A computer actually is an electronic device capable of interpreting and executing programmed commands for input, processing, output and even the logical operations. And I would like to introduce the evolution of computer, and then talk about the generations of it.
During the ancient period, "Abacus" was probably the original mechanical counting device, and its effectiveness has withstood the test of time. Undoubtedly, it is still used to illustrate the principles of counting. Once again, that means the preceding of the computer is the mechanical device.
Blaise Pascal (1623-62) who was a French mathematician invented a "Pascaline" which was a first digital computer in 1642. It used gear-driven counting wheels to do addition. The numbers for each digital position were arranged on wheels so that a single revolution of one wheel resulted in one tenth of a revolution of the wheel to its immediate left.
Leibniz invented a computer built in 1694 that could add, and, after changing some things around, multiply.
English: Image of punched card of Herman Hollerith
The grave of Herman Hollerith, the punched-card pi...
Replica of early Hollerith punched card tabulator ...It was a special stepped gear mechanism for introducing the addend digits, and this is still being used. After that, Thomas created the first successful mechanical calculator that could add, subtract, multiply, and divide.
Then, Charles Babbage (1793-1871) who was a mathematics professor invented Babbage's Folly, the Difference Engine was capable of computing mathematical tables. The Analytical Engine could be powered by a locomotive engine and was capable of performing calculation automatically using preprogrammed instructions with correct sequence on punched cards written by Ada Byron (daughter of the great poet). In addition, the plans for this engine required an identical decimal computer operating on numbers of 50 decimal digits (or words) and having a storage capacity (memory) of 1,000 such digits.
Afterwards, the Punched card Tabulating Machine was invented in 1980. It was a mechanical computer using punched...