Feeling a little geeky?  Nostalgic for the days when NASA had less computing power than your cell phone?  In honor of Women's History Month, the Libraries and the National Museum of American History would like to enable you to build your own ENIAC.   Ok, well, maybe not really build – you might have trouble finding over 17,000 vacuum tubes – but you could learn how to run one!

First a little context…we were thrilled a few months back when Peggy Kidwell, curator of Mathematics at the National Museum of American History, decided to transfer a piece of printed computing history to our Dibner Library of the History of Science and Technology.  It was a complete set of the operational and technical manuals for the first 'general purpose' computer, ENIAC.

Left: Betty Jennings (Mrs. Bartik) Right: Frances Bilas (Mrs. Spence) operating the ENIAC's main control panel while the machine was still located at the Moore School. U.S. Army Photo from the archives of the ARL Technical Library. [Image from Wikimedia Commons ]

ENIAC, short for Electronic Numerical Integrator And Computer, was built at the Moore School of Engineering, University of Pennsylvania for the U.S. Army Ballistics Research Laboratory and completed in 1946 after the end of World War II. ENIAC was designed by J. Prespert Eckert and John Mauchley, created by many talented engineers and mathematicians at the Moore School, and programmed, debugged and operated by 6 women - Kathleen McNulty Mauchly Antonelli, Frances Snyder Holberton, Marlyn Wescoff Meltzer, Frances Bilas Spence, Ruth Lichterman Teitelbaum, and Jean Jennings Bartik.

ENIAC grew out of a need to more quickly and efficiently perform the computations to create ballistics trajectory and firing tables. As the majority of men on college campuses had been drafted for the war, the computations required for creating those tables were primarily done by women (many of whom were themselves mathematicians or math majors) operating simple mechanical calculators.  As ENIAC was being developed, some of the same women who had been employed as 'computers' for the Army were then hired as 'operators' for the new electronic computer.  Their jobs turned out to be much more than just 'operating' the computer.  For starters, when the original programmers were hired in 1946, because the computer itself was not yet finished and no manuals had been written they had to learn how ENIAC worked by studying circuit diagrams.

Programming ENIAC was a complicated and time consuming process that involved figuring out the logical sequence of operations that would correctly perform the calculations; manually moving and plugging in cables; physically flipping switches; creating the input and interpreting the output (both on punch cards); and troubleshooting the 40 parallel units that made up ENIAC with 18,000 vacuum tubes,1,500 relays, 70,000 resistors, and 10,000 capacitors.  Programming to do one calculation often took days and could take longer if say, cleaning staff accidentally knocked out a cable and plugged it back in to the wrong plug! Eventually, in 1948 a simple read-only storage mechanism was devised that greatly reduced the time it took to program ENIAC.  This new stored-program process was developed by a team of programmers and engineers, including four programmers lead by Jean Bartik, Richard Clippinger,John von Neumann, Adele Goldstine, John Giese, and A. Galbraith.   All 6 of the original ENIAC programmers were inducted into the Women In Technology International Hall of Fame in 1997. 

Adele Goldstine, one of the original 6 programmers, also wrote the technical manual and the Report on the Eniac, copies of which are now at the Dibner Library of Science and Technology. The Libraries is happy to report that we are now digitizing all the operational and technical manuals, including diagrams, and will be making them available online at the Internet Archive. We have finished  Report vol. 5, and hope to have some of the operational manuals available in the coming month. The operations manuals consist of large circuit diagrams, folded into a book-format, and are taking a little longer to scan than the average book! 

Other resources:

There are many books, websites, and histories of computing which have more on ENIAC – here are just a few.   If you would like to see pieces of the original ENIAC, there are many in institutions across the country including at the School of Engineering and Applied Science at the University of Pennsylvania, National Museum of American History, and the Computer History Museum in Mountain View, California.

I highly recommend this transcript of 50 Years of Army Computing From ENIAC to MSRC (pdf, opens in new window) edited by Thomas J. Bergin from a 1996 symposium. It has fascinating first-person accounts of what it was like to work on ENIAC.

University of Pennsylvania Library has an older, but quite informative history of John Mauchly and the development of ENIAC.

And of course, Landmarks in Digital Computing: A Smithsonian Pictorial History, by Peggy A. Kidwell and Paul E. Ceruzzi, Smithsonian Institution Press, 1994 is pretty good too…

—Keri Thompson