The history of computing is a very fascinating subject and is told, partly or almost completely, in a number of books (see below for some suggestions).* It is about the human spirit as much as it is about the actual technology itself. In fact, what makes it interesting is how people with different backgrounds—the early pioneers coming from different disciplines—have often interacted and shared ideas with each other in order to produce hardware (followed by software) that eventually was used for building the various computing machines.
     The early computers were developed during, and shortly after, the Second World War. Many computer historians often point out that WWII was an ‘information’ (or a ‘scientific’) war, a war won partly (some would say chiefly) as a result of intelligence gathering, and rapid computer processing and code breaking that enabled crucial decisions to be made. At the start of WWII some American and British institutions were put on a war footing, with employees being trained to familiarise themselves with the emerging computing hardware. In the United States, for example, the Moore School of Electrical Engineering at the University of Pennsylvania started a special intensive 10-week course to train physicists and mathematicians for technical posts related to the war. (Two of these graduates were John W Mauchly and Arthur W Burks who became instructors and key players in the invention of the modern computer.) The main work at the Moore School was to produce “firing tables” for newly developed artillery. By 1942 the School was humming with computing activities which nonetheless still consisted of many human computers (including women) using desk calculating machines.
     At the Aberdeen Proving Ground (APG) in Maryland computing was done for ballistics; and when the war hostilities in Europe escalated, operations at the Ballistics Research Lab (BRL), located at the APG, increased in pace, many scientists having been brought over to work there. BRL served as a major Army centre for research and development in technologies related to weaponry, accelerator physics, and high-speed computing.
     The work at these two institutions and at others such as the Massachusetts Institute of Technology (MIT) and Harvard University, in addition to that being done at major office equipment manufacturers of the time (such as IBM) led to various computers being built in the US by 1950 (one such being the ENIAC, famous perhaps for not only being the first fully-electronic computing machine that could be reprogrammed but also for having been utilised to perform calculations related the hydrogen bomb, albeit when the war had already ended).
     In Britain, owing to the hardships of the war, a program of technological development matching that undertaken in the US was unfeasible, even though expertise in electronics and computing was already present (particularly at the Telecommunications Research Establishment in Malvern, and the British Post Office Labs at Dollis Hill in northwest London). Alan Turing, for example, published his famous ‘Entscheidungsproblem’ paper in 1936; and the Colossus had been built by British cryptologists at Bletchley Park by 1943. Following the war, British scientists visited the Moore School; and the free interchange of ideas between American and British scientists partly led to computer projects being undertaken in Manchester and Cambridge (at the respective universities) and at the National Physical Laboratories in Teddington. Before the close of the 1940s, several stored-program computers had been built both in the UK and the US.
     Of course, early computing developments were not only related to the war effort. Independent persons (and office machine companies) had already, by the late 1930s, experimented with the idea of a computer, or at least an automatic (‘programmable’) calculating machine. One such person was John Vincent Atanasoff who, together with Clifford Berry, worked on a project that in 1941 resulted in the building of a complete computer (which, incidentally, included several key concepts rediscovered years later). Others include the Frenchman Louis Couffignal, who—although did not build in collaboration with others a computer until the early 1950s—wrote several papers in the 1930s describing the design of an electromechanical calculator based on binary arithmetic; and Konrad Zuse, who in the same period built the electromechanical calculators called Z-1, Z-2, and Z-3. The Z-3, completed in 1941 was fully operational. A more ambitious design led to the Z-4, which was installed in a German V-2 rocket plant in 1945. (This survived the war and was leased to the Swiss Federal Polytechnic Institute in 1950, where it became the main computing facility for a research group in computers.)

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* Three ‘must-read’ books are Campbell-Kelly’s and Aspray’s Computer: A History of the Information Machine; Ceruzzi’s A History of Modern Computing; and Goldstein’s The Computer from Pascal to von Neumann. The first two texts, written by three leading computer historians and scientists, are general computer histories: they provide an in-depth narrative of the many early computer companies and the lives of those working in that industry. The third book, written by one of the first computer pioneers, traces the history of computation from the seventeenth century, moving quickly to a detailed (and sometimes technical) first-hand account of computer developments in the United States in the 1940s and 1950s. For a fairly comprehensive list of computer and ICT history-related books see the Bibliography section.