History of Computer

History of Computer

Hi guys,

              This historical time-line covers the origins of the first mechanical and electronic computers.

 1.Mechanical Computer (1623-1945)

The idea of using machines to solve mathematical problems can be traced at least as far as the early 17th century.In 1642 Blaise Pascal (a famous French mathematician) invented an adding machine based on mechanical gears in which numbers were represented by the cogs on the wheels.This calculators that was capable of addition, subtraction, multiplication, and division.

                                 Englishman, Charles Babbage, invented in the 1830's a  "Difference Engine" made out of brass and pewter rods and gears, and also designed a further device which he called an "Analytical Engine". His design contained the five key characteristics of modern computers:-

   1) An input device

   2) Storage for numbers waiting to be processed

   3)A processor or number calculator

   4)A unit to control the task and the sequence of its calculations

   5) An output device

                                      In the time of Babbage there was a really high error rate in the calculation of math tables, so Babbage planned to find a solution to make it mechanical to remove the human error actor. His first shot at it was known as the Difference Engine. It was, theoretically, able to calculate polynomials by using a numerical method called the differences method. The government granted him a sum of money in 1823 to help with building it. Tragedy struck Babbage's life and halted work on the machine for a long period of time, during which Babbage traveled to clear his mind. After no progress being made on it and Babbage being unable to make it, the government officially abandoned the project in 1842. When Babbage was away from the difference engine, he began thinking of improved ways to make the engine, this one was called the Analytical Engine. The analytical engine used punched cards adapted from the Jacquard loom to specify input and the calculations to perform. The engine consisted of tow parts: the mill and the store. The mill, like a modern computer's CPU, executed the operations on values retrieved from the store, basically memory. The analytical engine was the world's first general-purpose computer.

2. Electronic Computers (1937-1953)

Three machines have been promoted at various times as the first electronic computers. These machines used electronic switches, in the form of vacuum tubes, instead of electromechanical relays. In principle the electronic switches would be more reliable, since they would have no moving parts that would wear out, but the technology was still new at that time and the tubes were comparable to relays in reliability. Electronic components had one major benefit, however: they could ``open'' and ``close'' about 1,000 times faster than mechanical switches.

                               The earliest attempt to build an electronic computer was by J.V.Atanasoff a professor of physics and mathematics at Iowa State,in 1937 Atanasoff set out to build a machine that would help his graduate students solve systems of partial differential equations. By 1941 he and graduate student Clifford Berry had succeeded in building a machine that could solve 29 simultaneous equations with 29 unknowns. However, the machine was not programmable, and was more of an electronic calculator.

                               A second early electronic machine was Colossus,designed by Alan Turing for the British military in 1943. This machine played an important role in breaking codes used by the German army in World War II. Turing's main contribution to the field of computer science was the idea of the Turing machine, a mathematical formalism widely used in the study of computable functions. The existence of Colossus was kept secret until long after the war ended, and the credit due to Turing and his colleagues for designing one of the first working electronic computers was slow in coming.

                                The first general purpose programmable electronic computer was the Electronic Numerical Integrator and Computer (ENIAC), built by J.Presper Eckert and John V.Mauchly at the University of Pennsylvania.

                                           Software technology during this period was very primitive. The first programs were written out in machine code, i.e. programmers directly wrote down the numbers that corresponded to the instructions they wanted to store in memory. By the 1950s programmers were using a symbolic notation, known as assembly language, then hand-translating the symbolic notation into machine code. Later programs known as assemblers performed the translation task.

                                           As primitive as they were, these first electronic machines were quite useful in   applied science and engineering. Atanasoff estimated that it would take eight hours to solve a set of equations with eight unknowns using a Marchant calculator, and 381 hours to solve 29 equations for 29 unknowns. The Atanasoff-Berry computer was able to complete the task in under an hour. The first problem run on the ENIAC, a numerical simulation used in the design of the hydrogen bomb, required 20 seconds, as opposed to forty hours using mechanical calculators.