ENIAC

ENIAC

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ENIAC was the first general-purpose electronic computer
Computer
A computer is a programmable machine designed to sequentially and automatically carry out a sequence of arithmetic or logical operations. The particular sequence of operations can be changed readily, allowing the computer to solve more than one kind of problem...

. It was a Turing-complete digital computer capable of being reprogrammed to solve a full range of computing problems.

ENIAC was designed to calculate artillery
Artillery
Originally applied to any group of infantry primarily armed with projectile weapons, artillery has over time become limited in meaning to refer only to those engines of war that operate by projection of munitions far beyond the range of effect of personal weapons...

 firing tables
External ballistics
External ballistics is the part of the science of ballistics that deals with the behaviour of a non-powered projectile in flight. External ballistics is frequently associated with firearms, and deals with the behaviour of the bullet after it exits the barrel and before it hits the target.-Forces...

 for the United States Army
United States Army
The United States Army is the main branch of the United States Armed Forces responsible for land-based military operations. It is the largest and oldest established branch of the U.S. military, and is one of seven U.S. uniformed services...

's Ballistic Research Laboratory
Ballistic Research Laboratory
The Ballistic Research Laboratory at Aberdeen Proving Ground, Maryland was the center for the United States Army's research efforts in ballistics and vulnerability/lethality analysis....

.
When ENIAC was announced in 1946 it was heralded in the press as a "Giant Brain". It boasted speeds one thousand times faster than electro-mechanical machines, a leap in computing power that no single machine has since matched. This mathematical power, coupled with general-purpose programmability, excited scientists and industrialists. The inventors promoted the spread of these new ideas by teaching a series of lectures
Moore School Lectures
Theory and Techniques for Design of Electronic Digital Computers was a course in the construction of electronic digital computers held at the University of Pennsylvania's Moore School of Electrical Engineering between July 8, 1946 and August 30, 1946, and was the first time any computer topics had...

 on computer architecture.

The ENIAC's design and construction was financed by the United States Army during World War II
World War II
World War II, or the Second World War , was a global conflict lasting from 1939 to 1945, involving most of the world's nations—including all of the great powers—eventually forming two opposing military alliances: the Allies and the Axis...

. The construction contract was signed on June 5, 1943, and work on the computer began in secret by the University of Pennsylvania
University of Pennsylvania
The University of Pennsylvania is a private, Ivy League university located in Philadelphia, Pennsylvania, United States. Penn is the fourth-oldest institution of higher education in the United States,Penn is the fourth-oldest using the founding dates claimed by each institution...

's Moore School of Electrical Engineering
Moore School of Electrical Engineering
The Moore School of Electrical Engineering at the University of Pennsylvania came into existence as a result of an endowment from Alfred Fitler Moore on June 4, 1923. It was granted to Penn's School of Electrical Engineering, located in the Towne Building...

 starting the following month under the code name "Project PX". The completed machine was announced to the public the evening of February 14, 1946 and formally dedicated the next day at the University of Pennsylvania, having cost almost $500,000 (nearly $6 million in 2010, adjusted for inflation). 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 to Aberdeen Proving Ground
Aberdeen Proving Ground
Aberdeen Proving Ground is a United States Army facility located near Aberdeen, Maryland, . Part of the facility is a census-designated place , which had a population of 3,116 at the 2000 census.- History :...

, Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

 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.

ENIAC was conceived and designed by John Mauchly
John Mauchly
John William Mauchly was an American physicist who, along with J. Presper Eckert, designed ENIAC, the first general purpose electronic digital computer, as well as EDVAC, BINAC and UNIVAC I, the first commercial computer made in the United States.Together they started the first computer company,...

 and J. Presper Eckert
J. Presper Eckert
John Adam Presper "Pres" Eckert Jr. was an American electrical engineer and computer pioneer. With John Mauchly he invented the first general-purpose electronic digital computer , presented the first course in computing topics , founded the first commercial computer company , and...

 of the University of Pennsylvania. The team of design engineers assisting the development included Robert F. Shaw (function tables), Chuan Chu (divider/square-rooter), Thomas Kite Sharpless (master programmer), Arthur Burks
Arthur Burks
Arthur Walter Burks was an American mathematician who in the 1940s as a senior engineer on the project contributed to the design of the ENIAC, the first general-purpose electronic digital computer. Decades later, Burks and his wife Alice Burks outlined their case for the subject matter of the...

 (multiplier), Harry Huskey
Harry Huskey
Harry Douglas Huskey is an American computer designer pioneer.Huskey was born in the Smoky Mountains region of North Carolina and grew up in Idaho. He gained his Master's and then his PhD in 1943 from the Ohio State University on Contributions to the Problem of Geocze...

 (reader/printer) and Jack Davis (accumulators). ENIAC was named an IEEE Milestone in 1987.

Description



The ENIAC was a modular computer, composed of individual panels to perform different functions. Twenty of these modules were accumulators, which could not only add and subtract but hold a ten-digit decimal
Decimal
The decimal numeral system has ten as its base. It is the numerical base most widely used by modern civilizations....

 number in memory. Numbers were passed between these units across a number of 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. Key to its versatility was the ability to branch; it could trigger different operations that depended on the sign of a computed result.

Besides its speed, the most remarkable thing about ENIAC was its size and complexity. ENIAC contained 17,468 vacuum tube
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

s, 7,200 crystal diode
Diode
In electronics, a diode is a type of two-terminal electronic component with a nonlinear current–voltage characteristic. A semiconductor diode, the most common type today, is a crystalline piece of semiconductor material connected to two electrical terminals...

s, 1,500 relay
Relay
A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal , or where several circuits must be controlled...

s, 70,000 resistor
Resistor
A linear resistor is a linear, passive two-terminal electrical component that implements electrical resistance as a circuit element.The current through a resistor is in direct proportion to the voltage across the resistor's terminals. Thus, the ratio of the voltage applied across a resistor's...

s, 10,000 capacitor
Capacitor
A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...

s and around 5 million hand-solder
Solder
Solder is a fusible metal alloy used to join together metal workpieces and having a melting point below that of the workpiece.Soft solder is what is most often thought of when solder or soldering are mentioned and it typically has a melting range of . It is commonly used in electronics and...

ed joints. It weighed more than 30 short ton
Short ton
The short ton is a unit of mass equal to . In the United States it is often called simply ton without distinguishing it from the metric ton or the long ton ; rather, the other two are specifically noted. There are, however, some U.S...

s (27 t), was roughly 8 by 3 by 100 feet (2.4 m × 0.9 m × 30 m), took up 1800 square feet (167 m2), and consumed 150 kW of power. Input was possible from an IBM card reader, and an IBM card punch was used for output. These cards could be used to produce printed output offline using an IBM
IBM
International Business Machines Corporation or IBM is an American multinational technology and consulting corporation headquartered in Armonk, New York, United States. IBM manufactures and sells computer hardware and software, and it offers infrastructure, hosting and consulting services in areas...

 accounting machine, such as the IBM 405.

ENIAC used ten-position ring counter
Ring counter
A ring counter is a type of counter composed of a circular shift register. The output of the last shift register is fed to the input of the first register.There are two types of ring counters:...

s to store digits; each digit used 36 vacuum tubes, 10 of which were the dual triodes making up the flip-flops
Flip-flop (electronics)
In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic...

 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 emulate in electronics the operation of the digit wheels of a mechanical adding machine
Adding machine
An adding machine was a class of mechanical calculator, usually specialized for bookkeeping calculations.In the United States, the earliest adding machines were usually built to read in dollars and cents. Adding machines were ubiquitous office equipment until they were phased out in favor of...

. ENIAC had twenty ten-digit signed accumulators
Accumulator (computing)
In a computer's central processing unit , an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation to main memory, perhaps only to be read right back again for...

 which used ten'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) every 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.

It was possible to wire the carry of one accumulator into another accumulator to perform double precision
Double precision
In computing, double precision is a computer number format that occupies two adjacent storage locations in computer memory. A double-precision number, sometimes simply called a double, may be defined to be an integer, fixed point, or floating point .Modern computers with 32-bit storage locations...

 arithmetic, but the accumulator carry circuit timing prevented the wiring of three or more for higher precision. The ENIAC used four of the accumulators, controlled by a special Multiplier unit, to perform up to 385 multiplication operations per second. The ENIAC also used five of the accumulators, controlled by a special Divider/Square-Rooter unit, to perform up to forty division operations per second or three square root
Square root
In mathematics, a square root of a number x is a number r such that r2 = x, or, in other words, a number r whose square is x...

 operations per second.

The other nine units in ENIAC were the Initiating Unit (which started and stopped the machine), the Cycling Unit (used for synchronizing the other units), the Master Programmer (which controlled "loop" sequencing), the Reader (which controlled an IBM punched card reader), the Printer (which controlled an IBM punched card punch), the Constant Transmitter, and three Function Tables.
The references by Rojas and Hashagen (or Wilkes) give more details about the times for operations, which differ somewhat from those stated above. The basic machine cycle was 200 microseconds (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 a d-digit number (for d up to 10) took d+4 cycles, so a 10- by 10-digit multiplication took 14 cycles, or 2800 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, where d 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 states that a division with a 10 digit quotient required 6 milliseconds.) If the result had fewer than ten digits, it was obtained faster.

Reliability


ENIAC used common octal-base radio tubes of the day; the decimal accumulators
Accumulator (computing)
In a computer's central processing unit , an accumulator is a register in which intermediate arithmetic and logic results are stored. Without a register like an accumulator, it would be necessary to write the result of each calculation to main memory, perhaps only to be read right back again for...

 were made of 6SN7
6SN7
6SN7 is a dual triode vacuum tube, on an 8 pin octal base. Although the 6S—series tubes are often metal cased, the 6SN7 is generally found only in a glass GT size envelope. The 6SN7 is basically two 6J5 triodes in one glass envelope.-History:...

 flip-flops
Flip-flop (electronics)
In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic...

, while 6L7s, 6SJ7s, 6SA7s and 6AC7s were used in logic functions. Numerous 6L6
6L6
6L6 is the designator for a vacuum tube introduced by Radio Corporation of America in July 1936. At the time Philips had already developed and patented power pentode designs, which were fast replacing power triodes due to their greater efficiency...

s and 6V6
6V6
The 6V6 is a beam-power tetrode, introduced by Radio Corporation of America RCA United States in late 1937, and still in use in niche applications.Similar to its predecessor the 6L6, the 6V6 was far more widely used...

s served as line drivers to drive pulses through cables between rack assemblies.


Some electronics experts predicted that tube failures would occur so frequently that the machine would never be useful. This prediction turned out to be partially correct: several tubes burned out almost every day, leaving it 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. By the simple but costly expedient of never turning the machine off, the engineers reduced ENIAC's tube failures to the more acceptable rate of one tube every two days. According to a 1989 interview with Eckert the continuously failing tubes story was therefore mostly a myth: "We had a tube fail about every two days and we could locate the problem within 15 minutes."
In 1954, the longest continuous period of operation without a failure was 116 hours (close to five days).

Programming


Although the Ballistic Research Laboratory was the sponsor of ENIAC, one year into this three-year project John von Neumann
John von Neumann
John von Neumann was a Hungarian-American mathematician and polymath who made major contributions to a vast number of fields, including set theory, functional analysis, quantum mechanics, ergodic theory, geometry, fluid dynamics, economics and game theory, computer science, numerical analysis,...

, a mathematician working on the hydrogen bomb at Los Alamos
Los Alamos National Laboratory
Los Alamos National Laboratory is a United States Department of Energy national laboratory, managed and operated by Los Alamos National Security , located in Los Alamos, New Mexico...

, became aware of this computer. Los Alamos subsequently became so involved with ENIAC that the first test problem run was computations for the hydrogen bomb, not artillery tables. The input/output for this test was one million cards.

The ENIAC could be programmed to perform complex sequences of operations, which could include loops, branches, and subroutines. The task of taking a problem and mapping it onto the machine was complex, and usually took weeks. After the program was figured out on paper, the process of getting the program "into" the ENIAC by manipulating its switches and cables took additional days. This was followed by a period of verification and debugging, aided by the ability to "single step" the machine.

The six women who did most of the programming of ENIAC were inducted in 1997 into the Women in Technology International Hall of Fame. As they were called by each other in 1946, they were Kay McNulty
Kathleen Antonelli
Kathleen "Kay" McNulty Mauchly Antonelli was one of the six original programmers of the ENIAC, the first general-purpose electronic digital computer.-Early life and education:...

, Betty Jennings
Jean Bartik
Jean Bartik was one of the original programmers for the ENIAC computer.She was born Betty Jean Jennings in Gentry County, Missouri, in 1924 and attended Northwest Missouri State Teachers College, majoring in mathematics. In 1945, she was hired by the University of Pennsylvania to work for Army...

, Betty Snyder
Betty Holberton
Frances Elizabeth "Betty" Holberton was one of the six original programmers of ENIAC, the first general-purpose electronic digital computer.-Early life and education:...

, Marlyn Wescoff
Marlyn Meltzer
Marlyn Meltzer was one of the original programmers for the ENIAC computer.She was born Marlyn Wescoff and graduated from Temple University in 1942. She was hired by the Moore School of Engineering later that year to perform weather calculations, mainly because she knew how to operate an adding...

, Fran Bilas
Frances Spence
Frances Spence was one of the original programmers for the ENIAC computer.She was born Frances Bilas in Philadelphia in 1922. She attended Temple University but then was awarded a scholarship to Chestnut Hill College. She majored in mathematics with a minor in physics and graduated in 1942...

 and Ruth Lichterman
Ruth Teitelbaum
Ruth Teitelbaum was one of the original programmers for the ENIAC computer.Teitelbaum graduated from Hunter College with a B.Sc. in Mathematics...

. Jennifer S. Light
Jennifer S. Light
Jennifer S. Light is Associate Professor of Communication Studies, History, and Sociology and a Faculty Associate at the Institute for Policy Research at Northwestern University. Light's research investigates the work of technical experts in the political process, with special interest in these...

's essay, "When Computers Were Women", documents and describes the role of the women of ENIAC as well as outlines the historical omission or downplay of women's roles in computer science history. The role of the ENIAC programmers was also treated in a 2010 documentary film by LeAnn Erickson.

ENIAC was a one-of-a-kind design and was never repeated. The freeze on design in 1943 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
EDVAC
EDVAC was one of the earliest electronic computers. Unlike its predecessor the ENIAC, it was binary rather than decimal, and was a stored program computer....

, which would be both simpler and more powerful. In particular, in 1944 Eckert wrote his description of a memory unit (the mercury delay line
Delay line memory
Delay line memory was a form of computer memory used on some of the earliest digital computers. Like many modern forms of electronic computer memory, delay line memory was a refreshable memory, but as opposed to modern random-access memory, delay line memory was serial-access...

) 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, and wrote up an incomplete set of notes (First Draft of a Report on the EDVAC
First Draft of a Report on the EDVAC
The First Draft of a Report on the EDVAC was an incomplete 101-page document written by John von Neumann and distributed on June 30, 1945 by Herman Goldstine, security officer on the classified ENIAC project...

) 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 officer Herman Goldstine distributed copies of the First Draft to a number of government and educational institutions, spurring widespread interest in the construction of a new generation of electronic computing machines, including EDSAC
EDSAC
Electronic Delay Storage Automatic Calculator was an early British computer. The machine, having been inspired by John von Neumann's seminal First Draft of a Report on the EDVAC, was constructed by Maurice Wilkes and his team at the University of Cambridge Mathematical Laboratory in England...

 and SEAC
SEAC (computer)
SEAC was a first-generation electronic computer, built in 1950 by the U.S. National Bureau of Standards and was initially called the National Bureau of Standards Interim Computer, because it was a small-scale computer designed to be built quickly and put into operation while the NBS waited for...

.

A number of improvements were also made to ENIAC from 1948, including a primitive read-only stored programming mechanism using the Function Tables as program ROM
Read-only memory
Read-only memory is a class of storage medium used in computers and other electronic devices. Data stored in ROM cannot be modified, or can be modified only slowly or with difficulty, so it is mainly used to distribute firmware .In its strictest sense, ROM refers only...

, an idea included in the ENIAC patent and proposed independently by Dr. Richard Clippinger of the BRL. Clippinger consulted with von Neumann on what instruction set to implement. Clippinger had thought of a 3-address architecture while von Neumann proposed a 1-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. The programming of the stored program for ENIAC was done by Betty Jennings, Clippinger and Adele Goldstine. It was first demonstrated as a stored-program computer
Stored-program computer
A stored-program computer is one which stores program instructions in electronic memory. Often the definition is extended with the requirement that the treatment of programs and data in memory be interchangeable or uniform....

 on September 16, 1948, running a program by Adele Goldstine
Adele Goldstine
Adele Goldstine , born Adele Katz, wrote the complete technical description for the first electronic digital computer, ENIAC...

 for John von Neumann. This modification reduced the speed of ENIAC by a factor of six 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. 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 completely I/O bound even without making use of the original machine's parallelism and most would still be I/O bound even after the speed reduction from 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 expansion core memory was added to the system, using binary coded decimal, excess-3
Excess-3
Excess-3 binary-coded decimal ' or Stibitz code, also called biased representation or Excess-N, is a complementary BCD code and numeral system it is used on some older computers that uses a pre-specified number N as a biasing value. It is a way to represent values with a balanced number of positive...

 number representation. To support this expansion memory, the 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.

Comparison with other early computers


Mechanical and electrical computing machines have been around since the 19th century, but the 1930s and 1940s are considered the beginning of the modern computer era.
  • The German Z3 (shown working in May 1941) was designed by Konrad Zuse
    Konrad Zuse
    Konrad Zuse was a German civil engineer and computer pioneer. His greatest achievement was the world's first functional program-controlled Turing-complete computer, the Z3, which became operational in May 1941....

    . It was the first general-purpose digital computer, but it was electromechanical, rather than electronic, as it used relay
    Relay
    A relay is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal , or where several circuits must be controlled...

    s for all functions. It computed logically using binary math. It was programmable by punched tape, but lacked the conditional branch. While not designed for Turing-completeness, it accidentally was, as it was found out in 1998 (but to exploit this Turing-completeness, complex, clever hacks were necessary). It was destroyed in a bombing raid on Berlin in December 1943.
  • The American Atanasoff–Berry Computer (ABC) (shown working in summer 1941) was the first electronic computing device. It implemented binary computation with vacuum tubes but was not general purpose, being limited to solving systems of linear equations. It also did not exploit electronic computing speeds, being limited by a rotating capacitor
    Capacitor
    A capacitor is a passive two-terminal electrical component used to store energy in an electric field. The forms of practical capacitors vary widely, but all contain at least two electrical conductors separated by a dielectric ; for example, one common construction consists of metal foils separated...

     drum memory and an input-output system that was intended to write intermediate results to paper cards. It was manually controlled and was not programmable.
  • The ten British Colossus computer
    Colossus computer
    Not to be confused with the fictional computer of the same name in the movie Colossus: The Forbin Project.Colossus was the world's first electronic, digital, programmable computer. Colossus and its successors were used by British codebreakers to help read encrypted German messages during World War II...

    s (used for cryptanalysis
    Cryptanalysis
    Cryptanalysis is the study of methods for obtaining the meaning of encrypted information, without access to the secret information that is normally required to do so. Typically, this involves knowing how the system works and finding a secret key...

     starting in 1943) were designed by Tommy Flowers
    Tommy Flowers
    Thomas "Tommy" Harold Flowers, MBE was an English engineer. During World War II, Flowers designed Colossus, the world's first programmable electronic computer, to help solve encrypted German messages.-Early life:...

    . The Colossus computers were digital, electronic, and were programmed by plugboard and switches, but they were dedicated to code breaking and not general purpose.
  • Howard Aiken
    Howard Aiken
    Howard Hathaway Aiken was a pioneer in computing, being the original conceptual designer behind IBM's Harvard Mark I computer....

    's 1944 Harvard Mark I
    Harvard Mark I
    The IBM Automatic Sequence Controlled Calculator , called the Mark I by Harvard University, was an electro-mechanical computer....

     was programmed by punched tape and used relays. It performed general math functions, but lacked any branching.
  • The ENIAC was, like the Z3 and Mark I, able to run an arbitrary sequence of mathematical operations, but did not read them from a tape. Like the Colossus, it was programmed by plugboard and switches. The ENIAC combined full, Turing complete programmability with electronic speed.

The ABC, ENIAC and Colossus all used thermionic valves (vacuum tubes)
Vacuum tube
In electronics, a vacuum tube, electron tube , or thermionic valve , reduced to simply "tube" or "valve" in everyday parlance, is a device that relies on the flow of electric current through a vacuum...

. ENIAC's registers performed decimal arithmetic, rather than binary arithmetic like the Z3 or the Atanasoff-Berry Computer.

Until 1948, ENIAC required rewiring to reprogram, like the Colossus. The idea of the stored-program computer with combined memory for program and data was conceived during the development of the ENIAC, but it was not initially implemented in the ENIAC because World War II priorities required the machine to be completed quickly, and the ENIAC's 20 storage locations would be too small to hold data and programs.

Public knowledge


The Z3 and Colossus were developed independently of each other and of the ABC and the ENIAC during World War II. The Z3 was destroyed by Allied bombing of Berlin in 1943. The Colossus machines were part of the UK's war effort. Their existence only became generally known in the 1970s, though knowledge of their capabilities remained among their UK staff and invited Americans. All but two of the machines that remained in use in GCHQ until the 1960s, were destroyed in 1945. The ABC was dismantled by Iowa State University
Iowa State University
Iowa State University of Science and Technology, more commonly known as Iowa State University , is a public land-grant and space-grant research university located in Ames, Iowa, United States. Iowa State has produced astronauts, scientists, and Nobel and Pulitzer Prize winners, along with a host of...

, after John Atanasoff was called to Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

 to do physics research for the U.S. Navy. 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.

Patent



For a variety of reasons (including Mauchly's June 1941 examination of the Atanasoff–Berry Computer, prototyped in 1939 by John Atanasoff and Clifford Berry
Clifford Berry
Clifford Edward Berry was an American inventor.Clifford Berry was born in Gladbrook, Iowa to Fred Gordon Berry and Grace Strohm...

), US patent 3,120,606 for the ENIAC, granted in 1964, was voided by the 1973 decision of the landmark federal court case Honeywell v. Sperry Rand, putting the invention of the electronic digital computer in the public domain
Public domain
Works are in the public domain if the intellectual property rights have expired, if the intellectual property rights are forfeited, or if they are not covered by intellectual property rights at all...

 and providing legal recognition to Atanasoff as the inventor of the first electronic digital computer.

Parts on display



The School of Engineering and Applied Science at the University of Pennsylvania has four of the original forty panels and one of the three function tables of the ENIAC. The Smithsonian
Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...

 has five panels in the National Museum of American History
National Museum of American History
The National Museum of American History: Kenneth E. Behring Center collects, preserves and displays the heritage of the United States in the areas of social, political, cultural, scientific and military history. Among the items on display are the original Star-Spangled Banner and Archie Bunker's...

 in Washington D.C. The Science Museum
Science museum
A science museum or a science centre is a museum devoted primarily to science. Older science museums tended to concentrate on static displays of objects related to natural history, paleontology, geology, industry and industrial machinery, etc. Modern trends in museology have broadened the range of...

 in London has a receiver unit on display. The Computer History Museum
Computer History Museum
The Computer History Museum is a museum established in 1996 in Mountain View, California, USA. The Museum is dedicated to preserving and presenting the stories and artifacts of the information age, and exploring the computing revolution and its impact on our lives.-History:The museum's origins...

 in Mountain View, California has a single panel on display. The University of Michigan
University of Michigan
The University of Michigan is a public research university located in Ann Arbor, Michigan in the United States. It is the state's oldest university and the flagship campus of the University of Michigan...

 in Ann Arbor has four panels, salvaged by Arthur Burks. The U.S. Army Ordnance Museum at Aberdeen Proving Ground
Aberdeen Proving Ground
Aberdeen Proving Ground is a United States Army facility located near Aberdeen, Maryland, . Part of the facility is a census-designated place , which had a population of 3,116 at the 2000 census.- History :...

, Maryland
Maryland
Maryland is a U.S. state located in the Mid Atlantic region of the United States, bordering Virginia, West Virginia, and the District of Columbia to its south and west; Pennsylvania to its north; and Delaware to its east...

, where ENIAC was used, has one of the function tables. There is also a panel on display at Perot Systems in Plano, Texas.

In 1997, a square chip of silicon measuring 0.25 inches (8 mm) on a side was built to the same functionality as the ENIAC, which occupied a large room. Although this 20 MHz chip was many times faster than the ENIAC, it was still many times slower than modern microprocessors of the late 90's.

Further reading


  • Berkeley, Edmund. GIANT BRAINS or machines that think. John Wiley & Sons, inc., 1949. Chapter 7 Speed—5000 Additions a Second: Moore School's ENIAC (Electronic Numerical Integrator And Computer)
  • Hally, Mike. Electronic Brains: Stories from the Dawn of the Computer Age, Joseph Henry
    Joseph Henry
    Joseph Henry was an American scientist who served as the first Secretary of the Smithsonian Institution, as well as a founding member of the National Institute for the Promotion of Science, a precursor of the Smithsonian Institution. During his lifetime, he was highly regarded...

     Press, 2005. ISBN 0-309-09630-8
  • McCartney, Scott. ENIAC: The Triumphs and Tragedies of the World's First Computer. Walker & Co, 1999. ISBN 0-8027-1348-3.
  • Tompkins, C.B. and J.H Wakelin, High-Speed Computing Devices, McGraw-Hill, 1950.


External links


  • ENIAC simulation
  • ENIAC-on-a-Chip
  • ENIAC from computing dictionary
  • Q&A: A lost interview with ENIAC co-inventor J. Presper Eckert
  • 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 the ENIAC, including the thought process behind the design.
  • Oral history interview with J. Presper Eckert, Charles Babbage Institute
    Charles Babbage Institute
    The Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....

    , University of Minnesota. Eckert, a co-inventor of the ENIAC, discusses its development at the University of Pennsylvania's Moore School of Electrical Engineering; describes difficulties in securing patent rights for the ENIAC and the problems posed by the circulation of John von Neumann's 1945 First Draft of the Report on EDVAC
    First Draft of a Report on the EDVAC
    The First Draft of a Report on the EDVAC was an incomplete 101-page document written by John von Neumann and distributed on June 30, 1945 by Herman Goldstine, security officer on the classified ENIAC project...

    , 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
    Charles Babbage Institute
    The Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....

    , 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
    Charles Babbage Institute
    The Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....

    , 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
    Charles Babbage Institute
    The Charles Babbage Institute is a research center at the University of Minnesota specializing in the history of information technology, particularly the history since 1935 of digital computing, programming/software, and computer networking....

    , 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.
  • ENIAC Programmers Project
  • The women of ENIAC
  • Programming the ENIAC
  • Programming example for the modulo function
  • How the ENIAC took a Square Root
  • Mike Muuss: Collected ENIAC documents
  • ENIAC chapter in Karl Kempf, Electronic Computers Within The Ordnance Corps, November 1961
  • The ENIAC Story, Martin H. Weik, Ordnance Ballistic Research Laboratories, 1961
  • ENIAC museum at the University of Pennsylvania
  • ENIAC specifications from Ballistic Research Laboratories Report No. 971 December 1955, (A Survey of Domestic Electronic Digital Computing Systems) issued in 1964 for ENIAC (TIFF images), also PDF version (18,305 kB, 207 pages)
  • A Computer Is Born, Michael Kanellos, 60th anniversary news story, CNet, February 13, 2006