An Encyclopedia of the History of Technology part 73. This one of a kind encyclopedia presents the entire field of technology from rudimentary agricultural tools to communication satellites in this first of its kind reference source. Following an introduction that discusses basic tools, devices, and mechanisms, the chapters are grouped into five parts that provide detailed information on materials, power and engineering, transportation, communication and calculation, and technology and society, revealing how different technologies have together evolved to produce enormous changes in the course of history | PART FOUR COMMUNICATION AND CALCULATION 1943 it used 1500 valves called vacuum tubes in the US . While not a stored-program machine Colossus may have been the world s first true automatic digital computer. Credit for this invention has become a matter of dispute much of the development work being hidden because of the Second World War. As early as 1931 Konrad Zuse in Germany had constructed a mechanical calculator using binary components. This Z1 was followed by a Z2 in 1939 but it was not until 1949 that he built the Z3 which used electromechanical relays. In the late 1930s DrJohn sought a device to perform mathematical calculations for twenty degree candidates at Iowa State College. Rejecting mechanical solutions he outlined ideas for memory and logic elements and built the first electronic digital computer with the assistance of Clifford Berry. It was called ABC Atanasoff-Berry-Computer. This very early vacuum tube system seems to have had no influence on subsequent developments but in 1974 a Federal judge ruled Dr Atanasoff the true inventor of the concepts required for a working digital computer. In 1937 George at the Bell Telephone Laboratories conceived a binary calculator using telephone relays with and other colleagues their Complex Computer was completed in 1939 and performed useful work at Bell Labs until 1949. Between 1939 and 1944 Harold of Harvard University with engineers of the International Business Machines Corporation built the electromechanical Automatic Sequence Controlled Calculator or Mark I. Between 1942 and 1946 the valve-based Electronic Numerator Integrator and Computer ENIAC was built at the Moore School of the University of Pennsylvania to compute ballistic tables for the US Army Ordnance Corps. This was followed by the Electronic Discrete Variable Automatic Computer EDVAC built between 1947 and 1950. Also starting about 1947 Eckert and John Mauchly of the Moore School conceived the
