Elaine Denniston: The woman who corrected Apollo’s code

Although her job description ended with punching programs into cards to be run by the computer, this sharp-eyed keypuncher corrected programmers' code on her own to ensure it ran properly.
By | Published: June 21, 2019 | Last updated on May 18, 2023
Elaine Denniston
Image courtesy of Draper
Away from the flurry of control rooms and high-end software engineering, there were many women working on computer programming for Apollo. In these early days of computer science, it took a village to create a single program, and few people worked on a given program alone from start to finish.

Instead, engineers wrote the programs on long sheets of paper, and someone else – a nontechnical staff member, usually – punched those programs into cards that the early computers could read.

Elaine Denniston was one of these keypunchers. Born and raised in Boston, Massachusetts, she was hired into MIT’s Instrumentation Lab (now called Draper) via a staffing agency on the basis of her experience keypunching cards for an insurance company. She had only a high school education. In her mind, it was simply a job, and she was a young mother with children to feed. “Apollo was in the background,” she recalls. “I was a fairly naive, immature 26- or 27-year old. … I didn’t have a science background. I didn’t even take physics because [my high school] was a girls’ school.”
But half a century later, her former boss would remember Denniston with the rest of the section’s Apollo team.

Staying tough

Denniston’s job was simple on the face of it. Each engineer on the team wrote their own piece of the code, which Denniston collected from them. She then keypunched the program into batches of cards six inches thick, containing hundreds or thousands of pages. These cards had to be run together through the computer, usually overnight, and a single mistake could ruin the whole run, wasting valuable time while the space race was still very much on.

The logistics of collecting all the code from a roomful of engineers well aware they were making – or trying to make – history was more demanding. Her boss at the time, Dan Lickly, recalled for Draper, “And of course these prima donna programmers would be late, ‘I got to do this over,’ ‘Give me another half hour,’ and so on and so on. [Denniston] had to go around at night before she left and beat up on all these programmers to get their information, run it, make sure there were no errors in it, and then turn it in for the overnight run.”
Denniston is only slightly more circumspect: “I don’t want to say nag, but that’s kind of what I did. … I had two young children, and I had to get home to them,” she told Astronomy.
Computers of the Apollo era used punch cards to read programs. If the card (or the program) contained an error, valuable computing time was lost.
Image courtesy of Draper

Sharp eyes

But her nagging isn’t what cemented her in her supervisor’s memory. Denniston also reviewed the engineers’ code, though she didn’t think of it like that at the time. “I would read over what people had written and punch them and would notice if something hadn’t been completed. I had absolutely no programming experience, but I thought if you had a left parentheses, you should have a right parentheses somewhere,” Denniston says.

She was right. These days, most programmers rely on text editors that use font color to hint when developers have dropped a parentheses or a typed a period instead of a comma, similar to the way a word processor will underline a misspelled word. But in those days, there were only the tired eyes of the programmer himself or the overnight run crashing to indicate a mistake – unless Elaine Denniston caught it first.
Although Denniston started as a temp, she was soon hired on directly by the Instrumentation Lab. But she stayed only two years. “I trained somebody to do what I did, and when they reorganized my department, they made them my boss,” she says. “He had some college, a few credits. I had none at the time.” She acknowledges that the difference in their education was perhaps valid, but at the time, the reason she was given for being overlooked was that “they needed someone to come in if the program failed, no matter what time,” she says. She feels that her position as a mother was what truly closed that door to her. Either way, it was clear to her that she would not be advancing further. “I think looking back that was the only time I felt being a woman was against me, so to speak,” she says.

“But in the end, that turned out to be the best thing that could have happened to me,” she says now, because she left with an “I’ll show them” attitude. She decided to go to college. Her husband, a doctor, recommended what he referred to as “that school over in Wellesley.” “He meant Harvard,” Denniston laughs, and laughs again when she recalls being interviewed by the school. “They asked me why do I want to come to Harvard? ‘I’ll get a good education,’ I told them. ‘And it’s the closest to where I live.’” Denniston says the interviewer was taken aback at her response. But within days, she had been accepted.

Denniston in 1977 at her graduation from law school.
Image courtesy of Draper

Moving on

After Harvard, she went on to law school and spent most of her career in the public sector, working for the city of Boston or the district attorney’s office. She has been retired since 2012.

But without the space race, the magic of keypunching evaporated for her. “When I was in college, a couple of times I took up a keypunching job. Boy was it boring,” she says.
“I didn’t realize then that what I did was anything special,” Denniston admits. “I typed, I found errors, I nagged people.” But she credits her start with Apollo for her interest in science, even if she never pursued it professionally. She reads Dava Sobel’s books about science and scientists, and has visited the Greenwich Observatory with her son, where she was fascinated by the progression of clock technology.

She looks back on her time with Apollo fondly. “I think it had to do with doing things that were interesting, and doing them well,” she says.