Engineers have continually worked on both hardware and software development since the invention of earlier counting tools to the achievieing of the first generation computers, to even latest computers.
This chronological improvement can then be discussed as in generations as listed below.
First generation computers.
They were developed between 1940s and 1958. They used thousands of electronic gadgets known as thermionic valves/ vaccume tubes as the principle of electronic generation.
Examples include UNIVAC & ENIAC.
These computers were very slow in operation, very expensive to buy, used a lot of power hence emitted much heat and so they required an extensive air condition. Used magnetic drums as mode of storage.
Second generation computers
developed between 1958 and 1964 with a solid state device called transistor as it’s principle of electronic generation which was smaller than it’s predecessor.
This lead to reduced power consumption by this computers hence emitting less heat and also reduced in physical size.
Computers in this period relied on punched cards for input and printouts for output.
Examples include UNIVAC 1107, Honey well 200, ATLAS LEO Mark III and IBM 7080.
Third generation computers
the aspect of development in technology led to the introduction of silicon chip called integrated circuit (I.C). They were developed between years 1964 – 1970.
It was for the purpose of reducing the amount of electricity that was to be consumed by the computer and relatively reduce the amount of heat that was to be produced and their physical size too.
Computers developed in this generation were faster, more reliable and did not require an extensive air conditioner. They used keyboard, monitor and interfaced with an operating system.
Examples include IBM 360 and ICL 19000 series.
Fourth generation circuit
here man basically focused on developing high speed computers in terms of processing speed.
The outcome was small size computers, fast, less heat emitting and more user friendly computers. Their development took place between 1970 and 1999.
They used a very large scale integrated circuit (VLS – IC)/ microprocessor. They supported graphical user interface ( GUI)
Fifth generation computers
can be termed to be the latest computers that can well converse with the user/ orgware. These computers have been developed since 1999 to present; they use magnetic core or microprocessor as a processing unit.
They have very high processing power compared to their predecessor; use less electricity, small in size, less expensive, produce less heat and more users friendly.
Computers in this generation have been characterised by artificial intelligence, connectivity to internet, superior hardware and software yet are small in size.
Hopefully soon we shall have computers with all human capabilities (of course without soul and blood) to work without human interventions nor aid. You could read more on androids and geminoids.