Kathleen (Kay) McNulty was born in Creeslough, Co. Donegal on 12th February 1921. With the Irish War of Independence at its height, her father, James, an IRA training Officer was arrested and imprisoned on the night of her birth and served two years in Derry Gaol. On his release in October 1924, the family immigrated to America, settling in Pennsylvania. Here Kathleen attended junior school in Chestnut Hill and Hallahan Catholic Girls High School in Philadelphia.
Following graduation, she enrolled as a Maths Major at Chestnut Hill College for Women, graduating in 1942. Throughout her degree she joined every maths class that the college were offering including spherical trigonometry, differential calculus, projective geometry, partial differential equations, and statistics. With World War Two at its peak, within weeks of graduation she had secured a post with the U.S. Civil Service at the Moore School of Electrical Engineering, University of Pennsylvania. Her job involved computing ballistics trajectories used for artillery firing tables, central to the American war effort and Kay became prominent in her role.
After a few months, she moved to work on the differential analyzer in the basement of the Moore School, the largest and most sophisticated analog mechanical calculator of the time. Kay was quickly promoted to working on, and then supervising, calculations on the Differential Analyzer. With the invention of ENIAC (Electronic Numerical Integrator And Computer), these computations went from taking 40 hours (by hand), to an hour (by Analyzer), to just mere seconds (by ENIAC). Kay was recruited into the initial programming team. With no prior training and only schematics to work with, an all-woman team programmed the ENIAC.
Kay was transferred to Aberdeen Proving Ground's Ballistics Research Laboratory along with the ENIAC when it was moved there in mid-1947. In 1948 she married ENIAC co-inventor John Mauchly and together they had five children. After WWII, she assisted some of the world’s leading mathematicians on using the ENIAC, and helped instruct the next generation of computer programmers. She later also worked on the software design for newer computers including the BINAC and UNIVAC I, whose hardware was designed by her husband.
Following Mauchly's death in 1980, Kay carried on the legacy of the ENIAC pioneers by authoring articles, lecturing on software engineering and making herself available for interviews with reporters and researchers. In later years she married photographer Severo Antonelli whom she was married to for almost ten years.
In 1997 Kay was inducted into the Women In Technology International (WITI) Hall of Fame. Antonelli was diagnosed with inoperable cancer in early 2006, and died in April at the age of 85. Her contribution to the development of software computing and programmer is however infinite and will continue to live on through the technological developments of the 21st century.