Jean Bartik: The ENIAC Programmer Who Wrote Code Without a Manual

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Betty Jean Jennings was born in Gentry County, Missouri, in 1924, the sixth of seven children of a farmer and schoolteacher. By 14 she was driving herself to high school in a neighboring town, and at 16 she graduated as salutatorian. In college she switched from journalism to mathematics after clashing with her advisor, and in 1945 she was the only student in her class to earn a math degree. The Army hired her as a human computer, calculating artillery trajectories by hand, and she soon applied to work on a secret machine called ENIAC.

This episode tells how she and five other women became its first programmers. Without security clearances, they were not allowed to see the computer, so they worked in empty classrooms and fraternity houses from circuit diagrams and interviews with the engineers. With co-lead Betty Holberton, she developed subroutines and nesting, then set the machine up by routing cables and flipping switches by hand. The story follows her from that triumph to decades of obscurity and a late, deserved recognition.

• At the public demonstration in February 1946, ENIAC computed a trajectory in 20 seconds that would have taken a human computer 40 hours. The praise went to hardware builders John Mauchly and J. Presper Eckert.
• In 1948 Bartik led the team that converted ENIAC into a stored program computer. Much of the 60 order code survives in her handwriting.
• She worked on BINAC, the first computer to use magnetic tape, designed logic circuits for UNIVAC I, and co-wrote the Sort/Merge generator with Holberton.
• After Remington Rand bought the company, a rule against married couples working together forced her to resign. She later earned a master's in English and spent 25 years as a real estate agent.
• In 1986 researcher Kathy Kleiman was told the women in old ENIAC photographs were just models. Her search for them led to documentaries, a Computer History Museum fellowship, and a Drupal theme named Bartik.