Kay McNulty married physicist and ENIAC co-designer John W. Mauchly in 1948, beginning a lifelong personal and professional partnership.
In 1948, Kay McNulty married John W. Mauchly, the physicist and co-designer of the ENIAC computer alongside J. Presper Eckert. The exact month and day of the marriage are not precisely documented in surviving records, though the union is consistently dated to 1948 across historical sources.
The marriage united two key figures from the ENIAC project: Kay, one of its pioneering programmers, and John, one of its principal engineering minds. Their relationship had developed during their collaborative work on the ENIAC project at the Moore School, where Kay's deep technical understanding of the machine's operation made her an invaluable colleague and eventually a spouse who shared in his ongoing computing ventures.
Following their marriage, Kay continued to be intimately involved in her husband's subsequent computing projects, including the BINAC and UNIVAC I systems, contributing her programming expertise even as she raised their five children together. Their partnership exemplified a rare case in this era of a professional woman continuing technical work in tandem with her husband's ventures, and Kay is often credited with quietly shaping his engineering enterprises with her direct expertise from the ENIAC era. John Mauchly passed away in 1980, after which Kay later remarried photographer Severo Antonelli, adopting the surname by which she is frequently cited in modern historical literature.