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EDVAC (''Electronic Discrete Variable Automatic Computer'') was one of the earliest electronic computers. Unlike its predecessor the ENIAC, it was binary rather than decimal, and was a stored program computer. ENIAC inventors John Mauchly and J. Presper Eckert proposed the EDVAC's construction in August 1944. A contract to build the new computer was signed in April 1946 with an initial budget of US$100,000. EDVAC was delivered to the Ballistics Research Laboratory in August 1949. Functionally, EDVAC was a binary serial computer with automatic addition, subtraction, multiplication, programmed division and automatic checking with an ultrasonic serial memory〔 capacity of 1,000 44-bit words. EDVAC's average addition time was 864 microseconds and its average multiplication time was 2,900 microseconds. By 1960 EDVAC was running over 20 hours a day with error-free run time averaging eight hours. EDVAC ran until 1961 when it was replaced by BRLESC. During its operational life it proved to be reliable and productive for its time. ==Project and plan== ENIAC inventors John Mauchly and J. Presper Eckert proposed the EDVAC's construction in August 1944, and design work for the EDVAC commenced before the ENIAC was fully operational. The design would implement a number of important architectural and logical improvements conceived during the ENIAC's construction and would incorporate a high-speed serial-access memory. Like the ENIAC, the EDVAC was built for the U.S. Army's Ballistics Research Laboratory at the Aberdeen Proving Ground by the University of Pennsylvania's Moore School of Electrical Engineering. Eckert and Mauchly and the other ENIAC designers were joined by John von Neumann in a consulting role; von Neumann summarized and discussed logical design developments in the 1945 ''First Draft of a Report on the EDVAC''.〔("First Draft of a Report on the EDVAC" ) (PDF format) by John von Neumann, Contract No.W-670-ORD-4926, between the United States Army Ordnance Department and the University of Pennsylvania. Moore School of Electrical Engineering, University of Pennsylvania, June 30, 1945. The report is also available in 〕 A contract to build the new computer was signed in April 1946 with an initial budget of US$100,000. The contract named the device the Electronic Discrete Variable Automatic Calculator. The final cost of EDVAC, however, was similar to the ENIAC's, at just under $500,000. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「EDVAC」の詳細全文を読む スポンサード リンク
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