The Moore School was by this time heavily involved with research specifically directed towards the war effort. Eckert taught a defence course at the Moore School and one of his students on the course was John Mauchly. It might seem strange that Mauchly, who was twelve years older than Eckert, should be his student. Mauchly was already an established academic teaching physics but he became involved in defence training as part of his contribution to the war effort. Eckert quickly became interested in Mauchly's ideas for the development of computers and for a while the two discussed these ideas frequently. Soon, however, Eckert moved on to undertake other military work at the School. Ashurst  relates how Eckert was:-
.... eventually involved with work on ultraviolet light and the development of the means to measure metal fatigue. Later, he went on to develop a method for measuring small magnetic fields to be used in detecting marine mines. He then went on to work on the electronics of radar and target locating and following equipment; these devices played a decisive part in weaponry, and their development and construction was considered to be of the very highest priority.After Mauchly's report on the construction of a computer was accepted, Eckert collaborated with him in the construction of the Electronic Integrator and Computer (ENIAC). At this time, May 1943, Eckert had almost completed the work for his masters degree and he was appointed as chief engineer on the project with the specific task of designing the electronic circuits. One of the major problems which had to be solved was how a machine with 18000 valves could function when the valves were relatively unreliable. This was one of the many problems which Eckert had to solve and he eventually achieved a lifetime of 2500 hours for each individual valve which made the operation of the computer viable.
The ENIAC computer was intended to be a general purpose one, but it was also designed for a very specific task, namely compiling tables for the trajectories of bombs and shells. ENIAC is described in :-
Completed by February 1946, the ENIAC was the first general-purpose electronic digital computer. It contained roughly 18000 vacuum tubes and measured about 2.5 metres in height and 24 metres in length. The machine was more than 1000 times faster than its electromechanical predecessors and could execute up to 5000 additions per second. Its operation was controlled by a program that was set up externally by wires on plugboards. The ENIAC was the most complex and influential electronic computer of its time ...Electronic computers are today machines based on binary arithmetic but this was not so for the ENIAC computer. Eckert designed electronic calculators which worked to base 10 for the ENIAC, reducing the number of components over a binary machine, but of course at the price of greater complexity.
Of course by 1946 when the ENIAC was completed World War II was over but the computer was used intensively, particularly on top secret problems associated with the development of nuclear weapons. Von Neumann was working on this project and became involved with the ENIAC computer and used it to solve systems of partial differential equations which were crucial in the work on atomic weapons at Los Almos.
Eckert left the Moore School at the University of Pennsylvania in October 1946, as did Mauchly. They started up the Electronic Control Company which they received an order from Northrop Aircraft Company to build the Binary Automatic Computer (BINAC). One of the major advances of this machine, which was used from August 1950, was that data was stored on magnetic tape rather than on punched cards.
The Electronic Control Company become the Eckert-Mauchly Computer Corporation and it received an order from the National Bureau of Standards to build the Universal Automatic Computer (UNIVAC). This was the first computer to be produced commercially in the United States with 46 UNIVACs being built. One of the major advances which the UNIVAC introduced was an ability to handle both numerical and alphabetical information with equal success.
Eckert and Mauchly were better at computer design than they were at the economics of running a company. The problem really lay in the fact that this was such a new area that costs of production were extremely hard to estimate. As a consequence the Eckert-Mauchly Computer Corporation soon hit financial difficulties.
In 1950 the Remington Rand Corporation acquired the Eckert-Mauchly Computer Corporation and changed its name to the Univac Division of Remington Rand. Eckert remained with Remington Rand and became an executive of the corporation. He continued with the company as it merged with the Burroughs Corporation to become Unisys. In 1989 Eckert retired from Unisys but continued to act as a consultant for the company.
Between 1948 and 1966 Eckert took out patents on 85 inventions, almost all electronic in nature. He received many awards for his pioneering work on computers. In 1966 he received the Harry M Goode Memorial Award, a medal and $2,000 awarded by the Computer Society:-
For his pioneering contributions to automatic computing by participating in the design and construction of the ENIAC, the world's first all-electronic computer, and of the BINAC and the UNIVAC, and for his continuing work in the design of electronic computing systems.Eckert received many awards for his pioneering work on computers. He was elected to the National Academy of Engineering in 1967 but perhaps the most prestigious honour was being awarded the US National Medal of Science in 1969. Both Eckert and Mauchly received the IEEE Computer Society Pioneer Award in 1980.
Eckert died from complications relating to leukaemia.
Article by: J J O'Connor and E F Robertson