(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 that use facilities provided by the kernel to perform higher-level housekeeping 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 removable operating system such as RISC OS.
The facilities and operating system provide 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.
