Early Computing

The origins of the computer lie in the development of large mechanical calculating machines from the early nineteenth century. The English mathematician Charles Babbage is considered to have invented the concept of the programmable computer when he devised his Analytical Engine, which was never completed. Babbage’s idea of storing instructions on punched cards was adopted with commercial success by the American inventor Herman Hollerith. Hollerith’s first punch-card data-processing machine was developed specifically for tabulating U.S. census returns in 1890. From 1896, Hollerith’s company, the Tabulating Machine Company (which later became part of the International Business Machines Corporation), built similar machines for a range of uses.

While punched-card calculating machines proved an effective means of speeding up lengthy tabulations, they were not suitable for carrying out more complex mathematical tasks, such as differential equations. In 1876, the Irish physicist Sir William Thomson (later Lord Kelvin) put forward the concept of a mechanical differential analyzer for solving differential equations. However, as with Babbage, Thomson’s ideas were too advanced for contemporary engineering capabilities. The idea of the differential analyzer resurfaced in the 1930s. In the mid-1920s, the American scientist and electrical engineer Vannevar Bush began work on a mechanical-electrical differential analyzer, which he called the product integraph. As the product integraph could only solve the simplest differential equations, in 1930 Bush began to develop a more complex differential analyzer that could handle eighteen independent variables.

The leading European computing pioneers of the 1930s included Douglas Hartree, who constructed the first British differential analyzer, and Konrad Zuse, a German engineer who built the first binary calculator, fed by a punched-tape reader, in 1938. The significance of Zuse’s work is that it laid the foundations for digital computing. Earlier mechanical and electromechanical calculating machines were analogue computers, meaning that each of their components yielded a range of values, which combined to produce a result. Zuse’s binary calculator was based on the binary algebraic method of the nineteenth-century English mathematician George Boole, who demonstrated that equations could be reduced to a series of true or false propositions. This is known as Boolean logic, and in binary code the values of 0 and 1 are used to represent false and true. The advantages of the binary system became more apparent when electronic computers were developed in the late 1940s. The binary system lends itself perfectly to circuits where the state at any point depends on the presence or absence of a pulse of current or the low or high voltage of a component. A long series of bivalue electronic transactions is much simpler to engineer reliably and much more flexible in terms of program routines than fewer transactions with many possible values. In 1939, John V. Atanasoff and Clifford Berry of Iowa State University built the world’s first electronic calculator, which had an external magnetic drum to store a binary code program.