At the dawn of the computer age, when the first room-sized electronic machines were being coaxed into life, the people who actually programmed them were almost all women — and one of the most important of them was born in a small village in County Donegal. Kathleen McNulty, known as Kay, was one of the six original programmers of the ENIAC, among the first general-purpose electronic computers ever built. At a time when programming was barely understood as a discipline, she helped invent it. Her story is a reminder that the digital world we live in has Irish roots, and that women were there at its very creation.
Quick answer: Kathleen "Kay" McNulty, born in Creeslough, County Donegal, in 1921, was one of the six original programmers of the ENIAC, one of the first general-purpose electronic computers, in the 1940s. Working before modern programming languages existed, she and her colleagues programmed the machine by physically configuring its circuits to solve complex calculations. McNulty was a genuine pioneer of computer programming, helping to establish the foundations of a discipline that did not yet formally exist.
Who was Kay McNulty?
Kathleen McNulty was born on February 12, 1921, in Creeslough, a village in County Donegal in the northwest of Ireland. Remarkably, she was born on the very night her father, a Republican, was arrested during the Irish War of Independence, and he spent two years in prison before the family emigrated to the United States in 1924, settling in Philadelphia. Young Kathleen spoke only Irish when she arrived in America, and had to learn English as a child — a striking detail for someone who would go on to help create the language of computers.
She proved a gifted student, especially in mathematics, and graduated from college in 1942 as one of only a small number of women to major in the subject. The timing was significant: the United States had just entered the Second World War, and the army was hiring mathematically talented women to perform the enormous volume of ballistics calculations the war effort required. McNulty was recruited as a human computer — one of the people, overwhelmingly women, who carried out complex calculations by hand and with mechanical calculators. It was demanding, skilled work, and it placed her at exactly the right point to help usher in the electronic age.
How did McNulty help create computer programming?
The calculations the human computers performed were so laborious that the army funded the construction of a machine to do them faster: the ENIAC, the Electronic Numerical Integrator and Computer, a vast machine of some eighteen thousand vacuum tubes that filled a large room. When it was completed in the mid-1940s, someone had to make it actually carry out calculations — and that task fell to a team of six women, including Kay McNulty, chosen for their mathematical skill. They became the ENIAC's first programmers.
It is hard to overstate how pioneering this work was. There were no programming languages, no manuals, no instructions — nothing of what we now think of as software existed. To program the ENIAC, McNulty and her colleagues had to understand the machine's circuits in detail and physically configure it for each problem, setting switches and connecting cables by hand to route the calculation through the machine. They were, in effect, inventing the practice of programming as they went, working out how to translate a mathematical problem into something a machine could execute. McNulty is credited with conceiving the idea of using subroutines — reusable sequences of instructions — to make the most of the machine's limited capacity, a concept fundamental to programming ever since.
Why were the ENIAC programmers overlooked?
Honesty requires acknowledging that for decades these women received almost no recognition. When the ENIAC was unveiled to the public and the press in 1946, the attention went to the male engineers who had designed and built the hardware, while the women who had programmed it were largely ignored — some were not even named, and in photographs they were sometimes assumed to be models posing beside the machine rather than the experts who made it work. The programming itself was, at the time, undervalued as mere clerical labour, when in truth it was a profound intellectual achievement.
It is only in recent decades that the contribution of McNulty and her five colleagues — Frances Bilas, Betty Jean Jennings, Ruth Lichterman, Kathleen McNulty, Frances Spence, and Marlyn Wescoff — has been properly recognised by historians of computing. Their work is now understood as foundational to the entire field of software, and they are increasingly honoured as the pioneers they were. The fair and honest account places these women at the origin of computer programming, and Kay McNulty among the most accomplished of them. Their belated recognition is a small act of historical justice.
What was Kay McNulty's legacy?
Kay McNulty continued to work in early computing, contributing to the development of later machines, and she married John Mauchly, one of the principal inventors of the ENIAC itself. She raised a large family while maintaining her interest in the field she had helped pioneer, and she lived to see the recognition of the ENIAC programmers finally begin in her later years, before her death in 2006. Her name is now firmly established in the history of computing.
For Ireland, McNulty is a wonderful figure to celebrate: a Donegal girl who arrived in America speaking only Irish and grew up to help invent the practice of computer programming. She brings to this series both a woman's pioneering achievement and a reminder that the digital age, which now shapes every life on earth, had a hand in it from County Donegal. Kay McNulty holds a proud and important place in the story of Irish inventors and scientists who changed the world.
To celebrate your own Irish heritage, search your surname in the search bar at Celtic Ancestry Gifts. You will find a woven family-name blanket to pass down through the family, a crest mug for everyday pride, and a family-name garden flag to fly your colours, each made for your name and shipped free worldwide. Stewart from Glasgow and Anna from Indiana built this store to help Irish families everywhere celebrate their heritage.
