. ...


The server edition, Mac OS X Server, is architecturally identical to its desktop counterpart but usually runs on Apple's line of Macintosh server hardware. Mac OS X Server includes workgroup management and administration software tools that provide simplified access to key network services, including a mail transfer agent, a Samba server, an LDAP server, a domain name server, and others. Mac OS X Server is the server-oriented version of Apples operating system, Mac OS X. Mac OS X, in both desktop and server versions, is a Unix operating system based on technology that Apple acquired from NeXT Computer. ... The software architecture of a program or computing system is the structure or structures of the system, which comprise software components, the externally visible properties of those components, and the relationships between them. ... In information technology, a server is an application or device that performs services for connected clients as part of a client-server architecture. ... Network services are the foundation of a networked computing environment. ... A mail transfer agent or MTA (also called a mail transport agent, mail server, or a mail exchanger in the context of the Domain Name System) is a computer program or software agent that transfers electronic mail messages from one computer to another. ... Samba logo. ... Lightweight Directory Access Protocol (LDAP) is a protocol for accessing on-line directory services. ... The Domain Name System (DNS) associates various sorts of information with so-called domain names; most importantly, it serves as the phone book for the Internet by translating human-readable computer hostnames, e. ...


Embedded systems

Embedded systems use a variety of dedicated operating systems. In some cases, the "operating system" software is directly linked to the application to produce a monolithic special-purpose program. In the simplest embedded systems, there is no distinction between the OS and the application. Embedded systems that have certain time requirements are known as real-time operating systems. A router, an example of an embedded system. ... A real-time operating system (RTOS)[Generally pronounced as: Or-tos] is a multitasking operating system intended for real-time applications. ...


Operating systems such as VxWorks, eCos, and Palm OS, are unrelated to Unix and Windows. Windows CE shares similar APIs to desktop Windows but shares none of desktop Windows' codebase, and several embedded BSD and Linux distributions exist. VxWorks is a Unix-like real-time operating system made and sold by Wind River Systems of Alameda, California, USA. Like most RTOSes, VxWorks includes a multitasking kernel with pre-emptive scheduling and fast interrupt response, extensive inter-process communications and synchronization facilities, and a file system. ... The correct title of this article is . ... Palm OS is an embedded operating system initially developed by U.S. Robotics owned Palm Computing, Inc. ... Windows CE (sometimes abbreviated WinCE) is a variation of Microsofts Windows operating system for minimalistic computers and embedded systems. ... Berkeley Software Distribution (BSD, sometimes called Berkeley Unix) is the Unix derivative distributed by the University of California, Berkeley, starting in the 1970s. ... This article is about operating systems that use the Linux kernel. ...


However Linux has recently pulled ahead as a leader in embedded operating systems, due to its lack of royalties, vast capabilities, high performance, and potentially tiny memory footprint.


Hobby operating system development

Operating system development, or OSDev for short, as a hobby has a large cult-like following. As such, operating systems, such as Linux, have derived from hobby operating system projects. The design and implementation of an operating system requires skill and determination, and the term can cover anything from a basic "Hello World" boot loader to a fully featured kernel. One classical example of this is the Minix Operating System—an OS that was designed as a teaching tool but was heavily used by hobbyists before Linux eclipsed it in popularity. Operating system development refers to the development of operating systems, usually as a hobby realized by people not constituting a company. ... This article is about operating systems that use the Linux kernel. ... A hello world program is a computer program that prints out Hello, World! on a display device. ... MINIX is a free/open source, Unix-like operating system (OS) based on a microkernel architecture. ... This article is about operating systems that use the Linux kernel. ...


Other

Older operating systems which are still used in niche markets include OS/2 from IBM; Mac OS, the non-Unix precursor to Apple's Mac OS X; BeOS; XTS-300. Some, most notably AmigaOS and RISC OS, continue to be developed as minority platforms for enthusiast communities and specialist applications. OpenVMS formerly from DEC, is still under active development by Hewlett-Packard. To meet Wikipedias quality standards, this article or section may require cleanup. ... This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ... BeOS is an operating system for personal computers which began development by Be Inc. ... The XTS-400 is a multi-level secure computer system. ... AmigaOS is the default native operating system of the Amiga personal computer. ... This article does not cite any references or sources. ... OpenVMS[1] (Open Virtual Memory System or just VMS) is the name of a high-end computer server operating system that runs on the VAX[2] and Alpha[3] family of computers developed by Digital Equipment Corporation of Maynard, Massachusetts (DIGITAL was then purchased by Compaq, and is now owned... Digital Equipment Corporation was a pioneering American company in the computer industry. ... The Hewlett-Packard Company (NYSE: HPQ), commonly known as HP, is a very large, global company headquartered in Palo Alto, California, United States. ...


Research and development of new operating systems continues. GNU Hurd is designed to be backwards compatible with Unix, but with enhanced functionality and a microkernel architecture. Singularity is a project at Microsoft Research to develop an operating system with better memory protection based on the .Net managed code model. Hurd redirects here. ... Singularity is a Microsoft Research project to build a highly-dependable operating system in which the kernel, device driver, and applications are all written in managed code. ... Microsoft Research (MSR) is a division of Microsoft created in 1991 for researching various computer science topics and issues. ... Memory protection is a system that prevents one process from corrupting the memory of another process running on the same computer at the same time. ...


References

  1. ^ Michael Kaplan (September 17, 2005). When is a backslash not a backslash?. MSDN Blogs. Retrieved on 2007-10-24.

Bibliography is the 260th day of the year (261st in leap years) in the Gregorian calendar. ... Year 2005 (MMV) was a common year starting on Saturday (link displays full calendar) of the Gregorian calendar. ... MSDN Blogs [1] is Microsofts blog site where many of its employees blog to a public audience. ... Year 2007 (MMVII) was a common year starting on Monday of the Gregorian calendar in the 21st century. ... is the 297th day of the year (298th in leap years) in the Gregorian calendar. ...

  • Auslander, Marc A.; Larkin, David C.; Scherr, Allan L.. "The evolution of the MVS Operating System". IBM J. Research & Development. http://www.research.ibm.com/journal/rd/255/auslander.pdf
  • Deitel, Harvey M.; Deitel, Paul; Choffnes, David. Operating Systems. Pearson/Prentice Hall. ISBN 978-0-13-092641-8. 
  • Bic, Lubomur F.; Shaw, Alan C. (2003). Operating Systems.. Pearson: Prentice Hall. 
  • Stallings (2005). Operating Systems, Internals and Design Principles. Pearson: Prentice Hall. 

Pearson can mean Pearson PLC the media conglomerate. ... Pearson can mean Pearson PLC the media conglomerate. ...

See also

Operating systems can be categorized by technology, ownership, licensing, working state, usage, and by many other characteristics. ... These tables compare general and technical information for a number of widely used and currently available operating systems. ... This article presents a timeline of events in the history of computer operating systems from 1960 to 2007. ... The phrase trusted operating system generally refers to an operating system that provides sufficient support for multilevel security and evidence of correctness to meet a particular set of government requirements. ... This is a list of important publications in computer science, organized by field. ... A kernel connects the application software to the hardware of a computer. ... In computing, a system call is the mechanism used by an application program to request service from the operating system. ... Orthogonal persistence refers to inherent support provided by a programming language or operating system of a computer that enables the state of programs written in the persistent programming language, or of the operating system itself, to remain persistent even after a crash or unexpected shutdown. ... An object-oriented operating system is an operating system which internally uses object-oriented methodologies. ... Disk Operating System (specifically) and disk operating system (generically), most often abbreviated as DOS (not to be confused with the DOS family of disk operating systems for the IBM PC compatible platform), refer to operating system software used in most computers that provides the abstraction and management of secondary storage... It has been suggested that Apple evangelist be merged into this article or section. ...

External links

Look up Operating system in
Wiktionary, the free dictionary.

Wiktionary (a portmanteau of wiki and dictionary) is a multilingual, Web-based project to create a free content dictionary, available in over 151 languages. ... The Open Directory Project (ODP), also known as dmoz (from , its original domain name), is a multilingual open content directory of World Wide Web links owned by Netscape that is constructed and maintained by a community of volunteer editors. ... A kernel connects the application software to the hardware of a computer. ... Graphical overview of a microkernel A microkernel is a minimal computer operating system kernel providing only basic operating system services (system calls), while other services (commonly provided by kernels) are provided by user-space programs called servers. ... It has been suggested that Monolithic system be merged into this article or section. ... Graphical overview of a hybrid kernel Hybrid kernel is a kernel architecture based on combining aspects of microkernel and monolithic kernel architectures used in computer operating systems. ... In computer engineering the kernel is the core of an operating system. ... In computing, loadable kernel modules, or LKM, are object files that contain code to extend the running kernel, or so-called base kernel, of an operating system. ... In computer science, a nanokernel or picokernel is a very minimalist operating system kernel. ... A device driver, or software driver is a computer program allowing higher-level computer programs to interact with a computer hardware device. ... An operating system usually segregates the available system memory into kernel space and user space. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Process management is the ensemble of activities of planning and monitoring the performance of a process, especially in the sense of business process, often confused with reengineering. ... In computing, a process is an instance of a computer program that is being executed. ... In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is... In computing, an interrupt is an asynchronous signal from hardware or software indicating the need for attention. ... Protected mode is an operational mode of x86-compatible CPUs of the 80286 series or later. ... In computer terms, supervisor mode is a hardware-mediated flag which can be changed by code running in system-level software. ... In computing, multitasking is a method by which multiple tasks, also known as processes, share common processing resources such as a CPU. In the case of a computer with a single CPU, only one task is said to be running at any point in time, meaning that the CPU is... For disk scheduling, see I/O scheduling. ... A context switch is the computing process of storing and restoring the state (context) of a CPU such that multiple processes can share a single CPU resource. ... In computing, cooperative multitasking (or non-preemptive multitasking) is a form of multitasking in which multiple tasks execute by voluntarily ceding control to other tasks at programmer-defined points within each task. ... Pre-emptive multitasking is a form of multitasking in which processes are not allowed to take an indefinitely long time to complete execution in the CPU. Each process, in turn, is granted a portion of CPU time (usually called a time slice, on the order of milliseconds). ... CPU modes (also called processor modes or privilege levels, and by other names) are operating modes for the central processing unit of some computers that place variable restrictions on the operations that can be performed by the CPU. Mode types At a minimum, any CPU with this type of architecture... Memory protection is a system that prevents one process from corrupting the memory of another process running on the same computer at the same time. ... Look up segmentation in Wiktionary, the free dictionary. ... In computer operating systems, paging memory allocation, paging refers to the process of managing program access to virtual memory pages that do not currently reside in RAM. It is implemented as a task that resides in the kernel of the operating system and gains control when a page fault takes... This 68451 MMU could be used with the Motorola 68010 MMU, short for memory management unit or sometimes called paged memory management unit as PMMU, is a class of computer hardware components responsible for handling memory accesses requested by the CPU. Among the functions of such devices are the translation... It has been suggested that Access violation be merged into this article or section. ... A General Protection Fault (GPF) in the Intel x86 and AMD x86-64 architectures is a fault (a type of an interrupt) which can encompass several cases, where protection mechanisms within the processor architecture are violated by any of the programs that is running, whether it be the kernel or... AmigaOS is the default native operating system of the Amiga and AmigaOne personal computers. ... Filiation of Unix and Unix-like systems Unix (officially trademarked as UNIX®, sometimes also written as or ® with small caps) is a computer operating system originally developed in 1969 by a group of AT&T employees at Bell Labs including Ken Thompson, Dennis Ritchie and Douglas McIlroy. ... This article is about operating systems that use the Linux kernel. ... GNU (pronounced ) is a computer operating system composed entirely of free software. ... CP/M is an operating system originally created for Intel 8080/85 based microcomputers by Gary Kildall of Digital Research, Inc. ... MP/M was the multi-user version of the CP/M operating system, created by Digital Research. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Microsofts disk operating system, MS-DOS, was Microsofts implementation of DOS, which was the first popular operating system for the IBM PC, and until recently, was widely used on the PC compatible platform. ... Windows redirects here. ... This article relates to both the original Classic Mac OS as well as Mac OS X, Apples more recent operating system. ... In computing, Bootstrapping refers to a process where a simple system activates another more complicated system that serves the same purpose. ... API and Api redirect here. ... A virtual file system (VFS) or virtual filesystem switch is an abstraction layer on top of a more concrete file system. ... A computer network is an interconnection of a group of computers. ... GUI redirects here. ... The history of computer operating systems recapitulates to a degree, the recent history of computing. ... A hardware abstraction layer (HAL) is an abstraction layer, implemented in software, between the physical hardware of a computer and the software that runs on that computer. ... For other uses, see System (disambiguation). ... Systems science is the science of complex systems. ... For other uses, see System (disambiguation). ... An example of a system: The nervous system. ... There are many definitions of complexity, therefore many natural, artificial and abstract objects or networks can be considered to be complex systems, and their study (complexity science) is highly interdisciplinary. ... Complex adaptive systems are special cases of complex systems. ... A conceptual system is a system that is comprised of non-physical objects, i. ... Cultural system refers to the functional interaction between the different elements of culture in a particular manner. ... The Lorenz attractor is an example of a non-linear dynamical system. ... An economic system is a particular set of social institutions which deals with the production, distribution and consumption of goods and services in a particular society. ... For other uses, see Ecological Systems Theory. ... In logic and mathematics, a formal system consists of two components, a formal language plus a set of inference rules or transformation rules. ... GPS redirects here. ... List of bones of the human skeleton Human anatomy is primarily the scientific study of the morphology of the adult human body. ... It has been suggested that this article or section be merged with Information systems. ... World distribution of major legal traditions The three major legal systems of the world today consist of civil law, common law and religious law. ... A system of measurement is a set of units which can be used to specify anything which can be measured and were historically important, regulated and defined because of trade and internal commerce. ... The International System of Units (symbol: SI) (for the French phrase Syst me International dUnit s) is the most widely used system of units. ... A multi-agent system (MAS) is a system composed of several software agents, collectively capable of reaching goals that are difficult to achieve by an individual agent or monolithic system. ... The nervous system is a highly specialized network whose principal components are nerves called neurons. ... In mathematics, a nonlinear system is one whose behavior cant be expressed as a sum of the behaviors of its parts (or of their multiples. ... A physical system is a system that is comprised of matter and energy. ... A political system is a system of politics and government. ... The human eye is the first element of a sensory system: in this case, vision, for the visual system. ... See Social structure of the United States for an explanation of concepts exsistance within US society. ... This article is about the Solar System. ... For other uses, see Chaos Theory (disambiguation). ... Complex systems have a number of properties, some of which are listed below. ... For control theory in psychology and sociology, see control theory (sociology). ... For other uses, see Cybernetics (disambiguation). ... Holism in science, or Holistic science, is an approach to research that emphasizes the study of complex systems. ... Sociotechnical systems theory is theory about the social aspects of people and society and technical aspects of machines and technology. ... Systems biology is a term used very widely in the biosciences, particularly from the year 2000 onwards, and in a variety of contexts. ... System dynamics is an approach to understanding the behaviour of complex systems over time. ... Systems Ecology is a transdiscipline which studies ecological systems, or ecosystems. ... Systems engineering techniques are used in complex projects: from spacecrafts to chip design, from robotics to creating large software products to building bridges, Systems engineering uses a host of tools that include modeling & simulation, requirements analysis, and scheduling to manage complexity Systems Engineering (SE) is an interdisciplinary approach and means... Systems science is the science of complex systems. ... Systems theory is an interdisciplinary field of science. ... Russell Lincoln Ackoff (born 12 February 1919) is a Professor Emeritus of the Wharton School in operations research and systems theory. ... William Ross Ashby (September 6, 1903, London, England - November 15, 1972) was a British psychiatrist and a pioneer in the study of complex systems. ... Gregory Bateson (9 May 1904–4 July 1980) was a British anthropologist, social scientist, linguist and cyberneticist whose work intersected that of many other fields. ... Anthony Stafford Beer (September 25, 1926 - August 23, 2002) was a theorist in operational research and management cybernetics. ... Karl Ludwig von Bertalanffy (September 19, 1901, Vienna, Austria - June 12, 1972, New York, USA) was a biologist who was a founder of general systems theory--which he literally translated from the mathematization of Nicolai Hartmanns Ontology as stated by himself in his seminal work-- .An Austrian citizen, he... Kenneth E. Boulding Kenneth Ewart Boulding (January 18, 1910 - March 18, 1993) was an economist, educator, peace activist, poet, religious mystic, devoted Quaker, systems scientist, and interdisciplinary philosopher. ... British academic Peter Checkland is the developer of soft-systems methodology (SSM) in the field of systems thinking. ... Charles West Churchman (born August 29, 1913 Philadelphia, Pennsylvania, died March 21, 2004 Bolinas, California) was an American philospher in the field of management science, operations research and systems theory. ... He is a twat He was born in Vienna and died in Pescadero, California. ... Charles François is a Belgian citizen, born 1922 and retired from the Belgian Foreign Service since 1987. ... Jay Wright Forrester (born 14 July 1918 Climax, Nebraska) is an American pioneer of computer engineering. ... Ralph Waldo Gerard (7 October 1900, Harvey, Illinois - 17 February 1974) was an American neurophysiologist and behavioral scientist known for his wide-ranging work on the nervous system, nerve metabolism, psychopharmacology, and biological bases of schizophrenia [1]. // Gerard was born in Harvey, Illinois at the beginning of the 20th century. ... Debora Hammond down the Green River in Canyonlands National Park Debora Hammond is an American systems theorist, working as an Associate Professor professor Interdisciplinary Studies of the Hutchins School of Liberal Studies at the Sonoma State University. ... George Jiri Klir (1932 Prague, Czechoslovakia) is an Czech-American computer scientist and professor of systems sciences at the Center for Intelligent Systems at the Binghamton University in New York. ... Niklas Luhmann (December 8, 1927 - November 6, 1998) was a German sociologist, administration expert, and social systems theorist, as well as one the most prominent modern day thinkers in the sociological systems theory. ... Humberto Maturana (born September 14, 1928 in Santiago) is a Chilean biologist whose work crosses over into philosophy and cognitive science. ... Donella Dana Meadows (March 13, 1941 Elgin, Illinois, USA - February 20, 2001, New Hampshire) was a pioneering environmental scientist, a teacher and writer. ... Mihajlo D. Mesarovic (1928) is a Yugoslavian scientist, who was professor of Systems Engineering and Mathematics at Case Western Reserve University. ... Howard Thomas Odum (1924-2002), commonly known as H.T. Odum or Tom Odum, was an eminent American ecosystem ecologist and a professor at the University of Florida. ... Talcott Parsons Talcott Edgar Frederick Parsons (December 13, 1902–May 8, 1979) was for many years the best-known sociologist in the United States, and indeed one of the best-known in the world. ... Ilya Prigogine (January 25, 1917 – May 28, 2003) was a Belgian physicist and chemist noted for his work on dissipative structures, complex systems, and irreversibility. ... Anatol Rapoport (born May 22, 1911) is a Russian-born American Jewish, mathematical psychologist. ... Francisco Varela (Santiago, September 7, 1946 – May 28, 2001, Paris) was a Chilean biologist and philosopher who, together with his teacher Humberto Maturana, is best known for introducing the concept of autopoiesis to biology. ... JOHN N. WARFIELD The career of John Warfield has been described as passing through four phases: Phase 1: Electrical engineering faculty member: 1948-1965 Phase 2: Starting a systems science research career path: 1966-1980 Phase 3: Accruing evidence and developing components of systems science: 1980-2000 Phase 4: Aggregating... Norbert Wiener Norbert Wiener (November 26, 1894, Columbia, Missouri – March 18, 1964, Stockholm Sweden) was an American theoretical and applied mathematician. ...


  Results from FactBites:
 
Server Operating Systems Technical Comparison (0 words)
For non-technical persons: A general overview of operating systems for non-technical people is located at: kinds of operating systems.
Brief summaries of operating systems are located at: summaries of operating systems.
The holistic area looks at operating systems from a holistic point of view and particular subjects in that presentation may be useful for comparison.
Howstuffworks "How Operating Systems Work" (4254 words)
The operating system must make sure that the requirements of the various users are balanced, and that each of the programs they are using has sufficient and separate resources so that a problem with one user doesn't affect the entire community of users.
Managing all the resources of the computer system is a large part of the operating system's function and, in the case of real-time operating systems, may be virtually all the functionality required.
For other operating systems, though, providing a relatively simple, consistent way for applications and humans to use the power of the hardware is a crucial part of their reason for existing.
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