What are the three major functions of an operating system?
• To manage the hardware Computers have peripheral devices (tape drives, disk drives, keyboards, modems, printers, etc.), so when services from one or more of these are required, the operating system makes sure that they are healthy and available. In a multi-user computing system (such as UNIX) the operating system is responsible for arbitrating requests for hardware from different users, so that everybody gets a fair chance at using the equipment. (For example, suppose that a system had four tape drives and two individual users each wanted three tape drives at the same time. The operating system has to make sure that one user doesn’t just grab and hold the drives without letting the other user have a chance, and it must insure that both users don’t grab two drives and lock each other out from the third.) • To provide a user interface Whether it is a GUI (graphical user interface) such as the Mac or one of the varieties of Windows, or a CLI (command line interface) such as DOS or UNIX,
