An operating system is system software which may be viewed as an organized collection of software consisting of procedures for operating a computer and providing an environment for execution of programs. It acts as an interface between users and the hardware of a computer system. There are many important reasons for studying operating systems. Some of them are:
1) User interacts with computer through the operating system in order to accomplish his/her task since it is his/her primary interface with a computer.
2) It helps users to understand the inner functions of a computer very closely.
3) Many concepts and techniques found in the operating system have general applicability in other applications.
The introductory concepts of an operating system will be the main focus in this unit. The unit introduces several OS concept such as command interface, bootstrap loader, kernel, nanokernel, thin clients, multitasking and multiprogramming OS. To understand OS one needs to understand what kinds of services are provided by process management, I/O device management, memory management and file system. This topic is an important part of the unit. The end of unit goes into a brief history of evolution of OS, starting from serial processing, batch processing till date.