In the early days, basic computers were nothing but calculators. The abacus is an example. The ancient Greek-designed Antikythera mechanism, used for astronomical prediction, is considered as the world’s oldest analogue computer. Later, many models were developed like the astrolabe, the differential analyzer etc.
Charles Babbage, who is known as the father of computers, first conceptualized and invented the first mechanical computer in the early 19th century. He designed the Analytical Engine and it was this design that the framework of the computers of today are based on. The first modern analogue computer was invented by Sir William Thomson in 1872.
The first electronic digital computer was built by Dr. John. V. Atanasoff and Clifford Berry. The general purpose digital computer, the Electronic Numerical Integrator and Computer (ENIAC) was built in the 1940s.
Earlier computers were huge but the introduction of transistors reduced the size of computers, and made them portable.
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