The operating system is system software that is stored on the storage device such as hard disk, CD-ROM, floppy disk (or in ROM). When a computer is switched on, the operating system is transferred from the storage device into main memory through ROM program. The handheld devices have the entire operating system in the ROM. This type of operating system is difficult to update.
An operating system controls and co-ordinates the overall operations of the computer system. It manages the computer hardware, controls the execution of application programs and provides the set of services to the users. The operating system acts as an interface between user and the computer. The users interact with the operating system indirectly through application program. Operating system manages all the operations of the computer and performs basic tasks such as;
- Accepts input from input devices.
- Sends output to output devices.
- Manages the application programs in memory.
- Manages the files on the storage devices.
- Manages & controls the I/O devices etc.
The operating system is responsible for managing hardware resources. An application program cannot access input/output devices or execute program instructions itself. The operating system performs these tasks through CPU on behalf of application programs. The operating system acts as a platform on which various application programs are executed. The user requests the application program to perform a particular task and the application program refers the request of user to operating system. Figure below shows the actual position of an operating in a computer system.
Usually, operating system is divided into two parts;
i) Resident part: This part of operating system is known as kernel. It contains the critical, functions. It is loaded into the main memory during the booting process of computer. It performs various functions residing in the main memory. The kernel will be discussed in the next topic.
ii) Non-resident part: This part of operating system is loaded into main memory when required.
The Examples of operating systems are:
- Disk Operating System (DOS) developed by Microsoft.
- Operating System 2 (QS/2) developed by IBM.
- XENIX or ZENIX developed by Microsoft.
- WTNOWS developed by Microsoft and also WINDOWS- NE Now-a- days, the most popular operating system is Windows operating system.
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