What is Operating System?

Definition and Goal:

            Operating System is a program / software that –

1)     Manages the computer hardware, and

2)     Provides user programs with simpler interfaces to the hardware.

 There are two main goals of the OS: First, convenience for users; and second efficient operation of the computer system.   

Components of the Computer System:

The computer system can be divided into four main components: Hardware, Operating System, Application Programs and Users.

The hardware comes at the lowest level. It contains physical devices such as processor, memory, keyboard, etc.

The next level is for the Operating System (OS). It manages all the underlying hardware and masks the complex details of hardware from the user. Thus, it provides simple interface between user programs and hardware.

Application programs perform particular tasks. Example of application programs includes airline reservation system, banking system, Web-browser, and many others. 

Users are at the top level. Users interact with the system by using application programs to perform particular tasks. 

 Function of Operating System:

ANS: The Main functions of operating system are:

Process Management:           Allocation of a CPU resources and scheduling.

Memory Management:          Allocation of memory and other storage of Program.

I/O Management:                  Device allocation and management.

File Management:                 Managing file systems, permissions of file, space allocation etc.

Other Sub Functions of Operating System:

Interpretation of commands and instructions

Command on compilers, assemblers utility programs etc

Database security, error detection

Maintain Login process on network

LAN / WAN Controlling. Transfer input from  the keyboard to memory.

Store data or program in external storage device.   

Control printer and other peripherals, execute user programs and commands.

 Evolution of Operating System:

Starting from beginning, computers and Operating Systems have evolved a lot. Very early, Charles Babbage, English mathematician, designed a true digital computer. He spent most of his life to get this machine properly worked. He remained unsuccessful. But, as an important outcome of his efforts, he realized the need of software. 

The First Generation (1945 - 1955)

Hardware:       vacuum tubes and plug boards.

Neumann and others succeeded in building Calculation engine.

No Operating Systems, No Programming languages.

Introduction of Punch cards.

The Second Generation (1955 - 1965)

Hardware:       Transistors

Clear separation between designers, builders, operators, programmers and maintenance personnel.

Machines were called mainframes.

Batch Operating System took birth.

The Third Generation (1965 - 1980)

Hardware:       Integrated Circuits (ICs)

Multiprogramming OS and variations of it such as Time sharing, Interactive, Multitasking OS come in picture.

SPOOLING (Simultaneous Peripheral Operation On Line) began during this time duration.

The Forth Generation (1980 - Present)

Hardware:       LSI (Large Scale Integration) circuits.

Personal Computers evolved.