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What was the first computer? | ENIAC - The first general-purpose electronic computer
This web site is devoted to ENIAC — “Electronic Numerical Integrator And Computer”. ENIAC was the first general-purpose electronic computer. It was made at the University of Pennsylvania’s Moore School of Electrical Engineering during World War II under the code name "Project PX". Physics professor John W. Mauchly and electrical engineer J. Presper Eckert led the team. Both were civilian employees whose computer work was funded by the United States Army Ballistics Research Laboratory. This is a collection of the best online information about the ENIAC and the people that created it. (The information is divided into these categories - Select a link or scroll down to read the blog.)

History and technology

People and stories

Was it the first computer?

UNIVAC and beyond

The ENIAC patent trial

Myths about ENIAC

ENIACtion on Facebook


Where to learn more

What was the first computer?

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The syntax is roughly based on the common MediaWiki syntax for footnotes, sick but uses the WordPress shortcode conventions. So, to include a footnote with the text "Text," you use:
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The Philadelphia Inquirer, sales March 6, sale 2000

By Kay Mauchly Antonelli

They were a most unlikely pair. They met at the Moore School of Electrical Engineering of the University of Pennsylvania. My future husband, John Mauchly, was 34, had a Ph.D. in physics from Johns Hopkins University and had just completed eight years as head of the Physics Department at Ursinus College. J. Presper Eckert, 22, had just graduated from Moore School and had stayed on as an electronics lab instructor while beginning work on his master's degree.

Before they left Moore in 1946, they had designed and built the world's first electronic computer, ENIAC, and laid the basic design for all future electronic computers.

In the summer of 1941, Mauchly took a course called Emergency Science and Management Defense Training at Moore. The laboratory instructor was Pres Eckert. Mauchly, who had a lifelong dream of forecasting the weather, was hoping he could learn enough advanced electronics to help him with the design of a computer that could speed up his statistical analysis of weather phenomena.

He couldn't have found anywhere a more receptive ear than Eckert's. Despite his youth, Eckert was a genius in vacuum tube circuitry. He already had a patent in the television field. The two men spent most of their spare time exploring the possibilities of computing electronically.

When the course was completed in September, Moore School offered Mauchly a teaching position. Mauchly was happy to accept. It meant not only an increase in salary, but also an opportunity to explore with Eckert the possibilities of designing and building some sort of computer.

War was declared on Dec. 8. Within six months, the Ballistics Research Laboratory of Aberdeen Proving Ground had taken over the operation of the differential analyzer (the largest mechanical calculating machine in the world), which was in the basement of Moore. Aberdeen also established a computing laboratory there, for which they hired and trained about 100 women. These women, called "computors," calculated trajectories to be used in Army firing tables. To compute only one trajectory, it took a computor 20 to 40 hours using an electric desk calculator.

Mauchly saw an immediate need for an electronic computer. In August 1942, he wrote a proposal titled "The Use of High Speed Vacuum Tube Devices for Calculating." He envisioned an electronic computer that could computer a trajectory in 20 seconds.

This proposal finally came to the attention of a young Army mathematician, Lt. Herman Goldstine, who asked for a full proposal. Eckert and Mauchly worked night and day for several weeks writing up a proposal that the Army accepted on April 12, 1943. The proposed machine would be called ENIAC, an acronym for Electronic Numerical Integrator and Computer. It was understood from the beginning that this would be a general-purpose computer.

Eckert was chief engineer and Mauchly consultant in charge of logic and design. With the help and dedication of about a dozen engineers, numerous wise men and assemblers, ENIAC was built on the first floor of Moore School. It had 18,000 vacuum tubes, was 80 feet long and could operate at 100,000 pulses per second.

ENIAC was demonstrated to the public on Feb. 14, 1946. It was a huge success. The New York Times reported "an amazing machine which applies electronic speeds for the first time to mathematical tasks hitherto too difficult and cumbersome for solution.. . . Leaders who saw the device in action for the first time heralded it as a tool with which to begin to rebuild scientific affairs on new foundations."

While ENIAC was being built, Eckert and Mauchly had many more ideas about how to build a smaller, cheaper, faster, more flexible machine, a stored program which they called Edvac. Forced out over a patent dispute, they left Moore School in March 1946 and formed their own company, Electronic Control Co., to build computers. Many of the engineers who had worked with them on ENIAC joined them.

Astonishingly enough, not a single bank or investment company was willing to lend them money. So with a loan of $25,000 from Eckert's father and the enthusiastic support of engineers willing to work for next to nothing, the new company was launched. The government gave them a contract to build a computer for the Bureau of Census, which they called Univac. Douglas Aircraft contracted for a small computer called Binac. Eckert was chief engineer, and Mauchly was president and salesman.

The government took a chance, and soon they had contracts to build Univacs for the Army, Navy and Air Force. The company, now renamed Eckert and Mauchly Computer Co., soon attracted the attention of an investor, Henry Straus, who was willing to invest time and money.

Just when things seemed promising, the company suffered two massive blows. First, Straus was killed in a plane crash. Then the McCarthy investigations charged the company with employing engineers who had communist leanings. The company lost its clearance for government work; all contracts with the Army, Navy and Air Force were canceled. As president of the company, Mauchly was charged with hiring communists and ordered off the premises. He fought back, demanded a hearing, and after two years was allowed back on the premises. After intensive investigations, the only charge against Mauchly was that he was "eccentric."

Meanwhile, the company, managing with a few civilian contracts and the Census Bureau contract, was sold to Remington-Rand, a manufacturer of punch-card equipment, typewriters and other office equipment. Eckert headed the engineering department, constantly developing new, faster and better methods for handling and storing data. Mauchly worked on machine languages and new programming methods. The two worked together all the time, with the dreamer Mauchly constantly coming up with ideas about what a computer should be able to do, Eckert constantly inventing hardware to make these things happen.

When his 10-year contract with Remington-Rand expired in 1960, Mauchly left to form his own company, Mauchly Associates, a construction management company. Eckert stayed with Remington-Rand as vice president of its Univac Division. Through its mergers with Sperry Corp. and later Burroughs, the company came to be called Unisys.

In 1971, Univac sued Honeywell for patent infringement. In the ensuing countersuit, the judge invalidated the ENIAC patents to Eckert and Mauchly, claiming, among other things, that the ENIAC was in public use more than a year before the patent was applied for. The testing of the machine by the Atomic Energy Commission was considered public use.

Eckert and Mauchly remained fast friends throughout their lives. They complemented each other. Mauchly was always the teacher - highly intelligent, witty and compassionate. Described by many as the "visionary of the computer age," he was interested in developing people as well as ideas. Mauchly died in January 1980 from complications of an inherited blood disease. Speaking at Mauchly's funeral in January 1980, Eckert said, "He inspired me and he inspired many others. He was not tied down by inhibitions or tradition. He was certainly one of the most brilliant people I ever knew."

Eckert stayed with the company he had cofounded and retired as vice president of Unisys. This brilliant, original, no-nonsense engineer and spellbinding speaker died in 1995, just a few months before the 50th anniversary of ENIAC. In his later years, he had become a spokesman for the computer industry. He claimed in his speeches that he and Mauchly were the Wright Brothers of computing. He was honored by the IEEE, Institute of Electric and Electronic Engineers, as "Engineer of the Century."


Kay Mauchly Antonelli, one of the first women programmers on the ENIAC, was married to John Mauchly for 32 years.  She died in 2006.

© 2000 Philadelphia Newspapers Inc.
The woman knew how to tell a story.  I just made a page for this piece, patient "Their Machine Launched a World of Change" by Kathleen Mauchly Antonelli.  It was printed in the Philadelphia Inquirer ten years ago.  Feel the love.
The woman knew how to tell a story.  I just made a page for this piece, sales "Their Machine Launched a World of Change" by Kathleen Mauchly Antonelli.  It was printed in the Philadelphia Inquirer ten years ago.  Feel the love.

A fascinating in-depth article by Peter Eckstein, cialis who is writing a book on the early years of a number of innovators, prostate including John Mauchly. It first appeared in 1996 and includes an extensive bibliography. (c) IEEE Annals of the History of Computing, Vol. 18, No. 1, 1996. Presented by permission of Peter Eckstein.
Amending the ENIAC Story, see John W. Mauchly, drugstore Datamation, troche Vol. 25, No. 11, 1979.


A Letter to the Editor of DATAMATION, from John W. Mauchly
[address] , Ambler PA, 19002

In the May 1979 DATAMATION, you published some highlights from Nancy Stern’s doctoral dissertation, in part relating to the “stored program”.  I would like to add further material which may interest some of your readers.
The EDVAC was the outcome of lengthy planning in which Eckert and I deliberately tried to overcome many problems of storage and control which were evident in the hasty “state-of-the-art” ENIAC System.  Much of this planning took place in the early months of 1944, when most of the ENIAC design had been frozen.  (See, e.g. “Disclosure of a Magnetic Drum Calculator”, Jan. 1944, U. Penna. Archives).
The principle which guided these “POST-ENIAC” efforts was that of trying, in the next computer, to use the same device for all situations requiring the same function (such as storage).  What had been out of the question with ring-counter storage suddenly appeared within reach because of the economies estimated as possible with the acoustic delay line storage.  It was not until October, 1944, that an Army Ordnance contract authorized work on EDVAC (without any specification as to just what an EDVAC might be).  We were still building ENIAC, and had to be sure that it was properly completed.  That took over a year more.
But all through 1944, and in 1945 as well, we were leading a “double life”.  For much of two shifts, 8 AM to Midnight, both ENIAC construction and testing needed supervision.  Then as hourly workers went home and project engineers “thinned out”, Eckert and I were left time to consider that “next machine”.  Naturally, “architecture” or “logical organization” was the first thing to attend to.  Eckert and I spent a great deal of thought on that, combining a serial delay line storage with the idea of a single storage for data and program.  From January, 1944, (the Magnetic Calculator Disclosure), followed by the delay line ideas of a month or so later, on through the Summer, Eckert and I were very busy in these dual roles --- switching from ENIAC jobs to thinking of what that new machine might be like.
During part of this time, Goldstine was hospitalized and did not have direct knowledge of the plans which were being generated so late at night.  But Harry Huskey, who came to the ENIAC project about April, 1944 (his estimate) confirmed that soon after he arrived he became aware that the “next computer plans” involved having programs and data in the very same “store”.  This was long before Goldstine met von Neumann in August, 1944.
September 7, 1944 was the first day when von Neumann had security clearance to see the ENIAC and talk with Eckert and me about the classified digital computer projects on which we worked.  When von Neumann arrived, Eckert and I were asked to tell “Johnny” what our plans were, and we did. We started with our simple basic ideas: There would be only ONE storage device (with addressable locations) for the ENTIRE EDVAC, and this would hold both data and instructions.  All needed arithmetic operations would be performed in just ONE arithmetic unit (unlike the ENIAC).  All control functions would be centralized (in contrast to the ENIAC).  Of course there would be devices to handle input and output, and these would be subject to the control module just as the other modules were.
Johnny learned instantly, of course, as was his nature.  But he chose to refer to the modules we had described as “organs” and to substitute hypothetical “neurons” for hypothetical vacuum tubes or other devices which could perform logical functions.  It was clear that Johnny was rephrasing our logic, but it was still the SAME logic.  Also, he was introducing different but equivalent symbols; nevertheless the devices still did the same things.  Johnny did NOT alter the fundamental concepts which we had already formulated for the EDVAC.
Everyone could see how fascinated Johnny was with a subject which had somehow escaped his amazingly wide interests until Goldstine told him of the Moore School project.  Like a child with a new toy, he could not put it aside.  When his consulting duties required him to visit the Manhattan Project, he took off for New Mexico, hut his mind was on our EDVAC architecture.
He must have spent considerable time at los Alamos writing up a report on our design for an EDVAC.  This MSS he sent to Goldstine, with a letter stating that he had done this as an accommodation for the Moore School group who had met with him.  But Goldstine mimeographed it with a title page naming only one author --- von Neumann.  There was nothing to suggest that ANY of the major ideas had come from the Moore School Project!
Without our knowledge, Goldstine then distributed the “design for the EDVAC” outside the project and even to persons in other countries.
Small wonder, then, that computer history gave von Neumann the credit.  Eckert and I, who left the Univ. of Penna. In 1946, no longer had access to the documents which might have helped to show “who did what, when.”  But after many years, litigation has unearthed some of those documents, and historians can read what was once classified.  But, even after declassification, those reports are not accessible to most people, since they were reproduced in such small quantities.  Nevertheless, we hope that more historians will refer to them.
Of those who did check our ENIAC and EDVAC reports, Metropolis and Worlton published “A Trilogy of Errors in the History of Computing” (USA – Japan Computer Conf. 1972 AFIPS).  Metropolis of los Alamos was in an excellent position to notice such errors, for he knew von Neumann and Eckert and me and the history recounted above.  But on “historians” who merely copy from popular sources, that paper had no influence.
Before moving on to the BINAC, it is important to note that the ENIAC really did have a stored program, but not in the sense in which that word is currently used.  The ENIAC was much more than an analog of a mechanical desk computer.  Control of the calculations was more important than “just doing arithmetic fast”.  And that control had to be fast enough so that it did not lose all the time gained by doing the arithmetic fast.  That meant that any element of the program which changed fast had to be “in fast storage”.  Each of the 20 “accumulators” had a ring counter for “repeat operations”, but more important were the electronic counters and stepping switches in the Master Programmer.  These made possible immediate change from one program sequence to another, enabling the use of nested subroutines and other program variations.
Altogether, about 25% of the ENAIC “fast electronic storage” was devoted to such internal storage of those parts of the program which varied rapidly.  That is one of the important features which made the ENIAC a far more powerful instrument than an “electronic speed-up of a mechanical computing device”.

Now for a few words about the BINAC, which was not only the first stored program computer built by Eckert-Mauchly, but the fastest with delay line storage.  Its clock rate was 4 megacycles, or 8 times that of the first machine at Cambridge, England --- the EDSAC.  The BINAC was really two identical machines, checking each other each clock cycle, and these “Siamese twins” were completed and amply demonstrated for an entire week to many scores of guests in Philadelphia.  These demonstrations were reported in the Journal of the Franklin Institute for October, 1949, but not much carried by the popular press.  They were very carefully noted by observers from the National Bureau of Standards, and the Bureau of the Census, because these agencies were expecting Eckert-Mauchly to build and deliver UNIVACs to the government.  Apparently these highly interested groups were satisfied that Eckert-Mauchly would indeed be able to produce UNIVACs.
Then what happened?  It would be more than a year before any computer of similar capacity and speed would be available in North America.  ENIAC, for three years the ONLY electronic computer in the whole world, now had a real rival with 512 “words” of storage any of which could be used for data or program.  Northrop, the BINAC contractor, did not see or realize the potential of what it had.  While ENIAC was kept busy on many scientific problems until 1955, this pioneer BINAC of 1949 was cast aside.
Northrop Aircraft required immediate delivery in Philadelphia.  Northrop then “took charge”.  The various modules of the BINAC were roughly crated, shipped to California, and apparently ignored.
But, for the sake of “stored program” history, the following should be recorded: The first of the two computers which became the BINAC was under test early in 1949, and ran non-stop without error in April, 1949, for 44 hours.  The test was then interrupted so that the engineers could get on with other work.  The Cambridge EDSAC, we are told, made its debut in May, 1949.
Having covered some of the main points, I shall conclude with a few minor comments.
One common misconception which Eckert and I have repeatedly tried to correct is that ENIAC technology was based on previous radar work.  There is not a shred of truth in that.  It was, to a large extent, based on the “scaling” circuits of nuclear and cosmic ray laboratories.  The acoustic delay line storage device, used in EDVAC, BINAC, and UNIVAC came from Eckert’s previous projects for radar.
There is a confusion of p.233 of Dr. Stern’s article between fixed function tables used in the multiplier unit to produce “partial products”, and the three large “portable function tables” which could be manually set up for arbitrary function values for 104 arguments.
Also, I should answer Fred Gruenberger’s remarks about my August 1942 memo.  It was never intended to explain or propose a CONTROL method for electronic computation, but merely to “sell” the reason for developing electronic devices to overcome the limitations of mechanical devices, including relays.  Fortunately it did that.  But IT DID NOT DESCRIBE even a calculator, still less a computer.
Any one who wants to read what we proposed for the ENIAC should consult the April 1943 proposal which Eckert and I and Dr. Brainerd put together and presented to the Ballistic Research Laboratory at a meeting which approved the “starting project”.  In that document was a “program chart” which I drew up to show how the iterations for a trajectory might be calculated.  Such may be the first program ever attempted for an electronic digital device.  Perhaps Brian Randall will reprint that proposal in a revision of his book on “Origin of Digital Computers”.
A History of the Univac Magnetic Tape Plating Facility
Located in the Basement of the Building at 3747 Ridge Avenue, sickness
Philadelphia, cialis sale Pennsylvania

Douglas C. Wendell, doctor Jr.                                                                      July 2005     rev 9/27/06

The work in the basement of Ridge Avenue was the culmination of the first project I was assigned to. Ted (Theodore H.) Bonn was doing research aimed at developing a process for making magnetic recording tape by coating a non-magnetic metal supporting tape with a thin magnetic metal coating–the idea being that a thin coating would be capable of recording a higher data density than possible on the thicker iron oxide coating then used on recording tape.  Another important consideration was that a metal-based tape would be mechanically stable, unlike the paper based recording tape then in use.

I was hired in November of 1947 at The Electronic Control Company located at 1215 Walnut Street in the several floors above a Lane Bryant store.  I was interviewed by John Mauchly, J. Presper Eckert, Isaac Auerbach, Frazer Welsh, Ted Bonn, and John Sims.  They decided to take a chance on me, liking my combination of a degree in chemistry from Haverford College along with my electronics training and service as an electronic technician in the navy during WWII.  I was assigned as a chemist to assist Ted Bonn who is an electrical engineer.  My job was to provide additional chemical expertise for the magnetic alloy deposition project that Ted was working on.  I had theoretical knowledge of electrochemistry, but no direct experience in electroplating.  I studied the literature Ted provided: an elementary textbook on electroplating by Blum and Hogaboom and a practical book, The Metal Finishing Handbook published by Metal Finishing magazine. Bernie Victor was our capable lab technician.  Our chemistry laboratory unceremoniously resided in the second floor lavatory.

Ted Bonn had found two interesting processes in the patent literature for depositing nickel-cobalt alloys that might be useful as magnetic recording surfaces.  When I was hired, he was investigating one non-electrolytic process (commonly known as an electrolysis process) which used a chemical reducing agent to deposit a layer of nickel-cobalt onto strips of copper tape. This process required a near-boiling aqueous solution with a short useful working life, and also required that the plated sample be heat treated in hydrogen in order to improve the magnetic properties. The resulting test tapes had magnetic properties which varied along the length of the tape. The other plating method being considered was a more conventional nickel-cobalt electro-plating process with a special modification that superimposed an alternating current onto the normal direct current. In this process, the superimposed alternating current is larger than the direct current, a process sometimes used in decorative plating to produce a brighter surface.  Although somewhat encouraging, neither process provided the desired magnetic properties.
We tested the magnetic properties of our samples by plotting the magnetization loop on a B-H hysteresis loop tracer which Ted had built.  The result was displayed on an oscilloscope.  The most promising results came from the electrolysis process with the hydrogen heat treatment, but converting this uncertain process to continuous tape production didn’t seem feasible. We only ran a few experiments with the electrolysis process after I started work. Ted decided we would concentrate on the electroplating process with superimposed A.C.  After some weeks of indifferent success, Ted proposed combining the two processes--trying a combination of superimposed A.C.  electroplating with the chemical reducing agent from the electrolysis process. We made a little progress so it seemed worthwhile to continue with the combined process.  I decided to add an additional component to stabilize the plating bath, a buffer chemical making it more like some commercial plating baths described in the text books.  Ted had initially used the composition given in the patent.  The tests were tedious, because for each bath composition tested, we had to vary five major parameters: temperature, pH, current density, the ratio of direct current to alternating current, and the amount of the reducing chemical.  In each experiment, we plated five test tapes, varying the A.C. to D.C. ratio for each tape with the other variables constant. I decided to include a control test with each experiment, plating a sixth tape with just direct current--no superimposed A.C.  Ted had already tried straight D.C. with the plating bath described in the patent, but the result was uninteresting.  We ran the next set of tests with the reducing chemical and the buffer salt and included a control test with no A.C.   The first five samples, run with different current densities of both A.C. and D.C. showed no significant improvement, but when we saw the test loop for the control tape, just D.C., we got the kind of thrill that happens when your underdog sports team unexpectedly wins its game.  We repeated some of the earlier experiments, this time using just direct current and we obtained a repeatable range of magnetic properties that would provide the recording engineers with a selection of values to work with.

We had run over 500 tests before we found the properties we were looking for. We used the last few tests to optimize the plating process.  Our development work was now finished and we were ready to try the plating process on a large scale. Our patent attorney, George Eltgroth filed the patent application while we were still at Walnut Street and it was issued in three or four years (about average). The Bonn-Wendell patent became widely investigated and was used by various companies in the computer industry in the production of tape, disks, and drums for many years.

Here’s an interesting note: at a meeting of the Electrochemical Society 15 or so years later, I was startled to find that we were famous--at least in my little specialized field. I received the accolades since I was working as an electrochemist, but we were both recognized as pioneers by workers in other companies in the magnetic data recording field. This was years after I had switched into other work.  Later, at Burroughs, I received patents in various areas: metal etching, a digital logic device, a magnetic memory element formed from a thin strip of permalloy, and an electrostatic memory storage element.

With the chemical work done, the next task, or rather project (consisting of many tasks) was to design and build a tape plating machine with its supporting apparatus. Then in early 1948 the Electronic Control Company became the Eckert Mauchly Computer Corporation and we moved to the building at Broad and Spring Garden Streets.  There was no longer a need for electro-plating experiments, but there were months of design and parts fabrication to be done for the plating machine. The design was a team effort and in the end, fifteen or twenty persons were involved, but these are the people I especially remember: Ted Bonn of course, and myself, also electrical engineer Frazer Welsh, Frank Tees and his draftsman Bill Boss, mechanical engineer Bob Roedder and his machinists as well as Pres Eckert and John Mauchly who provided valuable design advice and monitored progress.  The purchasing department under Enea Bossi and his purchasing agents, notably Eddie Whiteman and Bob Newton, did a great job obtaining unusual items--for example parts made of special corrosion resistant alloys.  Ted Bonn went back to doing electronic design work and I assumed the task of coordinating the design, and construction of the machine and its auxiliary apparatus, and later on managing supplies and training operators.  The initial design effort had begun while we were still in the Walnut Street building and continued on Ridge Avenue.

As we worked on the preliminary design of the tape plating machine, the space requirement for the plating operation became apparent as well as the need for water and the disposal of waste water.  Installing such an operation in the Spring Garden Street building (or any conventional office building) would have been a major project, even assuming we were able to get permission from the owner.  We did set up a very small plating laboratory in order to do some chromium plating and other types of plating for wear resistance on magnetic recording heads and corrosion resistance on some small parts.

I wasn’t very busy during the early design stage while we were at Broad and Spring Garden and I received an interesting assignment: go to the Franklin Institute Library and read and report on some articles on the work Dr. Shockley was doing at Bell Labs.  So I reported about the work on transistors.  I remember reporting that it looked promising but there was a long way to go before transistors would be available for computers.

The Yellow Cab Company acquired the Broad and Spring Garden Streets building and became our new landlord soon after we had moved from Walnut Street in 1948.  Not very long after that, some time in 1948 or 1949, Eckert-Mauchly had outgrown the space in the Yellow Cab Building which made installing the plating machine in the Spring Garden building moot.  We obtained a release from Yellow Cab allowing us to vacate under reasonable terms, and we moved to a vacant knitting mill on Ridge Avenue between Allegheny and Lehigh Avenues.

I learned from Pres that had Yellow Cab not agreed to the release, we would have obtained a “contract” to test automobile horns 24 hours a day or something similar. Another observation about the Yellow Cab operation: the taxicab dispatch transmitter signals were picked up by the BINAC circuits which then had to be shielded.

An important early decision was that the magnetic properties of the plated tape must be continuously monitored during the plating process.  This meant that at the end of the plating line just before spooling, the finished tape had to pass thru a B-H hysteresis loop tracer.  The design of the in-line B-H loop tracer was discussed at length by Pres Eckert, Frazer Welsh, Ted Bonn, and me.  Ted Bonn’s loop tracer used two alternating current magnetizing coils with two sensing coils, into one of which our tape samples were inserted--the other sensing coil being used to neutralize the air induction in the first coil.  The magnetizing coils got very hot, so the B-H loop test had to be done rapidly and the magnetizing current switched off before the coils burned up.  The loop tracer on the plating machine was expected to run continuously, so overheating could be a serious problem.  From elementary text book theory, the magnetizing field strength in a coil of fixed dimension depends on ampere-turns--the product of current times the number of turns of wire.  Therefore it didn’t matter whether we used many turns with a small current or a few turns with a large current to get the required field strength.  We decided to go with magnetizing coils of about 50 turns of copper tubing, using a high current, and cool the conductor by running water through it.

Pres and I shared an amusing incident relating to the design of the production continuous loop tracer.  He became concerned that the Philadelphia water supply pressure might not be enough to cool the coils adequately. I found a pressure gauge and Pres and I went down to the basement to check.  I attached a heavy hose to the gauge and held the hose against the water faucet and turned the handle.  We just had time to observe the pressure when the hose got loose and squirted us.  It got a laugh from both of us.  (The pressure was around 50 PSI, much higher than needed.)

The availability of a large basement at Ridge Avenue solved the problem of where to put the tape plating facility. The large electroplating room became my domain until around the beginning of 1952 when George Sutton became foreman over the production team.  My technician during much of that time after the plating machine was built was Robert Laurens, a Belgian who had been a merchant ship sailor during WWII, and who was a good mechanic and chemical technician. Eventually, with tape production running smoothly, I was released to the engineering department for development of plated memory disks.  I worked for Reed Stovall on that project until I resigned in the spring of 1952 to work for a chemical company for a year before joining Burroughs in 1953.

I forget how many months elapsed before we had the tape plating machine running, but it was a very interesting period.  We created a concrete-lined trench in the concrete floor to drain waste water from the plating process rinse tanks.  A student summer helper (a neighbor of Frazer Welsh’s, last name: Ryan) and I learned to operate a jackhammer for opening up the trench. (The Good Lord preserved our hearing, I know not how, and I still sing in choirs and choruses. The first chorus we sang in had just been started by our technical writer, Joe Chapline, organist and choirmaster at St. Peter’s Episcopal Church in Mt. Airy, Philadelphia.)

My young helper and I continued to get the area ready to hold the plating machine and when we got the main structural elements from the shop we assembled the framework of the machine.  Some of the smaller parts had already been made at the Spring Garden Street plant, and as more finished parts became available, we completed the assembly.  I suppose there were more than a thousand parts.  I ordered the chemicals and other expendable supplies.  It was sometime late in 1948 before we were able to run the machine to test its ability to handle tape.  My high school friend and helper had started college before he had a chance to see the finished machine.

Electroplating requires direct current electrical power.  While still at Spring Garden Street, I had calculated the required current and voltage and with advice from Pres Eckert I designed a power supply using heavy transformers bought from a war surplus store nearby on Callowhill Street.  We had learned the Ridge Avenue plant was supplied with two phase power (I suppose, half a century later, they may have converted to the now ubiquitous three phase power).  I explained to the store owner how we were going to use the transformers in a two phase bridge rectifier circuit which he claimed wouldn’t work.  I guess I told him not to worry, I knew what I was doing, and of course it worked fine.

We knew that the chemical composition of the plating bath would change with use and would have to be monitored. We obtained an instrument for measuring the solution pH and I set up a chem. lab in which we could periodically analyze the plating solution.  The plating solution which Ted and I had developed at Walnut Street, used nickel and cobalt chlorides buffered with ammonium chloride and with the ingredient sodium hypophosphite–the special ingredient controlling the magnetic properties of the deposited alloy.  The critical nickel-cobalt ratio of the plating bath changed with time and had to be periodically corrected.  Chemical control of the plating process was comparatively easy and the laboratory became available for other chemical problems arising in the plant.

The phosphor-bronze base tape was one mil (one thousandths of an inch) thick and half an inch wide. It had the strength, flexibility, and smoothness required for the tape handling units–then under development by Bob Mock and Ned Schreiner under Frazer Welsh.  The thickness of the plated surface was a bit less than one tenth of the base tape thickness (0.08 mil).  We never measured it directly, but calculated it from the difference in weight between a sample of tape before and after plating.

Much earlier, when first working with the electroplating bath combined with the reducing chemical, Ted and I had wondered if the addition of the reducer would cause additional metal deposition beyond what would be expected from Faraday’s Laws of Electrolysis.  We included in some of our measurements of plating thickness, measurements of current and time, calculating the weight of metal to be expected.  The answer is that the addition of the reducing agent did not cause significant additional deposition as measured by the ordinary laboratory equipment in our lab.

The plating machine had to move great lengths of phosphor-bronze tape through seven different baths.  The tape was conducted through each cleaning and rinsing bath on a frame holding two stainless steel rollers.  The photo shows the arrangement of the frames and the diagrams show how the tape moves over the top roller then down and under the bottom roller and up again to the top roller.  The bottom roller was angled enough to offset the tape by a little more than its half inch width so the return of the loop came up alongside the previous loop.  In the actual machine, there were fifteen loops.  I was reminded by Ted Bonn after he read the first draft of this paper that the idea for setting the top and bottom rollers at an angle came from Frazer Welsh.

The frame and the bottom roller that dipped into the plating bath were made of a non-conducting material to prevent alloy being deposited on them.  The second plating machine had two frames in the plating bath allowing twice the plating speed.  All the upper rollers were kept above the liquids in the tanks.  The upper rollers above the plating bath were of a special metal alloy to prevent corrosion by the plating bath and still conduct the current required for the electroplating process.

The photograph of the tape-plating machine shows it not in use, with the working parts out of the tanks which can be seen in back of the tape handling mechanisms.  The machine was raised and lowered by a small electric motor helped by the heavy cast iron counterbalance weights that can be seen in the photo.  When not in use, or when being serviced, the raised machine is rolled on tracks away from the tanks.   Eventually, the plating machines were moved to the Pep Boys Building on Hunting Park Avenue where the photograph shown was taken.

After I became a Burroughs employee, I visited the plating room at the Pep Boys building during an open house at the Sperry Rand plants in Philadelphia when the I.E.E.E. (an engineering society) held a meeting in Philadelphia.  My friend, George Sutton, the foreman of the plating shop was describing the operation of the plating machines to guests when his voice failed and I relieved him for about half an hour while he rested his voice.

The picture of the plating machine came from a Sperry-Rand brochure from the 1970s–an employment promotion for hiring engineers mailed to me around 1970.  I did return to Sperry in 1979, but as a programmer and worked there two years before returning to Burroughs not long before the merger with Sperry Univac.  I did get to meet Herman Lukoff and Pres Eckert in my second term at Univac and I was there when, sadly, both John Mauchly and Herman died, and attended both services.

What a learning experience those years were for me!  I learned a ton of stuff about all kinds of electroplating there, which was a great help when I went to Burroughs.  I learned a lot about corrosion resistant materials as well as mechanical and electrical design.  I had to learn how to manage and train a crew of operators.  And, in celebration of a most memorable occasion in July of 1949, six people from the Ridge Avenue plant (plus six wives or husbands) traveled to Morristown, New Jersey to attend my wedding to Nancy Carpenter.

For 25 years I did design, engineering, and laboratory research work in chemistry and physics. I finally switched into programming in 1972, starting at hardware level (microprogramming).  Later I programmed in machine languages, and finally in the high level languages Pascal and Algol. During my two years at Univac from 1979 to 1981 I did only microprogramming.  I retired in 1991 from both Burroughs and Univac simultaneously (Univac and Burroughs had merged in 1982 to become Unisys).  My final assignments at Unisys were to write instruction manuals for several machine level computer programs.

When I returned to Univac in 1979 after working 26 years at Burroughs, I renewed my friendship with Tony Occhiolini who then kindly provided me with the three staff pictures of the early days (1948) from the company archives. The pictures were taken at the Eckert-Mauchly plant at Broad and Spring Garden Streets shortly before the move to 3747 Ridge Avenue.  I also want to thank Ted Bonn for helping me get started.  I thank the many friends I worked with for welcoming me back when I returned to Univac in 1979.

The tape was moved at a speed of around six inches per second (twelve for the second machine) by a motor that turned the top roller (or rollers) over the electroplating bath.  The take up spool was turned by a motor with enough torque to just keep the spool turning.  Also several roller stations before the plating bath were powered by motors controlled by sensors in order to prevent damage from excessive tension on the tape.

A variable power supply capable of supplying up to six volts was designed using two war surplus transformers; each connected to one phase of our two phase power lines.  High current rectifiers were connected in bridge circuits which had the advantage or reducing the 120 cycle ripple.  We were concerned that the ripple might cause a problem in plating, but that was not the case.  The net ripple was less than 20%.

A similar transformer operated the water cooled magnetizing coils for the B-H hysteresis loop tracer.  The oscilloscope for monitoring the B-H loop can be seen next to the Tape Plating Machine.

The tape plating machine electroplated a nickel-cobalt alloy about .08 mil (.00008 inch) thick on a base  tape of half inch wide phosphor bronze, one 1 mil (.001 inch ) thick.  It plated at a rate of approximately one foot per second on the machine shown. The finished tape was re-spooled onto conventional computer tape reels for computer data storage.  This machine was the larger of the two built, having twice the tape speed of the first machine.  Both machines were moved from Ridge Avenue to the Sperry Rand facility leased from the Pep Boys Company on Allegheny Avenue.
The myth of von Neumann's ENIAC involvement is perpetuated in Harpers Magazine, cialis Jan 2006, "Owning the weather" by Ando Arike
Eckert Mauchly 3747 Ridge Ave, search Little Linden, Trappe near Ursinus?

Excuse me (Bill Mauchly) for being thrilled see Peter Eckstein totally demolish Jane Smiley's The Man Who Invented the Computer: The Biography of John Atanasoff, ed Digital Pioneer in the Columbia Journalism Review.  See the review and comments here.

The review of the book by Lauren Kirchner first appeared online Nov 24, 2010.  The entire trail of comments is very entertaining in itself.   Gini Calcerano dove in to criticize the book.  Then in a surprise visit by Jane Smiley herself, the author tries to throw the fight in a different direction by accusing a Gini Calcerano of hiding the fact that she was actually a Mauchly, and even better, a "Mauchlyite."  Yea, the Mauchlyites were awakened and hit back with renewed force.  As Rick Moranis says in Ghostbusters: "Many Shuvs and Zuuls knew what it was to be roasted in the depths of the Slor that day, I can tell you!"

Today Peter Eckstein, author and historian, added a highly detailed criticism of Smiley's factual errors and extreme bias.  Here is his post in its entirety:


I am not related to anyone in this controversy, and I never met Mauchly.  I did interview Eckert (and others) extensively and published a long article on his early life in IEEE Annals of the History of Computing. My only strong bias is a belief that history should be depicted as accurately as possible.  I have read all parts of the Smiley book concerning American computer developments and found them to be superficially researched, riddled with factual errors, and totally biased—nothing short of a publishing scandal.

Smiley’s thesis is entirely borrowed from previous writers on one side of the issue.  It is that Atanasoff, a brilliant scientist at Iowa State (where Smiley taught for more than a decade), invented “the computer,” later called the ABC.  Then his ideas were stolen by Mauchly (“a space case”) who shared them with Eckert at Penn. Eckert merely “followed through,” making sure that Mauchly’s designs “were properly executed” during World War II in developing the ENIAC computer for the Army. By contrast, many serious computer historians argue that Eckert, who worked closely with Mauchly and others, should be seen as the master engineer of the computer age.

The portions of Smiley’s work dealing with the American developments rely overwhelmingly on just three second- or third-hand book treatments and an interview with a filmmaker. She directly quotes no documents and offers only one quote from any of the dozens of relevant oral histories—and this one derives from a secondary source. (The only portions of her book that add anything to the record are the oral and written contributions by computer scientist Gustafson.)

No wonder, then, that Smiley’s limited research produces well over a dozen factual errors. For example, the two ENIAC leaders met while Eckert was a lab assistant in a prewar crash course in electronics in which physicist Mauchly was a student.  Smiley, however, treats them as “lab partners” in a course “in computing theory”—a subject which essentially did not exist in 1941. She says Eckert only had a bachelor’s degree by age 27, when he actually had a master’s by age 24. She incorrectly states that Mauchly “had run the UNIVAC division until 1959”, when he only ran an applications center within it.  She twice cites a statement about the two men’s characteristics, once attributing it to Mauchly’s widow and once to Eckert’s. There are many, many more such errors, along with some frightfully biased innuendos and interpretations. Feel free to ask me for a list.

Over three decades Annals has published dozens of relevant articles.  Smiley cites only two—and only one directly. If she had bothered to look, she would have found, for example, two articles by Calvin Mooers.  He was a top assistant to Atanasoff when, shortly after the war, the Navy gave him the responsibility and resources to develop a new, post-ENIAC computer. Mauchly was a part-time consultant, and the working engineers welcomed his “advanced technological ideas,” especially since they were “not getting intellectual support” or “leadership of any credible sort” from Atanasoff.  When pressed for a decision, he would invariably go off on long digression on topics like the health benefits of goats’ milk.  After a year the Navy gave up on the project, which contributed nothing. Smiley shows no awareness that such evidence even exists.  Indeed, she alleges that Atanasoff, “because of his energy, organizational skills, and persistence,” had a long life of “mastering everything he tried.”

Atanasoff was undoubtedly an ingenious man, and this is reflected in his design of the ABC. However, when Smiley adopts for her title "The Man Who Invented the Computer," it must be difficult for her to allow for any nuance or embarrassing contradictions to this story. This is a book that should never have been commissioned (by the Sloan Foundation), written (by novelist Smiley) or published (by Doubleday). Sloppy, sloppy, sloppy.

Peter Eckstein
ENIAC was a good and useful computer for its time. But it wasn't long before other computers eclipsed it. Mauchly and Eckert started planning a better computer, click EDVAC (Electronic Discrete Variable Automatic Computer) before ENIAC was finished. They left the Moore School (and EDVAC) in 1946 and formed the Electronic Control Company, prescription doing business as Eckert-Mauchly Computer Corporation -- this was the world's first commercial computer company.

EMCC's first completed computer was BINAC (Binary Automatic Computer) for the Northrop aviation company followed by UNIVAC (Universal Automatic Computer) for the U.S. Census Bureau. Several UNIVAC models followed. The company also innovated the modern sense of "programming" a computer.

The brand continued as EMCC was acquired by Remington Rand and became its UNIVAC division in 1950. Remington Rand also brought in Engineering Research Associates in 1952, merging it with the UNIVAC group. Remington Rand itself merged with Sperry in 1955, become Sperry Rand.

More recently, the company became Sperry Corp. in 1978 and merged with Burroughs Corp. in 1986. The merged company took the name Unisys, which it uses today.


BINAC: A Case Study in Technology (IEEE Annals of the History of Computing) - Solid article about EMCC's first completed computer

Coming to Grips With UNIVAC (IEEE Annals of the History of Computing) - What made the UNIVAC successful in the Air Force

Programming on the UNIVAC I: A Woman's Account (IEEE Annals of the History of Computing) - Comparisons vs. using ENIAC and what it was like for women working in the new computer field

UNIVAC Short Code (IEEE Annals of the History of Computing) - Article about UNIVAC's programming language


From ENIAC to UNIVAC: An Appraisal of the Eckert-Mauchly Computers (Nancy Stern) - "The bible" of early UNIVAC history

Unisys Computers: An Introductory History (George Gray, Ronald Smith) - An excellent overview of all of the UNIVAC computers from the 1950s-1980s


Unisys History Newsletter (George Gray) - Tales from insiders about the UNIVAC and the business of selling them

UNIVAC History Conference (Charles Babbage Institute) - A discussion panel with a large number of UNIVAC role players

The information on this site covers ENIAC, viagra who made it and why they did so, hospital its context vs. other early computing devices, ailment what it led to, and the Honeywell v. Sperry Rand patent trial. However there is always more to learn, and even in the 21st century ENIAC remains a favorite topic among historians. Below are some links that will provide greater context for advanced learners.


Celebrating the Birth of Modern Computing: the Fiftieth Anniversary of a Discovery at the Moore School of Engineering of the University of Pennsylvania (IEEE Annals of the History of Computing) - A retrospective article from a milestone year

Computers and Society Fifty Years after ENIAC (IEEE Technology and Society) - How did ENIAC change the world?

Computer Tree (ENIAC as the root of modern computers) - Famous visual representation of ENIAC and the computers it spawned

Designing Reliable Systems With Unreliable Components (IEEE Micro) - Engineering perspective about technical challenges

ENIAC Influence on Business Computing, 1940s-1950s (IEEE Annals of the History of Computing) - How did commercial systems compare to and learn from ENIAC?

ENIAC, the Verb “To Program” and the Emergence of Digital Computers (IEEE Annals of the History of Computing) - ENIAC's long-term effect on the field of computer programming

Origins of Modern Computing (Saul Rosen article) - Famous overview article reprinted on this site

Trilogy on Errors in the History of Computing (IEEE Annals of the History of Computing) - ENIAC was not always so well understood


Bit by Bit: An Illustrated History of Computers (Stan Augarten) - Solid lay overview for the image-conscious

Calculating a Natural World: Scientists, Engineers, and Computers During the Rise of U.S. Cold War Research (Atsushi Akera) - Academic history that covers ENIAC's role in world affairs

Engines of the Mind: The Evolution of the Computer from Mainframes to Microprocessors (Joel Shurkin) - Lay history book

Computers and Commerce: A Study of Technology and Management at Eckert-Mauchly Computer Company, Engineering Research Associates, and Remington Rand, 1946-1957 (Arthur Norberg) - Academic coverage of the UNIVAC generation

Creating the Computer: Government, Industry, and High Technology (Kenneth Flamm) - Academic history of the outside factors on computers like ENIAC

Digital Computer Engineering (Harry Joshua Gray) - Very technical book about how early computers including ENIAC work

From Dits to Bits: A Personal History of the Electronic Computer (Herman Lukoff) - Autobiography of an engineer who worked on ENIAC and at EMCC

Giants Brains; or, Machines That Think (Edmund Berkeley) - Landmark book describing how computers work and how they could help ordinary people

Introduction to Automatic Computers (Ned Chapin) - Technical overview of computing in the 1950s

This page has links to resources about the people in the ENIAC story.

John Mauchly and Pres Eckert conceived of ENIAC and led its design.  Like most great scientific advancements, it was the result of a large team effort.

The resources at the links below describe the extensive engineering and scientific effort involved in "Project PX", see along with the personal stories of many behind-the-scenes civilians and Army staff who helped bring ENIAC to life.

ENIAC team

People, Machines, and Politics of the Cyber Age Creation (Barnes and Noble Nook book) (read the forward here) - Book by Rocco Martino who was a colleague of Mauchly

Their Machine Launched a World of Change (Kay Mauchly Antonelli article) - Insider perspective of the life impact of ENIAC

Oral history with J. Presper Eckert, Kathleen Mauchly, William Cleaver, and James McNulty (Charles Babbage Institute) - Interview with some of ENIAC's players

Case Files: Eckert and Mauchly (Franklin Institute) - Good lay overview of the inventors

Panel discussion with Kay Mauchly, Herman Goldstine, Dave Mackey, Richard Clippinger and John Brainerd (IEEE Global History Network) - Another good interview with a variety of important ENIAC players

The Women of ENIAC (IEEE Annals of the History of Computing) - Focuses on the women who were ENIAC's programmers

Oral history with Jean Bartik and Frances Holberton (Smithsonian) - Focuses on important ENIAC programmers and their careers

ENAIC Programmers Project (Kathy Kleiman) - A video documentary about the programmers

Top Secret Rosies (Site about female "computors" in World War II)

John W. Mauchly

Oral history: Part 1, Part 2, Part 3, Part 4 (Smithsonian) - Comprehensive interview

Fireside Chat (IEEE Annals of the History of Computing) - Mauchly speech

Mauchly Tribute (Tay Hayashi) - Memories of a student of Mauchly's

Biography (IEEE Global History Network) - Overview for a lay audience

The Computer and the Skateboard (Paul David, Jim Reed) - Documentary about Mauchly and his eccentric personality

John Mauchly's Early Years (Kay Mauchly / IEEE Annals of the History of Computing) - Insider account of Mauchly's life leading up to ENIAC

As the Twig is Bent: the Early Life of John Mauchly (IEEE Annals of the History of Computing) - Article about Mauchly's youth and how it shaped him for making computers.  Also available here.

J. Presper Eckert

Oral history (Charles Babbage Institute) - Comprehensive interview (link went bad)

The lost interview (Computerworld magazine) - Another solid interview

Biography (IEEE Global History Network) - Overview for a lay audience

J. Presper Eckert (IEEE Annals of the History of Computing) - Article about Eckert's youth and how it shaped him for making computers.  Local copy here: pdf

Jean Bartik

Interview (About.com) - Overview for a lay audience

John Grist Brainerd

Biography (IEEE Global History Network) - Overview for a lay audience

John G. Brainerd and Project PX (Proceedings of the IEEE)

Arthur Burks

Oral history (Charles Babbage Institute)

Oral history with Alice Burks (Charles Babbage Institute)

Oral history (IEEE Global History Network)

Adele Goldstine

Biography (IEEE Global History Network) - Overview for a lay audience

Herman Goldstine

Oral history (Charles Babbage Institute) - Comprehensive interview

Harry Huskey

Oral history with Velma Huskey, Part 1 (Smithsonian) - Comprehensive interview

Oral history with Velma Huskey, Part 2 (Smithsonian) - Comprehensive interview

Kathleen "Kay" Mauchly

Biography (IEEE Global History Network) - Overview for a lay audience

Irven Travis

Oral history (Charles Babbage Institute) - Comprehensive interview

John von Neumann

John von Neumann's Influence on Electronic Digital Computing (IEEE Annals of the History of Computing) - The man behind the so-called "von Neumann architecture"

John Vincent Atanasoff

Iowa State's Computer Science has a website "devoted"  to John Atanasoff.    It is a fairly complete collection of the pro-Atanasoff literature.   Part of the motivation to create this site is to counter that well organized propaganda campaign.
Was ENIAC the first computer? The answer depends on the definition of "computer". A number of prior machines had some of the characteristics of modern computers (such as program-controlled processing, capsule or digital computation), generic while machines that came after the ENIAC had even more of the features we typically associate with computers today (such as the ability to store a program as software in memory). Many of the features most popularly associated with today's computers, such as graphical user interfaces and real-time interactive operator input, were not developed until decades after ENIAC. However, the ENIAC was the first computer built to take full advantage of electronic processing speeds and to "think" for itself using conditional branching and nested subroutines. This made it the first machine capable of being programmed to solve a full array of computing problems. Additionally, all modern computers trace their lineage back to the ENIAC and the design for the ENIAC's successor machine, the EDVAC. For both of these reasons, the ENIAC deserves to be called "the first computer."

One early computer dictionary defines computer as a "device capable of accepting information, applying prescribed processes to the information, and supplying the results of these processes".[10] ANSI defines computer as "a data processor that can perform substantial computation, including numerous arithmetic operations, without intervention by a human operator during a run."[11]

These definitions differ to the extent that automaticity—freedom from the need for constant human input for operation—is stressed in the latter definition. But neither definition makes explicit that this automaticity must include automatic testing of intermediate processing results for certain conditions and automatic selection of how processing should proceed based on the results of those tests. Such a feature is what we call "conditional branching". Furthermore, neither definition requires the capacity to make multiple such decisions so as to create what we call "loops" and "nested subroutines". Without these features, a program-controlled computing machine is so limited in its usefulness that it can hardly be called a computer, because such a machine would not have the ability to "think" for itself, that is, to make decisions and act on those decisions in ways not strictly provided for by the programmer as a linear list of operations. The decision-making process is what distinguishes computers from calculators.

Until World War II, computing machines were "analog", estimating answers based on mechanical or electrical analogy, or if they were digital, they were either mechanical (using cogs, gears, pulleys, etc.) or electromechanical (using motors, relays, etc.), using moving parts that were slow and prone to failure. After the war—after the ENIAC—computers were built to be fully electronic and digital. The ENIAC changed everything. Once the power of electronic digital computing was realized, subsequent machines followed in the ENIAC's footsteps.

Even so, the history of computers is rich with clever and advances and technological dead-ends. Even though none of them led directly to the computers we have today, some of the following machines and concepts have claims to being "the first computer"—depending on the definition of computer.

Analytical Engine

British mathematician and inventor Charles Babbage worked on his design for a mechanical "Analytical Engine" from 1837-1871, but he never finished, and his machine was never built.  Most probably, Babbage's shortfall lay not any flaw in his design but the lack of political will to finance the machine's construction, which involved first tackling technological challenges in toolmaking.[12] The Analytical Engine was designed to be programmed using punched cards and it had separate places for processing and memory. It was a digital machine that facilitated conditional branching and nested subroutines, making it way ahead of of its time. Despite Babbage's cleverness, however, because his designs were never pursued to fruition, within 50 years they had been forgotten—becoming so obscure that 20th-century computer developers hadn't heard of Babbage when they began their work. The Analytical Engine thus never influenced the design of modern computers.

Zuse Z3 and Z4

German engineer Konrad Zuse in 1941 demonstrated his Z3 computer, a fully relay-based computing machine. A marvel both of logical design and wartime engineering, it was programmable, and used the binary floating-point numeral system common in computers today, but it could not conditionally branch.[13] The following year, Zuse began work on a successor machine, the Z4, but his work on the machine was interrupted by the Allied invasion of Germany in 1945 and not resumed until 1948; by that time, the explosion of electronic computer development in the U.S. and Great Britain had passed Zuse by. Because of wartime exigencies, lack of publication on his machines, and perhaps also because of the destruction of the Z3 in a 1943 bombing raid, Zuse's early work, though commendably impressive, never influenced the development of electronic computers.


British cryptologists and engineers in 1943 and 1944 completed their Colossus 1 and Colossus 2 computers. Like the ENIAC, these were electronic computers that used vaccum tubes, but they were special-purpose—their only task was to crack Axis codes. For reasons of British national security, the work on these machines was kept secret until the 1970s, and thus they, too, had no influence on the development of the modern electronic digital computer.

What about the Atanasoff-Berry Computer (ABC)?

Iowa State College math and physics professor John V. Atanasoff and electrical engineering graduate student Clifford Berry designed a computing machine in the late 1930s and early 1940s. It was noteworthy for using vacuum tubes in its calculation logic, which made the device partially electronic.  Yet it required extensive human intervention; rather than running from a program, a human operator had to guide the machine's progress after every significant step. This lack of automation and programmability means the ABC was a form of calculator and not a computer.  Despite this, a judge in 1973 ruled that the ABC was a computer in his decision to invalidate Mauchly and Eckert's ENIAC patent.

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  1. [10] Sippl, Computer Dictionary and Handbook, p. 67 (Bobbs-Merrill 1966).
  2. [11] American National Standards Institute (ANSI), American National Dictionary for Information Processing (X-3/TR-1-77).
  3. [12] "Mathematical Machines and Myths Concerning Their Makers or Babbage vs.
    , NBS Colloquium talk given by John Mauchly, Ambler, Pennsylvania, February 23, 1973.
  4. [13] The Z3 had two predecessors: the Z1 was not programmable, and the Z2 was essentially an interim prototype for the Z3.

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