An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs.

(operating systems)

<operating system> (OS) The low-level software which handles the interface to peripheral hardware, schedules tasks, allocates storage, and presents a default interface to the user when no application program is running. The OS may be split into a kernel which is always present and various system programs which use facilities provided by the kernel to perform higher-level house-keeping tasks, often acting as servers in a client-server relationship. Some would include a graphical user interface and {window system} as part of the OS, others would not. The {operating system loader}, BIOS, or other firmware required at {boot time} or when installing the operating system would generally not be considered part of the operating system, though this distinction is unclear in the case of a {rommable operating system} such as RISC OS. The facilities an operating system provides and its general design philosophy exert an extremely strong influence on programming style and on the technical cultures that grow up around the machines on which it runs. Example operating systems include 386BSD, AIX, AOS, Amoeba, Angel, Artemis microkernel, BeOS, Brazil, COS, CP/M, CTSS, Chorus, DACNOS, DOSEXEC 2, GCOS, GEORGE 3, GEOS, ITS, KAOS, Linux, LynxOS, MPV, MS-DOS, MVS, Mach, Macintosh operating system, Microsoft Windows, MINIX, Multics, Multipop-68, Novell NetWare, OS-9, OS/2, Pick, Plan 9, QNX, RISC OS, STING, System V, System/360, TOPS-10, TOPS-20, TRUSIX, TWENEX, TYMCOM-X, Thoth, Unix, VM/CMS, VMS, VRTX, VSTa, VxWorks, WAITS. {FAQ (ftp://src.doc.ic.ac.uk/usenet/news-info/comp.os.research)}. Usenet newsgroup: news:comp.os.research. [Jargon File] (1999-06-09)

The development of a hobbyist operating system is one of the more involved and technical options for a computer hobbyist.

<operating system> (Mac OS) Apple Computer, Inc.'s proprietary operating system for their Macintosh family of personal computers. The part of the operating system that simulates the desktop is called "Finder." The multitasking version of Finder was called "MultiFinder" until multitasking was integrated into the core of the OS with the introduction of System 7.0 in 1990. The Macintosh series provides a built-in graphics language, called "QuickDraw", which provides a standard for software developers. Mac OS 8, scheduled for delivery in July 1997, included new human-interface features, increased system stability and performance, a PowerPC processor-native Finder, tighter integration of Internet access through panel-based "assistants," Personal Web Sharing and the ability to run Java applets and programs through Mac OS Run Time for Java. Version 9.2 was the last version of the bespoke Mac OS. The next version, Mac OS X is quite different, being based on Unix. See also Macintosh file system, Macintosh user interface. (2007-03-15)

The family of Macintosh operating systems developed by Apple Inc. includes the graphical user interface-based operating systems it has designed for use with its Macintosh series of personal computers since 1984, as well as the related system software it once created for compatible third-party systems.

DNOS or Dell Networking Operating System is a network operating system running on switches from Dell Networking. It is derived from either the PowerConnect OS (DNOS 6.

<operating system> (DOS) The name of a number of {operating systems} which include facilities for storing files on disk, often used to refer to Microsoft DOS. Such a system must handle physical disk I/O, the mapping of file names to disk addresses and protection of files from unauthorised access (in a multi-user system). A DOS should present a uniform interface to different storage device such as floppy disks, hard disks and {magnetic tape} drives. It may also provide some kind of locking to prevent unintentional simultaneous access by two processes to the same file (or record). (1998-07-08)