In the late 1930s, John Atanasoff was still trying to develop ways to facilitate the process of calculating solutions to the extended systems of linear algebraic equations that were applicable to his research work. He became convinced that the digital approach offered considerable advantages over the slower and less accurate analog machines. In December of 1939, working with his graduate student Clifford Berry, John Atanasoff developed and built the prototype of the first electronic digital computer, which would be fully completed in 1942. This prototype of the first computer included four significant and entirely novel operating principles in its operation: The binary system, regenerative data storage, logic circuits as elements of a program, and electronic elements as data carrying media.

"After the prototype had started working, we were convinced we could build a computer capable of calculating whatever we would like to", wrote Atanasoff. Having demonstrated the viability of the four major principles, the prototype unequivocally opened the way for all present day computers.

In their history of the ENIAC computer, Alice R. Burks and Arthur W. Burks summarize the Atanasoff achievement as follows: "He invented a new type of a serial storage module, applicable to digital electronic computing. He formulated, developed and proved the major principles involved in electronic circuits for digital computing, principles that included arithmetical operations, control, transition from one to another number base systems, transfer and storage of data, and synchronized clocking of the operations. Having applied that data storage and those principles, he constructed a well-balanced electronic computer with centralized architecture, including storage, and arithmetically controlled input/output devices. He had invented the first-ever specialized electronic computer with such a degree of multi-aspect applicability."

The ABC computer would have been fully operative by 1943, had the efforts of John Atanasoff and Clifford Berry not been interrupted by World War II. In September of 1942, Atanasoff was conscripted into the military and was forced to set aside his work on the computer. He began working at the Naval Ordnance Laboratory (NOL), a research laboratory at the Armed Forces Ordnance Administration, where, as a theoretical physicist, he was put in charge of testing acoustic mines, depth charges, and other similar projects. From 1942 to 1966, Atanasoff\'s scientific research centered on the dynamic principles of naval ships. During this time, he patented more than 30 devices, including the first mine-sweeping unit for blowing up hydrodynamic naval mines; instruments for detection and recording of high amplitude seismic and sonic waves; a unit computing and recording projectile trajectory errors in artillery shelling; postal sorting systems; automated systems for parcel post handling; quick search systems for classified information items; and an electronic quartz clock. Simultaneously, he worked on several developments related to national defense and naval armament systems, including work on guided missiles.

In 1945 John Atanasoff dedicated the results of his innovative professional work to a number of governmental and industrial projects. He also established two successful companies and served each simultaneously as chief executive.