Recruited As "Computers"

Kleiman learned from the women that they were among the more than 80 female college graduates in Math who had been recruited by the US Army as "computers", that is to perform the ballistic calculations required to create the firing tables needed for artillery and other weaponry. These young women meticulously performed complex mathematical equations by hand using mechanical desk calculators  and extremely large sheets of columned paper.  When the ENIAC was developed, six of these skilled female human computers – Kathleen McNulty, Jean Jennings, Betty Snyder, Marlyn Wescoff, Frances Bilas, and Ruth Lichterman – were selected to become its first programmers.

Because the ENIAC project was classified, the programmers were denied access to the machine until they received their security clearances.The logical diagrams were all they had to help them figure out how to make the ENIAC work. Lacking any programming tools whatsoever, the programmers had to physically program the ballistics program by using the switches,  cables and digit trays to physically route the data and program pulses through the machine, re-configuring it for every new program. As they told Kleiman, on the basis of the wiring diagrams and logical diagrams of ENIAC, they were told to figure out how its 42 panels worked. Then they had to break their program down into steps the machine could handle. This involved not only placing pieces of wire in the appropriate panel but also figure out the timing and each panel’s calculation timing was different.

No one showed them how to do a flow chart - flow chart technology didn’t even exist, so they created their own and called them pedalling sheets. They used these to keep track of each step of the program as well as where all the switches, cables and wire went.

Revealing A Forgotten History

When the time came for ENIAC's 50th Anniversary Kleiman discovered that the woman programmers hadn't even been invited (a state of affairs that was quickly changed, as the photo  below shows) which spurred her into seeking recognition for their accomplishments. She did this by recording 20 hours of broadcast-quality oral histories from Kathleen McNulty Mauchly, Jean Jennings Bartik, Marlyn Wescoff Meltzer, and lifelong programming pioneer Betty Snyder Holberton.

Kathy Kleiman with Jean Jennings Bartik, Marlyn Wescoff Meltzer, Kathleen McNulty Mauchly Antonelli and Betty Snyder Holberton (seated)

Later Kleiman went on to produce a documentary combining the women sharing their own story with Movietone footage from the 1940s, to tell their dramatic story. The Computers premiered at the Seattle International Film Festival (2014) and won best documentary short at the United Nations Association Film Festival (UNAFF 2016). The film is still available via the Kleiman's ENIAC Project website and it has recently been converted into a book, Proving Ground, whose trailer uses a few minutes of the same footage.

In this TED Talk from 2018 Kleiman gives her account of identifying the ENIAC woman and how they have served as role models for her and for today's generation of women programmers.