4 generations of computers
the first generation of computers where in 1945-1955. they were made up of vacuum tubes and programmed using wiring plugboards. they were also very large. they were mostly used for numeral calculations.
1955-1965. this computer was a lot smaller and mainly used for scientific and enigineering applications. the mainframes were made up of transmitters
1965-1980. they were the first models which used multi-programmed batch processing. mainframes based on small ICs were used.
this is the most modern generation which was created in 1980 and is still used today. they have virtual machines and network computers