Opperating systems software

Operating Systems
The operating system is software that manages every part of a computer system—all hardware and all other software. To be specific, it controls every file, every device, every section of main memory, every nanosecond of processing time, and every network connection. It controls who can use the system and how. In short, it is the boss—without it, nothing can happen.

When a computer user sends a command by typing it from the keyboard or clicking with the mouse, the operating system must make sure that the command is executed. If it is not executed, the operating system must arrange for the user to receive a message, usually on the monitor, explaining


Platform Operating System
Microcomputers Linux, Macintosh OS, MS-DOS, Windows 98, Windows 2000
Minicomputers Linux, OpenVMS Alpha, UNIX
Mainframe computers IBM OS/390, IBM OS/400, UNIX
Supercomputers IRIX, UNICOS
Workstations HP-UX, Sun Solaris, UNIX
Networks Novell NetWare, UNIX, Windows NT, Windows 2000
Handheld computers Microsoft CE, Palm OS
the error. This does not necessarily mean that the operating system executes the command or sends the error message, but it does control the parts of the system that do.

Every operating system, regardless of its size and complexity, can be represented by a pyramid showing how its five major functions (called managers) work together. The memory manager, the processor manager, the device manager, and the file manager form the pyramid's base; network operating systems add a network manager as well. The user interface —the part of the operating system that communicates with the user—is supported by the other four or five managers.