Machines such as the Z3, the Atanasoff – Berry Computer, the Colossus computers, and the ENIAC were built by hand using circuits containing relays or valves ( vacuum tubes ), and often used punched cards or punched paper tape for input and as the main ( non-volatile ) storage medium.

The 1946 ENIAC computer used 17, 468 vacuum tubes and consumed 150kW of power.

ENIAC had twenty ten-digit signed accumulators 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.

ENIAC used four of the accumulators, controlled by a special Multiplier unit, to perform up to 385 multiplication 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.

ENIAC used common octal-base radio tubes of the day ; the decimal accumulators were made of 6SN7 flip-flops, while 6L7s, 6SJ7s, 6SA7s and 6AC7s were used in logic functions.

The ABC, ENIAC and Colossus all used thermionic valves ( vacuum tubes ).

The U. S. Army Ordnance Museum at Aberdeen Proving Ground, Maryland, where ENIAC was used, has one of the function tables.

His experience with programming the ENIAC and its successors led him to create Short Code ( see " The UNIVAC SHORT CODE "), the first programming language actually used on a computer ( predated by Zuse ’ s conceptual Plankalkul ).

The ABC used regenerative drum memory ; The ENIAC used electronic decade counters.

The ABC used its tubes to implement a binary serial adder while the ENIAC used tubes to implement a complete set of decimal operations.

The latter was used extensively in the computation of artillery firing tables prior to the invention of the ENIAC, which, in many ways, was modelled on the differential analyser.

Diode logic goes back as far as ENIAC and was used in many early vacuum tube computers.

ENIAC used this representation.

One of the first general purpose computers, ENIAC, was used as a very simple type of physics engine.

The ENIAC was used to create the first weather forecasts via computer in 1950 ; in 1954, Carl-Gustav Rossby's group at the Swedish Meteorological and Hydrological Institute used the same model to produce the first operational forecast ( i. e. routine predictions for practical use ).

The hydrodynamic calculations involved were daunting, and ENIAC was used to run a computer simulation of the Super in December 1945 and January 1946.

However, up to the 1940s, many subsequent designs ( including Charles Babbage's machines of the 1822 and even ENIAC of 1945 ) were based on the decimal system ; ENIAC's ring counters emulated the operation of the digit wheels of a mechanical adding machine.

It is quite conventional in principle in past and present computing machines of the most varied types, e. g. desk multipliers, standard IBM counters, more modern relay machines, the ENIAC " ( Goldstine and von Neumann, 1946 ; p. 98 in Bell and Newell 1971 ).

The first electronic programmable digital computer, the ENIAC, using thousands of octal-base radio vacuum tubes, could perform simple calculations involving 20 numbers of ten decimal digits which were held in the vacuum tube accumulators.

Decimal computers sold in that era, such as the IBM 650 and the IBM 7070, had a word length of ten digits, as did ENIAC, one of the earliest computers.

A dozen of these devices were built before their obsolescence was obvious ; the most powerful was constructed at the University of Pennsylvania's Moore School of Electrical Engineering, where the ENIAC was built.

Penn's educational innovations include: the nation's first medical school in 1765 ; the first university teaching hospital in 1874 ; the Wharton School, the world's first collegiate school of business, in 1881 ; the first American student union building, Houston Hall, in 1896 ; the country's second school of veterinary medicine ; and the home of ENIAC, the world's first electronic, large-scale, general-purpose digital computer in 1946.

Later work confirmed that tube unreliability was not as serious an issue as generally believed ; the 1946 ENIAC, with over 17, 000 tubes, had a tube failure ( which took 15 minutes to locate ) on average every two days.

Below title bar: events after World War II: From left to right: The Declaration of the State of Israel in 1948 ; The Nuremberg Trials were held after the war, in which the prominent members of the political, military, and economic leadership of the defeated Nazi Germany were prosecuted ; After the war, the United States carried out the Marshall Plan, which aimed at rebuilding Western Europe ; ENIAC, the world's first general-purpose electronic computer .| 420px | thumb

Eckert, a co-inventor of ENIAC, discusses its development at the University of Pennsylvania's Moore School of Electrical Engineering ; describes difficulties in securing patent rights for ENIAC and the problems posed by the circulation of John von Neumann's 1945 First Draft of the Report on EDVAC, which placed the ENIAC inventions in the public domain.

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, which placed the ENIAC inventions in the public domain.

Eckert and Mauchly and the other ENIAC designers were joined by John von Neumann in a consulting role ; von Neumann summarized and discussed logical design developments in the 1945 First Draft of a Report on the EDVAC.

The ABC was binary ; the ENIAC was decimal.

From 1945-1946, Lehmer served on the Computations Committee at Aberdeen Proving Grounds in Maryland, a group established as part of the Ballistics Research Laboratory to prepare the ENIAC for utilization following its completion at the University of Pennsylvania's Moore School of Electrical Engineering ; the other Computations Committee members were Haskell Curry, Leland Cunningham, and Franz Alt.

collection contains reports, including the original report on the ENIAC, UNIVAC, and many early in-house National Bureau of Standards ( NBS ) activity reports ; memoranda on and histories of SEAC, SWAC, and DYSEAC ; programming instructions for the UNIVAC, LARC, and MIDAC ; patent evaluations and disclosures relevant to computers ; system descriptions ; speeches and articles written by Margaret Fox's colleagues.

The Z3 and Colossus were developed independently of each other and of the ABC and ENIAC during World War II.

The 1946 ENIAC had more tubes than the SSEC and was faster in some operations, but was originally less flexible, needing to be rewired for each new problem.

Many computers of this time tried to avoid this problem by using only AC-coupled pulse logic, which made them very large and overly complex ( ENIAC: 18, 000 tubes for a 20 digit calculator ) or unreliable.

Detail of the back of a section of ENIAC, showing vacuum tubes

ENIAC vacuum tubes in holders

ENIAC contained 17, 468 vacuum tubes, 7, 200 crystal diodes, 1, 500 relays, 70, 000 resistors, 10, 000 capacitors and around 5 million hand-soldered joints.

Detail of the back of a section of ENIAC, showing vacuum tube s

( Such tests were run without cost, since the ENIAC would have been left powered on anyway in the interest of minimizing vacuum tube failures.

The ENIAC was huge, measuring 30 by 60 feet and weighing 30 tons with 18, 000 vacuum tubes.

* Mauchly, John, The ENIAC ( in Metropolis, Nicholas, J. Howlett, Gian-Carlo Rota, 1980, A History of Computing in the Twentieth Century, Academic Press, New York, ISBN 0-12-491650-3, pp. 541 – 550, " Original versions of these papers were presented at the International Research Conference on the History of Computing, held at the Los Alamos Scientific Laboratory, 10 – 15 June 1976.