Glenn A. Beck (background) andBetty Snyder (foreground) program ENIAC inBRL building 328. (U.S. Army photo,c. 1947–1955)
ENIAC (/ˈɛniæk/;Electronic Numerical Integrator and Computer)[1][2] was the firstprogrammable,electronic, general-purposedigital computer, completed in 1945.[3][4] Other computers had some of these features, but ENIAC was the first to have them all. It wasTuring-complete and able to solve "a large class of numerical problems" through reprogramming.[5][6]
ENIAC was completed in 1945 and first put to work for practical purposes on December 10, 1945.[11]
ENIAC was formally dedicated at theUniversity of Pennsylvania on February 15, 1946, having cost $487,000 (equivalent to $7,000,000 in 2024), and called a "Giant Brain" by the press.[12] It had a speed on the order of one thousand times faster than that ofelectro-mechanical machines.[13]
ENIAC was formally accepted by the U.S. Army Ordnance Corps in July 1946. It was transferred toAberdeen Proving Ground inAberdeen, Maryland in 1947, where it was in continuous operation until 1955.
ENIAC's design and construction was financed by the United States Army Ordnance Corps, Research and Development Command, led by Major GeneralGladeon M. Barnes. The total cost was about $487,000, equivalent to $7,000,000 in 2024.[14] The conception of ENIAC began in June 1941, whenFriden calculators anddifferential analyzers were used by theUnited States Army Ordnance Department to compute firing tables for artillery, which was done by graduate students under John Mauchly's supervision. Mauchly began to wonder if electronics could be applied to mathematics for faster calculations. He partnered with research associateJ. Presper Eckert, as Mauchly wasn't an electronics expert, to draft an electronic computer that could work at an excellent pace. Later, in August 1942, Mauchly proposed an all-electronic calculating machine that could help the U.S. Army calculate complex ballistics tables.[15][16][17] The U.S. Army Ordnance accepted their plan, giving theUniversity of Pennsylvania a six-months research contract for $61,700.[18] The construction contract was signed on June 5, 1943; work on the computer began in secret at theUniversity of Pennsylvania'sMoore School of Electrical Engineering[19] the following month, under the code name "Project PX", withJohn Grist Brainerd as principal investigator.Herman Goldstine persuaded the Army to fund the project, which put him in charge to oversee it for them.[20] Assembly of the computer began in June 1944.[18] Later, in September of that year, Eckert and Mauchly completed their conception of the computer.[21] Construction was complete in May 1945, and testing began at the Moore School. Later, in November of that year, the duo, along withJohn Brainerd andHerman Goldstine, issued the first confidentially published report on the computer, which describes how it functioned and the methods by which it was programmed.[16]
ENIAC was a large, modular computer, composed of individual panels to perform different functions. Twenty of these modules were accumulators that could not only add and subtract, but hold a ten-digitdecimal number in memory. Numbers were passed between these units across several general-purposebuses (ortrays, as they were called). In order to achieve its high speed, the panels had to send and receive numbers, compute, save the answer and trigger the next operation, all without any moving parts. Key to its versatility was the ability tobranch; it could trigger different operations, depending on the sign of a computed result.
By the end of its operation in 1956, ENIAC contained 18,000vacuum tubes, 7,200crystal diodes, 6,000relays, 70,000resistors, 10,000capacitors, and approximately 5,000,000 hand-soldered joints. It weighed more than 30short tons (27 t), was roughly 10 ft (3 m) tall, 3 ft (1 m) deep, and 100 ft (30 m) long, occupied 300 sq ft (28 m2)[25] and consumed 150 kW of electricity.[26][27] Input was possible from an IBMcard reader and an IBMcard punch was used for output. These cards could be used to produce printed output offline using anIBM accounting machine, such as theIBM 405. While ENIAC had no system to store memory in its inception, these punch cards could be used for external memory storage.[28] In 1953, a 100-wordmagnetic-core memory built by theBurroughs Corporation was added to ENIAC.[29]
ENIAC usedten-positionring counters to store digits; each digit required 36 vacuum tubes, 10 of which were the dual triodes making up theflip-flops of the ring counter. Arithmetic was performed by "counting" pulses with the ring counters and generating carry pulses if the counter "wrapped around", the idea being to electronically emulate the operation of the digit wheels of a mechanicaladding machine.[30]
ENIAC had 20 ten-digit signedaccumulators, which usedten's complement representation and could perform 5,000 simple addition or subtraction operations between any of them and a source (e.g., another accumulator or a constant transmitter) per second. It was possible to connect several accumulators to run simultaneously, so the peak speed of operation was potentially much higher, due to parallel operation.[31][32]
Cpl. Irwin Goldstein (foreground) sets the switches on one of ENIAC's function tables at the Moore School of Electrical Engineering. (U.S. Army photo, 1946)[33]
It was possible to wire the carry of one accumulator into another accumulator to perform arithmetic with double the precision, but the accumulator carry circuit timing prevented the wiring of three or more for even higher precision. ENIAC used four of the accumulators (controlled by a special multiplier unit) to perform up to 385 multiplication operations per second; five of the accumulators were controlled by a special divider/square-rooter unit to perform up to 40 division operations per second or threesquare root operations per second.
The other nine units in ENIAC were the initiating unit (started and stopped the machine), the cycling unit (used for synchronizing the other units), the master programmer (controlled loop sequencing), the reader (controlled an IBM punch-card reader), the printer (controlled an IBM card punch), the constant transmitter, and three function tables.[34][35]
The references by Rojas and Hashagen (or Wilkes)[22] give more details about the times for operations, which differ somewhat from those stated above.
The basic machine cycle was 200microseconds (20 cycles of the 100 kHz clock in the cycling unit), or 5,000 cycles per second for operations on the 10-digit numbers. In one of these cycles, ENIAC could write a number to a register, read a number from a register, or add/subtract two numbers.
A multiplication of a 10-digit number by ad-digit number (ford up to 10) tookd+4 cycles, so the multiplication of a 10-digit number by 10-digit number took 14 cycles, or 2,800 microseconds—a rate of 357 per second. If one of the numbers had fewer than 10 digits, the operation was faster.
Division and square roots took 13(d+1) cycles, whered is the number of digits in the result (quotient or square root). So a division or square root took up to 143 cycles, or 28,600 microseconds—a rate of 35 per second. (Wilkes 1956:20[22] states that a division with a 10-digit quotient required 6 milliseconds.) If the result had fewer than ten digits, it was obtained faster.
ENIAC used commonoctal-baseradio tubes of the day; the decimalaccumulators were made of6SN7flip-flops, while 6L7s, 6SJ7s, 6SA7s and 6AC7s were used in logic functions.[37] Numerous6L6s and6V6s served as line drivers to drive pulses through cables between rack assemblies.
Several tubes burned out almost every day, leaving ENIAC nonfunctional about half the time. Special high-reliability tubes were not available until 1948. Most of these failures, however, occurred during the warm-up and cool-down periods, when the tube heaters and cathodes were under the most thermal stress. Engineers reduced ENIAC's tube failures to the more acceptable rate of one tube every two days. According to an interview in 1989 with Eckert, "We had a tube fail about every two days and we could locate the problem within 15 minutes."[38]In 1954, the longest continuous period of operation without a failure was 116 hours—close to five days.
ENIAC could be programmed to perform complex sequences of operations, including loops, branches, and subroutines. However, instead of thestored-program computers that exist today, ENIAC was just a large collection of arithmetic machines, which originally had programs set up into the machine[39] by a combination ofplugboard wiring and three portable function tables (containing 1,200 ten-way switches each).[40] The task of taking a problem and mapping it onto the machine was complex, and usually took weeks. Due to the complexity of mapping programs onto the machine, programs were only changed after huge numbers of tests of the current program.[41] After the program was figured out on paper, the process of getting the program into ENIAC by manipulating its switches and cables could take days. This was followed by a period of verification and debugging, aided by the ability to execute the program step by step. A programming tutorial for the modulo function using an ENIAC simulator gives an impression of what a program on the ENIAC looked like.[42][43][44]
ENIAC's six primary programmers,Kay McNulty,Betty Jennings,Betty Snyder,Marlyn Wescoff,Fran Bilas andRuth Lichterman, not only determined how to input ENIAC programs, but also developed an understanding of ENIAC's inner workings.[45][46] The programmers were often able to narrow bugs down to an individual failed tube which could be pointed to for replacement by a technician.[47]
DuringWorld War II, while theU.S. Army needed to compute ballistics trajectories, many women were interviewed for this task. At least 200 women were hired by theMoore School of Engineering to work as "computers"[24] and six of them were chosen to be the programmers of ENIAC.Betty Holberton,Kay McNulty,Marlyn Wescoff,Ruth Lichterman,Betty Jean Jennings, andFran Bilas programmed the ENIAC to perform calculations for ballistics trajectories electronically for the Army'sBallistic Research Laboratory.[48] While men having the same education and experience were designated "professionals", these women were designated "subprofessionals", though they had professional degrees in mathematics and were highly trained mathematicians.[48]
These women were not "refrigerator ladies", i.e., models posing in front of the machine for press photography, as then computer scientist undergradKathryn Kleiman discovered in her own research as opposed to what she was told by a historian in computing.[49] However, some of the women did not receive recognition for their work on the ENIAC in their entire lifetimes.[24] After the war ended, the women continued to work on the ENIAC. Their expertise made their positions difficult to replace with returning soldiers.[50] Later in the 1990s, Kleiman learned that most of the ENIAC programmers were not invited to the ENIAC's 50th anniversary event. So she made it her mission to track them down and record their oral histories. "They were shocked to be discovered," Kleiman says. "They were thrilled to be recognized, but had mixed impressions about how they felt about being ignored for so long."[49] Kleiman released a book on the six female ENIAC programmers in 2022.[51]
These early programmers were drawn from a group of about two hundred women employed ascomputers at theMoore School of Electrical Engineering at the University of Pennsylvania. The job of computers was to produce the numeric result of mathematical formulas needed for a scientific study, or an engineering project. They usually did so with a mechanical calculator. The women studied the machine's logic, physical structure, operation, and circuitry in order to not only understand the mathematics of computing, but also the machine itself.[24] This was one of the few technical job categories available to women at that time.[52]Betty Holberton (née Snyder) continued on to help write the first generative programming system (SORT/MERGE) and help design the first commercial electronic computers, theUNIVAC and theBINAC, alongside Jean Jennings.[53] McNulty developed the use ofsubroutines in order to help increase ENIAC's computational capability.[54]
Herman Goldstine selected the programmers, whom he called operators, from the computers who had been calculating ballistics tables with mechanical desk calculators and a differential analyzer prior to and during the development of ENIAC.[24] Under Herman andAdele Goldstine's direction, the computers studied ENIAC's blueprints and physical structure to determine how to manipulate its switches and cables, asprogramming languages did not yet exist. Though contemporaries considered programming a clerical task and did not publicly recognize the programmers' effect on the successful operation and announcement of ENIAC,[24] McNulty, Jennings, Snyder, Wescoff, Bilas, and Lichterman have since been recognized for their contributions to computing.[55][56][57] Three of the current (2020) Army supercomputers,Jean,Kay, andBetty, are named afterJean Bartik (Betty Jennings),Kay McNulty, andBetty Snyder respectively.[58]
The "programmer" and "operator" job titles were not originally considered professions suitable for women. The labor shortage created by World War II helped enable the entry of women into the field.[24] However, the field was not viewed as prestigious, and bringing in women was viewed as a way to free men up for more skilled labor. Essentially, women were seen as meeting a need in a temporary crisis.[24] For example, the National Advisory Committee for Aeronautics said in 1942, "It is felt that enough greater return is obtained by freeing the engineers from calculating detail to overcome any increased expenses in the computers' salaries. The engineers admit themselves that the girl computers do the work more rapidly and accurately than they would. This is due in large measure to the feeling among the engineers that their college and industrial experience is being wasted and thwarted by mere repetitive calculation."[24]
Following the initial six programmers, an expanded team of a hundred scientists was recruited to continue work on the ENIAC. Among these were several women, includingGloria Ruth Gordon.[59] Adele Goldstine wrote the original technical description of the ENIAC.[60]
Related to ENIAC's role in the hydrogen bomb was its role in theMonte Carlo method becoming popular. Scientists involved in the original nuclear bomb development used massive groups of people doing huge numbers of calculations ("computers" in the terminology of the time) to investigate the distance that neutrons would likely travel through various materials.John von Neumann andStanislaw Ulam realized the speed of ENIAC would allow these calculations to be done much more quickly.[66] The success of this project showed the value of Monte Carlo methods in science.[67]
A press conference was held on February 1, 1946,[24] and the completed machine was announced to the public the evening of February 14, 1946,[68] featuring demonstrations of its capabilities. Elizabeth Snyder and Betty Jean Jennings were responsible for developing the demonstration trajectory program, although Herman and Adele Goldstine took credit for it.[24] The machine was formally dedicated the next day[69] at the University of Pennsylvania. None of the women involved in programming the machine or creating the demonstration were invited to the formal dedication nor to the celebratory dinner held afterwards.[70]
The original contract amount was $61,700; the final cost was almost $500,000 (approximately equivalent to $9,000,000 in 2024). It was formally accepted by the U.S. Army Ordnance Corps in July 1946. ENIAC was shut down on November 9, 1946, for a refurbishment and a memory upgrade, and was transferred toAberdeen Proving Ground,Maryland in 1947. There, on July 29, 1947, it was turned on and was in continuous operation until 11:45 p.m. on October 2, 1955, when it was retired in favor of the more efficientEDVAC andORDVAC computers.[2]
A few months after ENIAC's unveiling in the summer of 1946, as part of "an extraordinary effort to jump-start research in the field",[71]the Pentagon invited "the top people in electronics and mathematics from the United States and Great Britain"[71] to a series of forty-eight lectures given in Philadelphia, Pennsylvania; all together calledThe Theory and Techniques for Design of Digital Computers—more often named theMoore School Lectures.[71] Half of these lectures were given by the inventors of ENIAC.[72]
ENIAC was a one-of-a-kind design and was never repeated. The freeze on design in 1943 meant that it lacked some innovations that soon became well-developed, notably the ability to store a program. Eckert and Mauchly started work on a new design, to be later called theEDVAC, which would be both simpler and more powerful. In particular, in 1944 Eckert wrote his description of a memory unit (the mercurydelay line) which would hold both the data and the program. John von Neumann, who was consulting for the Moore School on the EDVAC, sat in on the Moore School meetings at which the stored program concept was elaborated. Von Neumann wrote up an incomplete set of notes (First Draft of a Report on the EDVAC) which were intended to be used as an internal memorandum—describing, elaborating, and couching in formal logical language the ideas developed in the meetings. ENIAC administrator and security officerHerman Goldstine distributed copies of thisFirst Draft to a number of government and educational institutions, spurring widespread interest in the construction of a new generation of electronic computing machines, includingElectronic Delay Storage Automatic Calculator (EDSAC) at Cambridge University, England andSEAC at the U.S. Bureau of Standards.[73]
A number of improvements were made to ENIAC after 1947, including a primitive read-only stored programming mechanism using the function tables as programROM,[73][74][75][76][77][78] after which programming was done by setting the switches.[79] The idea has been worked out in several variants by Richard Clippinger and his group, on the one hand, and the Goldstines, on the other,[80] and it was included in the ENIACpatent.[81] Clippinger consulted with von Neumann on what instruction set to implement.[73][82][83] Clippinger had thought of a three-address architecture while von Neumann proposed a one-address architecture because it was simpler to implement. Three digits of one accumulator (#6) were used as the program counter, another accumulator (#15) was used as the main accumulator, a third accumulator (#8) was used as the address pointer for reading data from the function tables, and most of the other accumulators (1–5, 7, 9–14, 17–19) were used for data memory.
In March 1948 the converter unit was installed,[84] which made possible programming through the reader from standard IBM cards.[85][86] The "first production run" of the new coding techniques on theMonte Carlo problem followed in April.[84][87] After ENIAC's move to Aberdeen, a register panel for memory was also constructed, but it did not work. A small master control unit to turn the machine on and off was also added.[88]
The programming of the stored program for ENIAC was done by Betty Jennings, Clippinger, Adele Goldstine and others.[89][90][74][73] It was first demonstrated as astored-program computer in April 1948,[91] running a program byAdele Goldstine for John von Neumann. This modification reduced the speed of ENIAC by a factor of 6 and eliminated the ability of parallel computation, but as it also reduced the reprogramming time[83][73] to hours instead of days, it was considered well worth the loss of performance. Also analysis had shown that due to differences between the electronic speed of computation and the electromechanical speed of input/output, almost any real-world problem was completelyI/O bound, even without making use of the original machine's parallelism. Most computations would still be I/O bound, even after the speed reduction imposed by this modification.
Early in 1952, a high-speed shifter was added, which improved the speed for shifting by a factor of five. In July 1953, a 100-word expansioncore memory was added to the system, usingbinary-coded decimal,excess-3 number representation. To support this expansion memory, ENIAC was equipped with a new Function Table selector, a memory address selector, pulse-shaping circuits, and three new orders were added to the programming mechanism.[73]
Mechanical computing machines have been around sinceArchimedes' time (see:Antikythera mechanism), but the 1930s and 1940s are considered the beginning of the modern computer era.
ENIAC was, like the IBMHarvard Mark I and the GermanZ3, able to run an arbitrary sequence of mathematical operations, but did not read them from a tape. Like the BritishColossus, it was programmed by plugboard and switches. ENIAC combined full,Turing-complete programmability with electronic speed. TheAtanasoff–Berry Computer (ABC), ENIAC, and Colossus all usedthermionic valves (vacuum tubes). ENIAC's registers performed decimal arithmetic, rather than binary arithmetic like the Z3, the ABC and Colossus.
Like the Colossus, ENIAC required rewiring to reprogram until April 1948.[92] In June 1948, theManchester Baby ran its first program and earned the distinction of first electronicstored-program computer.[93][94][95] Though the idea of a stored-program computer with combined memory for program and data was conceived during the development of ENIAC, it was not initially implemented in ENIAC because World War II priorities required the machine to be completed quickly, and ENIAC's 20 storage locations would be too small to hold data and programs.
The Z3 and Colossus were developed independently of each other, and of the ABC and ENIAC during World War II. Work on the ABC atIowa State University was stopped in 1942 afterJohn Atanasoff was called toWashington, D.C., to do physics research for the U.S. Navy, and it was subsequently dismantled.[96] The Z3 was destroyed by the Allied bombing raids of Berlin in 1943. As the ten Colossus machines were part of the UK's war effort their existence remained secret until the late 1970s, although knowledge of their capabilities remained among their UK staff and invited Americans. ENIAC, by contrast, was put through its paces for the press in 1946, "and captured the world's imagination". Older histories of computing may therefore not be comprehensive in their coverage and analysis of this period. All but two of the Colossus machines were dismantled in 1945; the remaining two were used to decrypt Soviet messages byGCHQ until the 1960s.[97][98] The public demonstration for ENIAC was developed by Snyder and Jennings who created a demo that would calculate the trajectory of a missile in 15 seconds, a task that would have taken several weeks for ahuman computer.[54]
For a variety of reasons – including Mauchly's June 1941 examination of theAtanasoff–Berry computer (ABC), prototyped in 1939 byJohn Atanasoff andClifford Berry – U.S. patent 3,120,606 for ENIAC, applied for in 1947 and granted in 1964, was voided by the 1973[99] decision of the landmark federal court caseHoneywell, Inc. v. Sperry Rand Corp.. The decision included: that the ENIAC inventors had derived the subject matter of the electronic digital computer from Atanasoff; gave legal recognition to Atanasoff as the inventor of the first electronic digital computer; and put the invention of the electronic digital computer in thepublic domain.
The bottoms of three accumulators at Fort Sill, Oklahoma, USA function table from ENIAC on display at Aberdeen Proving Ground museum
The main parts were 40 panels and three portable function tables (named A, B, and C). The layout of the panels was (clockwise, starting with the left wall):
Left wall
Initiating Unit
Cycling Unit
Master Programmer – panel 1 and 2
Function Table 1 – panel 1 and 2
Accumulator 1
Accumulator 2
Divider and Square Rooter
Accumulator 3
Accumulator 4
Accumulator 5
Accumulator 6
Accumulator 7
Accumulator 8
Accumulator 9
Back wall
Accumulator 10
High-speed Multiplier – panel 1, 2, and 3
Accumulator 11
Accumulator 12
Accumulator 13
Accumulator 14
Right wall
Accumulator 15
Accumulator 16
Accumulator 17
Accumulator 18
Function Table 2 – panel 1 and 2
Function Table 3 – panel 1 and 2
Accumulator 19
Accumulator 20
Constant Transmitter – panel 1, 2, and 3
Printer – panel 1, 2, and 3
An IBM card reader was attached to Constant Transmitter panel 3 and an IBM card punch was attached to Printer Panel 2. The Portable Function Tables could be connected to Function Table 1, 2, and 3.[100]
TheSmithsonian has five panels (Accumulators 2, 19, and 20; Constant Transmitter panels 1 and 3; Divider and Square Rooter; Function Table 2 panel 1; Function Table 3 panel 2; High-speed Multiplier panels 1 and 2; Printer panel 1; Initiating Unit)[100] in theNational Museum of American History in Washington, D.C.[24] (but apparently not currently on display).
TheScience Museum in London has a receiver unit on display.
TheComputer History Museum in Mountain View, California has three panels (Accumulator #12, Function Table 2 panel 2, and Printer Panel 3) and portable function table C on display (on loan from the Smithsonian Institution).[100]
The U.S. Army Field Artillery Museum inFort Sill, as of October 2014, obtained seven panels of ENIAC that were previously housed by The Perot Group in Plano, Texas.[102] There are accumulators #7, #8, #11, and #17;[103] panel #1 and #2 that connected to function table #1,[100] and the back of a panel showing its tubes. A module of tubes is also on display.
The Heinz Nixdorf Museum in Paderborn, Germany, has three panels (Printer panel 2 and High-speed Function Table)[100] (on loan from the Smithsonian Institution). In 2014 the museum decided to rebuild one of the accumulator panels – reconstructed part has the look and feel of a simplified counterpart from the original machine.[104][105]
ENIAC on a Chip, University of Pennsylvania (1995) - Computer History Museum
In 1996, in honor of the ENIAC's 50th anniversary, TheUniversity of Pennsylvania sponsored a project named "ENIAC-on-a-Chip", where a very smallsilicon computer chip measuring 7.44 mm by 5.29 mm was built with the same functionality as ENIAC. Although this 20 MHz chip was many times faster than ENIAC, it had but a fraction of the speed of its contemporary microprocessors in the late 1990s.[107][108][109]
In 1997, the six women who did most of the programming of ENIAC were inducted into theWomen in Technology International Hall of Fame.[55][110] The role of the ENIAC programmers is treated in a 2010 documentary film titledTop Secret Rosies: The Female "Computers" of WWII by LeAnn Erickson.[56] A 2014 documentary short,The Computers by Kate McMahon, tells of the story of the six programmers; this was the result of 20 years' research by Kathryn Kleiman and her team as part of the ENIAC Programmers Project.[57][111] In 2022Grand Central Publishing releasedProving Ground by Kathy Kleiman, a hardcover biography about the six ENIAC programmers and their efforts to translate block diagrams andelectronic schematics of the ENIAC, then under construction, into programs that would be loaded into and run on ENIAC once it was available for use.[112]
In 2011, in honor of the 65th anniversary of the ENIAC's unveiling, the city of Philadelphia declared February 15 as ENIAC Day.[113][114][115]
The ENIAC celebrated its 70th anniversary on February 15, 2016.[116]
^Eckert Jr., John Presper and Mauchly, John W.; Electronic Numerical Integrator and Computer, United States Patent Office,US Patent 3,120,606, filed 1947-06-26, issued 1964-02-04; invalidated 1973-10-19 after court ruling inHoneywell v. Sperry Rand.
^abWeik, Martin H."The ENIAC Story".Ordnance (January–February 1961). Washington, DC: American Ordnance Association. Archived fromthe original on August 14, 2011. RetrievedMarch 29, 2015.
^"ENIAC on Trial – 1. Public Use".www.ushistory.org. Search for1945. Archived fromthe original on February 9, 2019. RetrievedMay 16, 2018.The ENIAC machine [...] was reduced to practice no later than the date of commencement of the use of the machine for the Los Alamos calculations, December 10, 1945.
^Rhodes 1995, p. 251, chapter 13: The first problem assigned to the first working electronic digital computer in the world was the hydrogen bomb. […] The ENIAC ran a first rough version of the thermonuclear calculations for six weeks in December 1945 and January 1946.
^McCartney 1999, p. 103: "ENIAC correctly showed that Teller's scheme would not work, but the results led Teller and Ulam to come up with another design together."
^*"ENIAC on Trial – 1. Public Use".www.ushistory.org. Search for1945. RetrievedMay 16, 2018.The ENIAC machine […] was reduced to practice no later than the date of commencement of the use of the machine for the Los Alamos calculations, December 10, 1945.
^The original photo can be seen in the article:Rose, Allen (April 1946)."Lightning Strikes Mathematics".Popular Science:83–86. RetrievedMarch 29, 2015.
^Clippinger 1948, Section I: General Description of the ENIAC – The Function Tables.
^abMcCabe, Seabright (June 3, 2019)."The Programming Pioneers of ENIAC".All Together. No. Spring 2019. Society of Women Engineers.Archived from the original on December 25, 2023. RetrievedJuly 8, 2020.
^Booth, Kathleen. "Machine Language for Automatic Relay Computer".Birkbeck College Computation Laboratory. University of London.
^Campbell-Kelly, Martin "The Development of Computer Programming in Britain (1945 to 1955)", The Birkbeck College Machines, in (1982) Annals of the History of Computing 4(2) April 1982 IEEE
^Honeywell, Inc. v. Sperry Rand Corp., 180 U.S.P.Q. (BNA) 673, p. 20, finding 1.1.3 (U.S. District Court for the District of Minnesota, Fourth Division 1973) ("The ENIAC machine which embodied 'the invention' claimed by the ENIAC patent was in public use and non-experimental use for the following purposes, and at times prior to the critical date: ... Formal dedication use February 15, 1946 ...").
^McCartney 1999, p. 140: "Eckert gave eleven lectures, Mauchly gave six, Goldstine gave six. von Neumann, who was to give one lecture, didn't show up; the other 24 were spread among various invited academics and military officials."
^abcdef"Eniac".Epic Technology for Great Justice. RetrievedJanuary 28, 2017.
^Fritz, W. Barkley (1949)."Description and Use of the ENIAC Converter Code".Technical Note (141). Section 1. – Introduction, p. 1.At present it is controlled by a code which incorporates a unit called the Converter as a basic part of its operation, hence the name ENIAC Converter Code. These code digits are brought into the machine either through the Reader from standard IBM cards*or from the Function Tables (...). (...) *The card control method of operation is used primarily for testing and the running of short highly iterative problems and is not discussed in this report.
^Van Der Spiegel, Jan (1996)."ENIAC-on-a-Chip".PENN PRINTOUT. Vol. 12, no. 4. The University of Pennsylvania. Archived fromthe original on October 11, 2012. RetrievedOctober 17, 2016.
^Van Der Spiegel, Jan (May 9, 1995)."ENIAC-on-a-Chip". University of Pennsylvania. RetrievedSeptember 4, 2009.
^Kleiman, Kathy (July 2022).Proving Ground: The Untold Story of the Six Women Who Programmed the World's First Modern Computer. Grand Central Publishing.ISBN978-1-5387-1828-5.
De Mol, Liesbeth; Bullynck, Maarten (2008)."A Week-End Off: The First Extensive Number-Theoretical Computation on ENIAC". In Beckmann, Arnold; Dimitracopoulos, Costas; Löwe, Benedikt (eds.).Logic and Theory of Algorithms: 4th Conference on Computability in Europe, CiE 2008 Athens, Greece, June 15-20, 2008, Proceedings. Springer Science & Business Media. pp. 158–167.ISBN9783540694052.
Eckert, J. Presper,The ENIAC (in Nicholas Metropolis,J. Howlett, Gian-Carlo Rota, (editors),A History of Computing in the Twentieth Century, Academic Press, New York, 1980, pp. 525–540)
Eckert, J. Presper andJohn Mauchly, 1946,Outline of plans for development of electronic computers, 6 pages. (The founding document in the electronic computer industry.)
Fritz, W. Barkley,The Women of ENIAC (inIEEE Annals of the History of Computing, Vol. 18, 1996, pp. 13–28)
Goldstine, Adele K. (July 10, 1947).Central Control for ENIAC. p. 1.Unlike the later 60- and 100-order codes this one [51 order code] required no additions to ENIAC's original hardware. It would have worked more slowly and offered a more restricted range of instructions but the basic structure of accumulators and instructions changed only slightly.
Mauchly, John,The ENIAC (in Metropolis, Nicholas,Howlett, Jack; Rota, Gian-Carlo. 1980,A History of Computing in the Twentieth Century,Academic Press, New York,ISBN0-12-491650-3, pp. 541–550, "Original versions of these papers were presented at the International Research Conference on the History of Computing, held at theLos Alamos Scientific Laboratory, 10–15 June 1976.")
Berkeley, Edmund.GIANT BRAINS or machines that think. John Wiley & Sons, inc., 1949. Chapter 7Speed – 5000 Additions a Second: Moore School's ENIAC (Electronic Numerical Integrator And Computer)
Interview with Eckert Transcript of a video interview with Eckert by David Allison for the National Museum of American History, Smithsonian Institution on February 2, 1988. An in-depth, technical discussion on ENIAC, including the thought process behind the design.
Oral history interview with J. Presper Eckert,Charles Babbage Institute, University of Minnesota. Eckert, a co-inventor of ENIAC, discusses its development at the University of Pennsylvania's Moore School of Electrical Engineering; describes difficulties in securing patent rights for ENIAC and the problems posed by the circulation of John von Neumann's 1945First Draft of the Report on EDVAC, which placed the ENIAC inventions in the public domain. Interview by Nancy Stern, 28 October 1977.
Oral history interview with Carl Chambers,Charles Babbage Institute, University of Minnesota. Chambers discusses the initiation and progress of the ENIAC project at the University of Pennsylvania Moore School of Electrical Engineering (1941–46). Oral history interview by Nancy B. Stern, 30 November 1977.
Oral history interview with Irven A. Travis,Charles Babbage Institute, University of Minnesota. Travis describes the ENIAC project at the University of Pennsylvania (1941–46), the technical and leadership abilities of chief engineer Eckert, the working relations between John Mauchly and Eckert, the disputes over patent rights, and their resignation from the university. Oral history interview by Nancy B. Stern, 21 October 1977.
Oral history interview with S. Reid Warren,Charles Babbage Institute, University of Minnesota. Warren served as supervisor of the EDVAC project; central to his discussion are J. Presper Eckert and John Mauchly and their disagreements with administrators over patent rights; discusses John von Neumann's 1945 draft report on the EDVAC, and its lack of proper acknowledgment of all the EDVAC contributors.
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