Today in History -August 7, 1944 - Largest electromechanical calculator ever built. The IBM Automatic Sequence Controlled Calculator (ASCC) (also called the Harvard Mark I) was the largest electromechanical calculator ever built and the first automatic digital calculator in the United States. Its size was 51 feet wide and eight feet high and weighted nearly five tons. Inspired by Babbage’s vision of the analytical engine, it also added important new features. The upper left photo shows the assembly of the ASCC at Harvard in February 1944 with workers wearing the suits and ties typical of IBM even today.

IBM reports that it linked 78 adding machines and calculators together, using 765,000 parts, 3,300 relays, over 500 miles of wire and more than 175,000 connections. Using the calculators in synchronous parallel, it could perform table lookup and the four fundamental arithmetic operations, in any specified sequence, on numbers up to 23 decimal digits in length. It used punched cards, paper tape and manually set switches as input. For internal and intermediate results it had 60 switch registers for constants, 72 storage counters, a central multiplying-dividing unit, functional counters for computing transcendental functions, and three interpolators for reading functions punched into perforated tape. Electric typewriters or punched cards were used for output.

Howard H. Aiken, a graduate student in theoretical physics at Harvard University in the 1930’s originally proposed a large-scale digital calculator to the faculty of Harvard’s physics department. As funding was a major issue, he later took his idea to the Monroe Calculating Machine Company and then to IBM where James Bryce championed the idea and obtained funding from IBM President Thomas J. Watson in 1939 at IBM’s North Street Laboratory in Endicott, N.Y. Although progress was slowed by wartime demands, the calculator parts were eventually shipped to Harvard in February 1944 and assembled on site. It was completed and presented on August 7, costing IBM approximately $200,000 on the project. IBM donated an additional $100,000 to Harvard to cover its operating expenses. It was used for 15 years, originally for use by the Navy during the war to run repetitive calculations for the production of mathematical tables. Many of its electromechanical counters and parts are now on exhibition at the Smithsonian Institution in Washington, D.C.

It was only a few years later on February 14, 1946 that the world’s first fully digital computer, the ENIAC (Electronic Numerical Integrator and Computer), was unveiled. Six of the ENIAC programmers were the women seen in the second photo, above left. See Lucy Sanders February 14th blog on this event and its connection to women in computing.

Thank goodness for HP’s vision in launching the first hand-held calculator, the HP-35, on February 1, 1972. See my February 1 blog on this event for more details. And check out Gordon Bell’s blog on the introduction of the PDP-11 minicomputer on March 13, 1970.

Check out the Engineering Pathway’s educational resources on the history of computing. For more educational resources, see our electrical engineering education, computer science education and computer engineering education community pages. The Engineering Pathway also hosts Engineering Education communities in all ABET-accredited disciplines.