Operating system provides macro facility for programmers which allow them to define abbrivation for part of his program.The macro processor treats such definitions as individual code lines and save them as macro definition.So each abbrivation will be actually replaced by their value contents by macro processor.

Macro processor is responsible for substituting all macro calls or macro abbrivations with their macro values.

Operating system The most fundamental software run on a computer. All computers have an operating system, which is used among other things to start and run other programs. The operating system performs important tasks, such as receiving data from the keyboard and mouse, sending data to the screen, keeping files and folders under control and checking the various units in the machine (e.g. disks, printers etc). An operating system as a rule also contains a user interface, which for example enables the user to control the machine using graphic icons, windows and menus.

Open source first evolved during the 1970s. Richard Stallman, an American software developer who believes that Sharing source-code and ideas are fundamental to freedom of speech, developed a ‘free’ version of the widely used ‘Unix’ operating system. The resulting ‘GNU’ program was released under a specially created General Public License (‘GNU GPL’). This was designed to ensure that the source-code would remain openly available to all. It was not intended to prevent commercial usage or distribution.

This is list of common commands which can be used from command prompt or from run screen.You can just do:-

=>Click On Start menu

=>Click On Run

Type or paste any of command from list to test it or use it.Be sure to read description of command before using it and you will be runing command at your own risk :-) i will not there for fixing it if you got issues from these commands .However these are safe commands but still you must be able enough to know that what ar you doing.

IPCONFIG: This command is used to get information about your system’s network setup and configuration, or broadband internet connection, and details. The IPCONFIG command used by itself provides you with a concise list of the network interfaces on your system and their IP addresses.

This is a commonly-used network protocol. The X.25 protocol allows computers on different public networks (such as CompuServe, Tymnet, or a TCP/IP network) to communicate through an intermediary computer at the network layer level. X.25's protocols correspond closely to the data-link and physical-layer protocols defined in the Open Systems Interconnection (OSI) communication model.

Stand-alone computing systems
●Independent computers
●Independent tasks
Networked computing systems
●Interconnected independent computers
●Processes of independent tasks can communicate
Distributed computing systems
●Loosely-coupled computers
●Processes of individual tasks transparently share resources
Parallel computing systems
●Tightly-coupled processing units
●Several processes cooperate on a single task

During lifetime of process,it go through varius states of operations which are called mode or state of process.a operating system process can be in one of following state at a time:-