Although ENIAC was designed and primarily used to calculate artillery firing tables for the United States Army 's Ballistic Research Laboratory which later became a part of the Army Research Laboratory ,   its first program was a study of the feasibility of the thermonuclear weapon.
The combination of speed and programmability allowed for thousands more calculations for problems, as ENIAC calculated a trajectory in 30 seconds that took a human 20 hours allowing one ENIAC hour to displace 2, human hours. It was formally accepted by the U. Army Ordnance Corps in July Herman H.
Goldstine persuaded the Army to fund the project, which put him in charge to oversee it for them. Presper Eckert of the University of Pennsylvania, U. ENIAC was a 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-digit decimal number in memory. Numbers were passed between these units across several general-purpose buses or trays , 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.
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Key to its versatility was the ability to branch ; it could trigger different operations, depending on the sign of a computed result.
By the end of its operation in , ENIAC contained 20, vacuum tubes ; 7, crystal diodes ; 1, relays ; 70, resistors ; 10, capacitors ; and approximately 5,, hand- soldered joints. While ENIAC had no system to store memory in its inception, these punch cards could be used for external memory storage.
ENIAC used ten-position ring counters to store digits; each digit required 36 vacuum tubes, 10 of which were the dual triodes making up the flip-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 mechanical adding machine.
ENIAC had 20 ten-digit signed accumulators , which used ten's complement representation and could perform 5, simple addition or subtraction operations between any of them and a source e. It was possible to connect several accumulators to run simultaneously, so the peak speed of operation was potentially much higher, due to parallel operation. It was possible to wire the carry of one accumulator into another accumulator to perform double precision arithmetic, but the accumulator carry circuit timing prevented the wiring of three or more for even higher precision.
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.
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The references by Rojas and Hashagen or Wilkes  give more details about the times for operations, which differ somewhat from those stated above. If one of the numbers had fewer than 10 digits, the operation was faster. So a division or square root took up to cycles, or 28, microseconds—a rate of 35 per second. Wilkes  states that a division with a 10 digit quotient required 6 milliseconds. If the result had fewer than ten digits, it was obtained faster.
Special high-reliability tubes were not available until 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.
According to an interview in with Eckert, "We had a tube fail about every two days and we could locate the problem within 15 minutes. ENIAC could be programmed to perform complex sequences of operations, including loops, branches, and subroutines. However, instead of the stored-program computers that exist today, ENIAC was just a large collection of arithmetic machines, which originally had programs set up into the machine  by a combination of plugboard wiring and three portable function tables containing ten-way switches each.
Due to the complexity of mapping programs onto the machine, programs were only changed after huge numbers of tests of the current program.
This was followed by a period of verification and debugging, aided by the ability to execute the program step by step. They were not, as computer scientist and historian Kathryn Kleiman was once told, "refrigerator ladies", i.
These early programmers were drawn from a group of about two hundred women employed as computers at the Moore 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. This was one of the few technical job categories available to women at that time. 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. Though contemporaries considered programming a clerical task and did not publicly recognize the programmers' impact on the successful operation and announcement of ENIAC,  McNulty, Jennings, Snyder, Wescoff, Bilas, and Lichterman have since been recognized for their contributions to computing.
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. For example, the National Advisory Committee for Aeronautics said in , "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".
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, including Gloria Ruth Gordon. 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.
A press conference was held on February 1, ,  and the completed machine was announced to the public the evening of February 14, ,  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.
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. A few months after ENIAC's unveiling in the summer of , as part of "an extraordinary effort to jump-start research in the field",  the Pentagon invited "the top people in electronics and mathematics from the United States and Great Britain"  to a series of forty-eight lectures given in Philadelphia, Pennsylvania; all together called The Theory and Techniques for Design of Digital Computers —more often named the Moore School Lectures.
ENIAC was a one-of-a-kind design and was never repeated.
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The freeze on design in meant that the computer design would lack 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 the EDVAC , which would be both simpler and more powerful. In particular, in Eckert wrote his description of a memory unit the mercury delay line which would hold both the data and the program.
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. Bureau of Standards.
A number of improvements were made to ENIAC after , including a primitive read-only stored programming mechanism using the function tables as program ROM ,    after which programming was done by setting the switches.
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 the converter unit was installed,  which made possible programming through the reader from standard IBM cards. A small master control unit to turn the machine on and off was also added.
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   to hours instead of days, it was considered well worth the loss of performance. Early in , a high-speed shifter was added, which improved the speed for shifting by a factor of five.
In July , a word expansion core memory was added to the system, using binary-coded decimal , excess-3 number representation.
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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. Mechanical computing machines have been around since Archimedes ' time see: Antikythera mechanism , but the s and s are considered the beginning of the modern computer era. Like the British Colossus , it was programmed by plugboard and switches.
Navy, and it was subsequently dismantled. As the ten Colossus machines were part of the UK's war effort their existence remained secret until the late s, 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 , "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 machine were dismantled in ; the remaining two were used to decrypt Soviet messages by GCHQ until the s.
Patent 3,, for ENIAC, applied for in and granted in , was voided by the decision of the landmark federal court case Honeywell v. Sperry Rand , putting the invention of the electronic digital computer in the public domain and providing legal recognition to Atanasoff as the inventor of the first electronic digital computer. 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 :. By July von Neumann was writing: "I am much obliged to Adele for her letters. Nick and I are working with her new code, and it seems excellent.
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Esta línea del tiempo trata sobre como ha evolucionado la computadora durante los años.
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See also: History of Monte Carlo method. Main article: History of computing hardware. Main article: Honeywell v. Sperry Rand. Archived from the original on Retrieved Engines of the mind: the evolution of the computer from mainframes to microprocessors. New York: Norton.
January US Army Research Laboratory. The first problem assigned to the first working electronic digital computer in the world was the hydrogen bomb. Public Use". Search for 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, About the court case more sources : Honeywell, Inc.
Sperry Rand Corp.