Before go through the hard topics of operating system, you must have to learn about the basics of operating system such as what an operating system is, history of operating system, how operating system works, etc.
This tutorial will teach you about some basics of operating system.
Operating System is a layer of software that are basically a collection of programs that is used to keep track and use correctly all the computer components such as memory, printers, disks, keyboards, display, and network interfaces etc.
You can also say that the job operating system is to manage all these devices (computer devices) and provide user programs with a simpler interface to the hardware.
Operating system is the medium between the computer hardwares/components and users. Because without operating system, users can't communicate with those computer hardwares or computer components.
The placement of an operating system is shown in the figure given below, that comes above the hardware.
As you already known that to run computer hardwares or computer components or to use computer components, an operating system must required.
As you can see from the figure given above, hardware is at the bottom, which itself can be composed of two or more layers/levels. In it, the lowest level contains physical devices such as wires, power supplies, integrated circuit chips (IC chips), or cathode ray tubes (CRT), etc.
After this level or layer, micro-architecture is the next level. In this level, the physical devices are grouped together to form functional units.
Generally the micro-architecture level contains some registers internal to the CPU or Central Processing Unit and a data path containing an ALU or Arithmetical Logic Unit.
The next level is the Machine language, typically has between 50 and 300 instructions. In this level, the Input/Output devices are controlled by loading values into special device registers. For eg., a disk can be commanded to read by loading the values of disk address, main memory address, byte count, and direction into its register.
An operating system must be provided to hide all the complexity. Operating system hides all the hardware components and gives the programmer a more convenient set of instructions to work with.
Now in the next level (or on the top of operating system), is the rest of the system softwares and application softwares. All the application programs comes after the system programs.
Generally, application programs are purchased or may be written by a user or programmer to solver their particular problems.