OS introduction

Before get in to the details of operating system i clarify, What is operating system, and its responsibilities.

Basically an operating system is an resource allocator. Consider an example in our daily life: You are having telephonic call, at the same time bell is ringing. Now at this moment you have to decide which task to do first. Here your allocating the time to each task. Simply to say sharing the time between different processes(Tasks).

Similarly operating system is a resource allocator in the system. Now we look at what are the resources present in the system.

1. Central processing Unit(CPU)
2. Main memory
3. Secondary memory
4. Input&output devices(I/O dev's)

=>CPU is an most important unit in the system. Its responsbility is to execution of instructions present in the main memory. It doesn't have direct access to secondary memory.

=>Main memory is the one where executable code is placed to execute. Generally executable files are placed in secondary memory. when CPU is ready to execute then the code is bring to the main memory and then start executing.

=> Secondary memory is an auxiliary memory which is an low speed & low cost memory. Note accessing main memory and secondary memory are totally different

=> I/O devices are used for user to write data, read data from the system. Keyboard is an example for input device and printer is an example for output device.

Operating systems responsibility is to manage all the above resource to different users at the same time to utilize them optimally.