Tech WCW #4 – Jean Jennings Bartik


On February 14th 1946 the Electronic Numerical Integrator and Computer (ENIAC) was unveiled to the public.  It was the first general purpose electronic digital computer and it was Turing Complete.  The project was funded by the United States Military to speed up mathematical tasks, most notably artillery firing tables for the Army for World War II.

ENIAC could calculate the trajectory of a shell that took 30 seconds to reach its target, in 20 seconds.  Prior to ENIAC this computation would take a “Computer” (a person who did the mathematical calculation by hand) 1 to 2 days to complete.  Not only was ENIAC faster than a speeding bullet it was orders of magnitude faster than humans at the task.

While ENIAC was completed too late to be used in World War II it was a huge advance in the field of computing, and proclaimed a huge success.  The two engineers, John Mauchly and J. Presper Eckert, who designed the computer were widely celebrated along with the rest of the hardware engineering team.  However the six original Programmers of the ENIAC were widely unknown until Kathy Kleiman started the ENIAC Programmers Project in the 1980s to share the story of Frances “Betty” Snyder Holberton, Kathleen McNulty Mauchly Antonelli, Marlyn Wescoff Meltzer, Ruth Lichterman Teitelbaum, Frances Bilas Spence, and Jean Jennings Bartik.

Jean Jennings Bartik was born on December 27th 1924 on a farm in Gentry County, Missouri.  She read voraciously as a child and longed to leave Missouri.  She saw marriage as an impediment to her desire for adventure claiming, “Why would I want to get married I haven’t been anywhere I haven’t done anything”

At the age of 16 she began college at Northwest Missouri State Teachers college majoring in math and a minor in english.  While Bartik came from a long line of teachers, she did not want to become a teacher herself, so her professor brought her job advertisements, one for a “systems service girl” at IBM and one for a “computer” at Aberdeen Proving Grounds.

Bartik was offered the job of a computer at Aberdeen and jumped on the next train at the beginning of 1946.  Along with dozens of other women she began performing artillery firing tables by hand.  In June of 1946 Bartik applied for a position as a programmer for the newly formed ENIAC project.  She was chosen along with five other women.

Bartik along with the other ENIAC Programmers went through a two month training in Aberdeen to learn how to wire up the boards for the punch-card machines, before returning to The University of Pennsylvania in August 1946.  Once there they were given the Operational Manual for the ENIAC.  Bartik and Holberton holed up in a classroom and began the arduous task of understanding how the machine worked without any access to the machine itself.

[Diagrams from the ENIAC Operating Manual]

In September of 1946 all the ENIAC Programmers reconvened in one room and the project began in ernest.  The acceptance test for the project was calculating trajectories.  While all the programmers had done this by hand, translating this task to run on the ENIAC was not simple.  The ENIAC had twenty accumulators which could each be programmed separately and then a master programmer terminal which would coordinate the sub-programs.  While the ENIAC could be programmed to perform complex operations like loops and branches, none of these existed as stored programs, the Programmers had to create these from scratch for every program by wiring up the machine correctly and setting the right switches.

Programming the ENIAC was an arduous task, designing the program on paper often took weeks, and then setting the machine to run it could take a day or more, followed by another day or so spent verifying and debugging the program, which often required crawling into the machine.  Do to the lengthy set up time programs were only changed after numerous calculations had been performed.

After the war Dr. Richard Clippinger and John von Neumann began work on stored program computers, a computer that stores program instructions in electronic memory.  Clippinger recruited Bartik to set up a group of four or five programmers at The University of Pennsylvannia under his direction, who would program the ENIAC and help him turn it into a stored program computer.  Von Neumann and Clipplinger would work on the instruction set at Princeton and consult with Bartik and her group ever couple of weeks.  Bartik advocated for shrinking the instruction set to make it simpler at first to get it working on the ENIAC.  While they were working on the theory she helped keep them grounded in the reality of the hardware the instructions had to run on.  By 1948 the ENIAC was successfully transformed into a stored program computer which could run programs sequentially.

Meanwhile Eckert and Mauchly had left the University of Pennsylvannia to form their own company the Eckert-Mauchly Computer Corporation (EMCC).  They recruited Bartik to program their new computers the BINAC and the UNIVAC.

Bartik and Spence programming the ENIAC

The BINAC, the Binary Automatic Computer, was the worlds first stored program computer.  Unlike the ENIAC it used binary  instead of the decimal system.  It also used magnetic tape to store data and programs instead of punch cards.  Bartik programmed a guidance system to run on it for Northrop Aircraft.

The UNIVAC, the Universal Automatic Computer, was designed for business and administrative use.  The United States Census Bureau purchased one as well as CBS which used it to predict the results of the 1952 presidential election in the United States.  Bartik was responsible for the design of the UNIVAC’s logical circuits.

In 1951 Bartik left the computer industry to raise her three children.  In 1967 she re-entered the field working for a series of companies, Auerbach Corporation, Interdata, Systems Engineering Lab in Florida, Honeywell, and Data Decisions.  When Data Decisions closed in 1986 Bartik was unable to find another job in the industry do to gender and age discrimination.

Bartik died on March 23rd 2011 in Poughkeepsie, New York, USA

In 2009 Bartik received a Pioneer Award from the IEEE Computer Society.  In 2008 she was named a fellow by the Computer History Museum in Mountain View California.  Her alma-mater Northwest Missouri State named the Jean Jennings Bartik Computing Museum after her.

Her autobiography Jean Jennings Bartik and the computer that changed the world was published in 2013.


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