Kathleen Rita McNulty Mauchly Antonelli

Quick Info

12 February 1921
Creeslough, County Donegal, Ireland
20 April 2006
Wyndmoor, Pennsylvania, USA

Kathleen McNulty Antonelli was an Irish-born American computer programmer who was one of the first to work with the early ENIAC machine.


Kathleen McNulty was born in Ireland but emigrated to the United States as a young child. We should explain the names under which we have listed her in this archive. She married John Mauchly in 1948 becoming Kay Mauchly then, some years after John Mauchly's death in 1980, she married Severo Antonelli. Her education was in Catholic Schools in the United States before entering Chestnut Hill College for Women in Philadelphia. At Chestnut Hill College she studied mathematics and it was in that subject that she graduated in 1942.

Of course 1942 was in the middle of World War II and by this time the war was strongly affecting the direction of academic research. The United States was specifically directing its research schools and staff towards the war effort. The University of Pennsylvania's Moore School of Engineering began putting on training courses for electronics and other disciplines as part of this war effort. They also began early research in the use of computers.

The Ballistic Research Laboratory had been set up at Aberdeen, in Harford county, northeastern Maryland as part of the Aberdeen Proving Ground, a military weapons testing site which had been established in 1917 during World War I. The Ballistic Research Laboratory consisted of staff from the Moore School and staff from the Aberdeen Proving Ground using their expertise on joint projects.

After graduating Kay McNulty was employed as a mathematician by the Moore School of Engineering where she worked on preparing firing tables for guns. McNulty described the work which she did in the following way:-
We did have desk calculators at that time, mechanical and driven with electric motors, that could do simple arithmetic. You'd do a multiplication and when the answer appeared, you had to write it down to reenter it into the machine to do the next calculation. We were preparing a firing table for each gun, with maybe 1,800 simple trajectories. To hand-compute just one of these trajectories took 30 or 40 hours of sitting at a desk with paper and a calculator. As you can imagine, they were soon running out of young women to do the calculations. Actually, my title working for the ballistics project was "computer". The idea was that I not only did arithmetic but also made the decision on what to do next. ENIAC made me, one of the first "computers", obsolete.
The ENIAC computer (Electronic Numerical Integrator and Computer) which McNulty refers to in the above quote was being constructed by John Mauchly and John Eckert in the Moore School of Engineering during the war years. It was designed for the specific task of compiling tables for the trajectories of bombs and shells to take over the calculations which McNulty and about 75 other women were carrying out. However the war had ended before the machine came into service but it was still used for the numerical solution of differential equations as intended. McNulty was one of six women who became operators of ENIAC making very substantial contributions to computer science, although it took many years before they received the credit which they deserve for their pioneering work.

Petzinger, in [3], describes the way that McNulty used ENIAC to solve differential equations after the construction of the machine was complete in February 1946:-
The first task was breaking down complex differential equations into the smallest possible steps. Each of these had to be routed to the proper bank of electronics and performed in sequence - not simply a linear progression but a parallel one, for the ENIAC, amazingly, could conduct many operations simultaneously. Every datum and instruction had to reach the correct location in time for the opeation that depended on it, to within 15000\large\frac{1}{5000}\normalsizeth of a second.
In 1948 McNulty married John Mauchly, one of the two designers of the ENIAC computer. By this time John Mauchly had left the Moore School and was designing further computers in partenership with John Eckert. John and Kay Mauchly lived on a farm in Amber Pennsylvannia and Kay continued to work with with her husband on the design of computer programs for the later BINAC and UNIVAC computers. She contributed skills in software design to these projects which complemented her husbands expertise in hardware design.

Some years after the death of her husband in 1980, Kay married Severo Antonelli and lived in Pennsylvania. Kay Antonelli was a keynote speaker at the Women In Technology International's East Coast Summit in Boston in 1998.

Antonelli died of cancer at Keystone Hospice in Wyndmoor.

References (show)

  1. D Ritchie, The Computer Pioneers : The making of the modern computer (New York, 1986).
  2. J Shurkin, Engines of the Mind : A History of the Computer (New York, 1984).
  3. T Petzinger, History of software begins with the work of some brainy women, Wall Street Journal (November 1996).

Additional Resources (show)

Written by J J O'Connor and E F Robertson
Last Update September 2009