Any kind of operating system has to carry out a variety of functions fundamentally an operating system is to:
• Transfer input from the keyboard to memory
• Display messages, be it input or output on the screen
• Store data or programs in external storage devices
• Output data on the printer from the memory
• Control the printer and other peripherals
• Load programs and packages from storage and media to the main memory
• Copy data or programs from one device to another
• Communicate, control and provide error message giving the status of peripherals and processes
• Execute user programs and commands
• Protect working storage from overwriting by another program
• Store details of data and location stored for all media and devices
• Security and protection to the user data program and files.
The functions and much more in the case of multiuser systems can be grouped and classified as:
1. Processor management and Scheduling
2. Device management
3. File and data management
4. Memory management
5. Handling Users
6. User Commands execution
7. Job accounting and log maintenance
8. Security
9. Communication
10. Fault tolerance management
