The most important program that runs on a computer. Every general-purpose computer must have an operating system to run other programs. Operating systems perform basic tasks, such as recognizing input from the keyboard, sending output to the display screen, keeping track of files and directories on the disk, and controlling peripheral devices such as disk drives and printers.
For large systems, the operating system has even greater responsibilities and powers. It is like a traffic cop -- it makes sure that different programs and users running at the same time do not interfere with each other. The operating system is also responsible for security, ensuring that unauthorized users do not access the system.
Operating systems provide a software platform on top of which other programs, called application programs, can run. The application programs must be written to run on top of a particular operating system. Your choice of operating system, therefore, determines to a great extent the applications you can run. For PCs, the most popular operating systems are DOS, OS/2, and Windows, but others are available, such as Linux.
As a user, you normally interact with the operating system through a set of commands. For example, the DOS operating system contains commands such as COPY and RENAME for copying files and changing the names of files, respectively. The commands are accepted and executed by a part of the operating system called the command processor or command line interpreter. Graphical user interfaces allow you to enter commands by pointing and clicking at objects that appear on the screen.
A family of operating systems for personal computers. Windows dominates the personal computer world, running, by some estimates, on 90% of all personal computers. The remaining 10% are mostly Macintosh computers. Like the Macintosh operating environment, Windows provides a graphical user interface (GUI), virtual memory management, multitasking, and support for many peripheral devices.
Windows History:
1985 : Windows 1.01
1986 : Windows 1.03
1987 : Windows 2.03
1988 : Windows 2.1
1990 : Windows 3.0
1992 : Windows 3.1
1992 : Windows For Workgroups 3.1
1993 : Microsoft Bob
1993 : Windows NT 3.1
1993 : Windows For Workgroups 3.11
1994 : Windows NT 3.5
1994 : Windows NT 3.51
1995 : Windows 95
1996 : Windows NT 4.0
1998 : Windows 98
2000 : Windows 2000
2000 : Windows ME
2001 : Windows XP
2006 : Windows Vista
2010 : Windows 7
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