Editing EDVAC

{{Short description|Early computer}}
{{Use mdy dates|date=December 2021}}
[[File:Edvac.jpg|thumb|275px|The EDVAC as installed in Building 328 at the [[Ballistic Research Laboratory]]]]
'''EDVAC''' ('''Electronic Discrete Variable Automatic Computer''') was one of the earliest [[electronics|electronic]] [[computer]]s. It was built by [[Moore School of Electrical Engineering]] at the [[University of Pennsylvania]].<ref>{{Cite web|title=The History of Computing at BRL|url=http://chimera.roma1.infn.it/SPENG/COMMON/ftp.arl.mil/mike/comphist/hist.html|access-date=2021-12-03|website=chimera.roma1.infn.it}}</ref><ref name="EoCS2003" >{{Cite book|url=https://www.worldcat.org/oclc/436846454|title=Encyclopedia of computer science.|date=2003|publisher=Wiley|others=Edwin D. Reilly, Anthony Ralston, David Hemmendinger|isbn=978-1-84972-160-8|edition=4th|location=Chichester, Eng.|oclc=436846454}}</ref>{{Rp|pages=626–628}} Along with [[ORDVAC]], it was a successor to the [[ENIAC]]. Unlike ENIAC, it was [[binary numeral system|binary]] rather than [[decimal]], and was designed to be a [[stored-program computer]].  

ENIAC inventors, [[John Mauchly]] and [[J. Presper Eckert]], proposed the EDVAC's construction in August 1945.  A contract to build the new computer was signed in April 1946 with an initial budget of [[United States dollar|US$]]100,000. EDVAC was delivered to the [[Ballistic Research Laboratory]] in 1949. The [[Ballistic Research Laboratory]] became a part of the [[US Army Research Laboratory]] in 1952.

Functionally, EDVAC was a binary [[serial computer]] with automatic addition, subtraction, multiplication, programmed division and automatic checking with an [[delay-line memory|ultrasonic serial memory]]<ref name="Wilkes"/> having a capacity of 1,024 44-bit [[word (data type)|word]]s.  EDVAC's average addition time was 864 [[microsecond]]s and its average multiplication time was 2,900 microseconds.

==Project  and plan==
<!-- Deleted image removed: [[File:Screen Shot 2020-09-06 at 8.58.54 AM big.png|thumb|First page of  ''Automatic High-Speed Computing: A Progress Report on the EDVAC''. [[Computer History Museum]].]] -->
ENIAC inventors John Mauchly and J. Presper Eckert proposed EDVAC's construction in August 1944, and design work for EDVAC commenced before 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 [[Delay-line memory|serial-access memory]].<ref name=Wilkes>{{cite book | last=Wilkes | first=M. V. | author-link=Maurice Vincent Wilkes | title=Automatic Digital Computers | publisher=John Wiley & Sons | year=1956 | location=New York | pages=305 pages | id=QA76.W5 1956 }}</ref>  Like the ENIAC, the EDVAC was built for the [[United States Army|U.S. Army]]'s [[Ballistics Research Laboratory]] at the [[Aberdeen Proving Ground]] by the [[University of Pennsylvania]]'s [[Moore School of Electrical Engineering]].{{r|EoCS2003|pp=626–628}}  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]]'', written between February and June of that year.<ref>[http://www.virtualtravelog.net/entries/2003-08-TheFirstDraft.pdf "First Draft of a Report on the EDVAC"] {{Webarchive|url=https://web.archive.org/web/20040423232125/http://www.virtualtravelog.net/entries/2003-08-TheFirstDraft.pdf |date=2004-04-23 }} ([[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 {{cite book| first=Nancy| last=Stern| title=From ENIAC to UNIVAC: An Appraisal of the Eckert–Mauchly Computers| publisher=Digital Press| year=1981}}</ref><ref name="EDVAC Draft">{{cite web|url=https://www.historyofinformation.com/detail.php?entryid=806|title=The von Neumann Architecture|work=History of Information|access-date=November 29, 2024}}</ref> Later in September 1945, Eckert and Mauchly followed up with a progress report on automatic high-speed computing for the EDVAC.<ref name="EDVAC Report">{{cite web|url=https://www.historyofinformation.com/detail.php?id=3627|title=The First Engineering Report on the EDVAC|work=History of Information|access-date=November 29, 2024}}</ref>

In early 1946, months after the completion of ENIAC, the [[University of Pennsylvania]] adopted a new patent policy, which would have required Eckert and Mauchly to assign all their patents to the university if they stayed beyond spring of that year. Unable to reach an agreement with the university, the duo left the [[Moore School of Electrical Engineering]] in March 1946, along with many of the senior engineering staff. Simultaneously, the duo founded the Electronic Control Company (later renamed the [[Eckert-Mauchly Computer Corporation]]) in [[Philadelphia]].<ref>{{cite video|url=https://www.youtube.com/watch?v=bGk9W65vXNA|date=May 14, 2015|title=Computer History: ENIAC - The First Electronic Computer|author=Computer History Archives Project|work=[[YouTube]]|access-date=November 11, 2024|url-status=live}}</ref> A contract to build the new computer was signed in April 1946 with an initial budget of [[United States dollar|US$]]100,000. Later in August of that year, during the last of the [[Moore School Lectures]], the Moore School team members were proposing new technological designs for the computer and its [[stored program]] concept. 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.

The [[Raytheon Company]] was a subcontractor on EDVAC machines.<ref>{{Cite web |title=Raytheon Company {{!}} Selling the Computer Revolution {{!}} Computer History Museum |url=https://www.computerhistory.org/brochures/q-s/raytheon-company/ |access-date=2022-04-20 |website=www.computerhistory.org}}</ref>

==Technical description==
The EDVAC was a [[Bit-serial architecture|binary serial computer]] with automatic addition, subtraction, multiplication, programmed division and automatic checking with an ultrasonic serial memory<ref name="Wilkes"/> capacity of 1,024 44-bit words, thus giving a memory, in modern terms, of 5.6 [[kilobyte]]s.<ref>[http://ed-thelen.org/comp-hist/BRL61-e.html#EDVAC BRL report 1961]</ref>

Physically, the computer comprised the following components:
* a [[magnetic tape]] reader-recorder (Wilkes 1956:36<ref name="Wilkes"/> describes this as a [[Wire recording|wire recorder]].)
* a control unit with an [[oscilloscope]]
* a dispatcher unit to receive instructions from the control and memory and direct them to other units
* a computational unit to perform arithmetic operations on a pair of numbers and send the result to memory after checking on a duplicate unit
* a timer
* a dual memory unit consisting of two sets of 64 [[mercury (element)|mercury]] acoustic delay lines of eight words capacity on each line
* three temporary delay-line tanks each holding a single word<ref name="Wilkes"/>

EDVAC's average addition time was 864 microseconds (about 1,160&nbsp;operations per second) and its average multiplication time was 2,900 microseconds (about 340&nbsp;operations per second). Time for an operation depended on memory access time, which varied depending on the memory address and the current point in the serial memory's recirculation cycle.

The computer had 5,937 [[vacuum tube]]s and 12,000 [[diode]]s, and consumed 56 [[kilowatt|kW]] of power. It covered 490&nbsp;ft² (45.5 m<sup>2</sup>) of floor space and weighed {{Convert|17,300|lb|ST MT}}.<ref>{{Cite web|url=http://ed-thelen.org/comp-hist/BRL-e-h.html#EDVAC|title=EDVAC|last=Weik|first=Martin H.|date=December 1955|website=ed-thelen.org|series=A Survey of Domestic Electronic Digital Computing Systems}}</ref> The full complement of operating personnel was thirty people per eight-hour [[shift work|shift]].

EDVAC could also do [[floating-point arithmetic]].  It used 33 bits for the [[Significand|mantissa]] and one bit for its sign.  It used 10 bits for the power of 2, including the sign bit.

For executable instructions, the 44-bit word was divided into four 10-bit addresses and four bits to encode the index of an operation.  The first two addresses were to the numbers in memory being used in the operation, the third address was for the memory location to store the result, and the fourth address was the location of the next instruction to be executed.  Only 12 of the possible 16 instructions were used.

==Impact on future computer design==
John Von Neumann's famous EDVAC monograph, ''[[First Draft of a Report on the EDVAC]]'', proposed the main enhancement to its design that embodied the principal "stored-program" concept that we now call the [[Von Neumann architecture]].  This was the storing of the program in the same memory as the data. The British computers [[EDSAC]] at Cambridge and the [[Manchester Baby]] were the first working computers that followed this design, and it has been followed by the great majority of computers made since. Having the program and data in different memories is now called the [[Harvard architecture]] to distinguish it.

==Installation and operation==
EDVAC was delivered to the [[Ballistics Research Laboratory]] in 1949. After a number of problems had been discovered and solved, the computer began operation in 1951 although only on a limited basis.<ref name=":0" /><ref>{{Cite journal|date=April 1951|title=The EDVAC|url=http://www.dtic.mil/docs/citations/AD0694600|journal=Digital Computer Newsletter|language=en|volume=3|issue=1|pages=2}}{{dead link|date=June 2022|bot=medic}}{{cbignore|bot=medic}}</ref>

In 1952 (April/May), it was running over {{#expr:floor(341/(16+31)) round 0}} hours a day (period from 15 April to 31 May, used for 341 hours).<ref>{{Cite journal|date=July 1952|title=6. Aberdeen Proving Ground Computers: The EDVAC|url=http://www.dtic.mil/docs/citations/AD0694605|journal=Digital Computer Newsletter|language=en|volume=4|issue=3|pages=4}}{{dead link|date=June 2022|bot=medic}}{{cbignore|bot=medic}}</ref>

By 1957, EDVAC was running over 20 hours a day with error-free run time averaging 8 hours. EDVAC received a number of upgrades including [[punched card|punch-card]] I/O in 1954, extra memory in slower [[drum memory|magnetic drum]] form in 1955, and a [[floating-point arithmetic]] unit in 1958.

EDVAC ran until 1962<ref name=":0">{{Cite journal|last=Williams|first=Michael R.|date=1993|title=The origins, uses, and fate of the edvac|journal=IEEE Ann. Hist. Comput.|volume=15|issue=1|pages=30, 32–33, 36–37|citeseerx=10.1.1.705.4726|doi=10.1109/85.194089|s2cid=7842904 }}</ref> when it was replaced by [[BRLESC]].

==See also==
* [[List of vacuum-tube computers]]

==References==
{{Reflist}}

==External links==
* {{cite book | author=Moore School of Electrical Engineering | title=A Functional Description of the EDVAC: A Report of Development Work under Contract W36-034-ORD-7593 with the Ordnance Department, Department of the Army | series=Its Research Division Report50-9) | publisher=University of Pennsylvania | year=1949 | location=Philadelphia | url=http://catalog.hathitrust.org/Record/000472833 }} A complete technical description of EDVAC's original structure and operation in 1949; includes an errata dated 1950. Fully viewable online.
* [https://web.archive.org/web/20130607041151/http://conservancy.umn.edu/handle/107275 Oral history interview with J. Presper Eckert], [[Charles Babbage Institute]], University of Minnesota.
* [https://web.archive.org/web/20130617095142/http://conservancy.umn.edu/handle/107216 Oral history interview with Carl Chambers], [[Charles Babbage Institute]], University of Minnesota.
* [https://web.archive.org/web/20130617101503/http://conservancy.umn.edu/handle/107688 Oral history interview with Irven A. Travis], [[Charles Babbage Institute]], University of Minnesota.
* [https://web.archive.org/web/20130617102053/http://conservancy.umn.edu/handle/107704 Oral history interview with S. Reid Warren], [[Charles Babbage Institute]], University of Minnesota.
* [https://web.archive.org/web/20130617100515/http://conservancy.umn.edu/handle/107363 Oral history interview with Frances E. Holberton], [[Charles Babbage Institute]], University of Minnesota.
{{Authority control}}{{Mainframes}}
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[[Category:1940s computers]]
[[Category:Computer-related introductions in 1951]]
[[Category:One-of-a-kind computers]]
[[Category:Vacuum tube computers]]
[[Category:Serial computers]]