The "Original file" consists primarily of the records of the Eckert-Mauchly Computer Corporation and documents the efforts of Eckert and Mauchly to develop and market the ENIAC, BINAC, and UNIVAC computers. The records on ENIAC trace the development of the first electronic digital computer from its conception in 1942 through its completion in 1945. Included are a copy of Mauchly's original proposal to the Ordnance Department, a copy of Mauchly's original proposal to the Ordnance Department, his correspondence with John V. Atanasoff, and his lecture notes from the University of Pennsylvania's Moore School of Engineering. There is a complete set of ENIAC progress reports, as well as correspondence between Herman Goldstine, the Army's chief liaison and the engineers who worked on the project. There are also files on the EDVAC computer, the first with stored memory capacity, which was developed by John von Neumann.

The records of the Eckert-Mauchly Computer Corporation proper describe the development of UNIVAC on a component-by-component basis. They include technical memoranda, progress reports, engineering notebooks, and patent files. Customer correspondence includes letters and contracts with the National Bureau of Standards, A.C. Neilsen, Northrop Aviation, Fairchild-NEPA, and the American Totalisator Company.