1. Age of Mechanical calculators:-
Abacus-It was the earliest counting device which was discovered in China. It could only add and subtract.
John Napier and his rods-
Scottish mathematician John Napier invented a principle of calculation called logarithm in 1614 and based on same principle, he invented Napier’s Bone in 1617 which could do multiplication faster.
English mathematician William Aughterd discovered a device with two rulers for calculation, which was also based on Napier’s principle in 1620, called Slide Rule. This could perform multiplication and division and was the first analog device.
French mathematician Blaise Pascal made the first mechanical calculator in1642 called Pascal’s computer, which can do addition and subtraction up to 8 digits. Pascal’s calculator had some cogs and gears rotating in compliment to each other.
German mathematician G.V. Leibniz modified the Pascal’s calculator and used the same principle to invent his new machine called Stepped Reckoner in 1671 which could do addition, subtraction, multiplication, division and also could find out square root.
Jacquard’s Loom and Punch Cards-
Joseph Marie Jacquard who was known as the “father of punch card” discovered a mechanism for automated weaving of clothes in 1802,which was based on a principle of present and absence of some holes in which later, principle of punch cards were developed.
He developed two electromechanical calculations called Difference engine(1822)and Analytical Engine(1833)which was a big achievement in the history of computer. He has also invented the working principle of computers, So he is also know as “father of computer”.
Lady Augusta Ada Lovelace-
She was a follower of Babbage and was first to Babbage to use binary system in his machine. And she was the “first programmer”.
A mathematician George Boole studied and presented the symbolic logics called “Boolean Algebra” which are the foundation of modern computers. This logic provided basic idea of presenting the electric circuits with binary input and output (0 or 1).
Dr. Herman Hollerith-
He was a census statician in US bureau of statics who invented a machine called Tabulating Machine ™ in 1886 which could process on the punch cards and perform census calculating faster than ever before. He established a company called International Business Machine (IBM) in 1923, which is the largest computer manufacturing company in this world till today.
2. Age of Electromechanical Computers:-
Based on Charles Babbage’s principle after 100 years of his death, prof. Howard Aiken developed the first electromechanical computer in 1937 called Mark-I. It was very huge (51x8x3 cubic feet),technically very complicated ,consumed a lot of electricity, generated a lot of heat, it was the milestone in the history of computer. It used 18000 vacuum tubes (valves) as a main memory device. Howard Aiken modified Mark-I and invented Mark-II in 1944, which used 19000 valves.
Atanasoff Berry Computer (ABC) was the first electronic digital computer. ABC was invented by J.V. Antanasoff and Clifford Berry in 1939-1942.It used 18000 valves and other 45 valves for internal logic and capacitors for storage of electrical charges. It used punch cards as secondary storage.
3. Age of Electronic Computers:-
John W. Mauchly and J.Presper Eckert invented Electronic Numerical Integrator And Calculator (ENIAC).At the time of it’s completion in 1946, ENIAC was the largest single electronic apparatus in the world. It was a large scale, general purpose digital electronic computer built from 17,468 vacuum tubes. There were two fundamental technical innovations in the ENIAC. The first had to do with combining different technical and design ideas into a single system that could perform 5000 additions and 300 multiplications per second. Although ENIAC was slow by today’s standards current microprocessors perform 100 million additions per second-this was two to three orders of magnitude (100 to 1000 times) faster than existing mechanical computers or calculators. It was the first and last computer which used decimal number system instead of binary system. The sheer speed of the machine and it’s programming mechanisms allowed the ENIAC to demonstrate that electronic computing could be applied to some of the nations most pressing problems, such as the development of the hydrogen bomb.
John Von Neumann:
J.V. Neumann was a mathematician who discovered a principle of stored program in 1945.So he is called the “father of stored program”. Before his principle, programs required for the computers were integrated and written permanently in chips. So modification of program was not possible. But after Neumann such programs were stored inside computer in some storage media, so modification was easy and flexible.
Maurice Wilkes invented Electronic Delay Storage Automatic Computer (EDSAC) in 1949.It also used vacuum tubes. It was the first stored program computer.
Electronic Discrete Variable Automatic Computer (EDVAC) was developed by J.P.Eckert and J.Mauchly in 1952.It also used vacuum tubes and some internal storage.
J.P. Eckert and J.Mauchly in 1961 developed Universal Automatic Computer (UNIVAC) which was the first computer manufactured for commercial use and general purpose digital computer.