All of kernel memory and user process memory is stored in physical memory in the computer (or perhaps on disk if data has been swapped from memory).

Someone says it is stored in RAM while other says it is on the hard disk. But since it is volatile, as soon as computer is turned off, the data stored in the RAM lose. So in computers, Operating System is installed and stored on the hard disk. As hard disk is a non volatile memory, OS does not lose on the turn off.

A computer is a machine composed of hardware and software components. A computer receives data through an input unit based on the instructions it is given and after it processes the data, it sends it back through an output device. To better imagine how a computer works, knowing what’s inside will make it easier.

Data management refers to several levels of managing data. From bottom to top, they are: (1) The part of the operating system that manages the physical storage and retrieval of data on a disk or other device.

The main components of an OS mainly include kernel, API or application program interface, user interface & file system, hardware devices and device drivers.

The hard drive (sometimes called the hard disk) is the main storage device in your computer. Like RAM, it can be added to and changed, and like ROM it is non-volatile, but it is slow. If you have files and folders on your computer, are stored on the hard drive. The operating system is also stored on the hard drive.

Input devices accept data in a form that the computer can use; they then send the data to the processing unit. The processor, more formally known as the central processing unit (CPU), has the electronic circuitry that manipulates input data into the information people want.

An operating system has three main functions: (1) manage the computer’s resources, such as the central processing unit, memory, disk drives, and printers, (2) establish a user interface, and (3) execute and provide services for applications software.

Types of Operating Systems

• Batch OS.
• Distributed OS.
• Multitasking OS.
• Network OS.
• Real-OS.
• Mobile OS.

The 4 basic elements of any top-level computer are:

• Processor.
• I/O Modules.
• Main Memory.
• System Bus.