First generation(1940’s): The earliest computers had no operating systems. There were no programming languages. Machines of the time were pure mechanical. They introduced Vacuum tubes in first time.

Second generation(1950’s): The routine had improved somewhat with the introduction of punch cards and batch system. They introduced Transistors and Batch Systems. The basic physical layout of batch system:
                             
 

Third generation(1960’s): Operating system designer developed concept of multiprogramming as used in spooling batch system. Another feature present in this generation was time-sharing technique, that is a variant of multiprogramming technique. They introduced ICs and Multiprogramming.

Fourth generation(1970’s-present): LSI(large scale integration) circuits, chips, operating system entered in the personal computer and the workstation age. MS-DOS and UNIX were introduced in this stage.They introduced Operating System for Personal Computers.

Real time, Embedded, parallel, Network programming were introduced between 1980-2000. Today's, we have parallel computer architectures(2000-present) and high speed operating systems.
 

Fifth generation(1990’s-present): In era Operating System for Mobile Computers invented.