At that time, von Neumann was working on the Manhattan Project, and needed to determine whether implosion was a viable choice to detonate the atomic bomb that would be used a year later.

The Mark I also computed and printed mathematical tables, which had been the initial goal of British inventor Charles Babbage for his analytical engine in 1837.

[4] After a feasibility study by IBM engineers, the company chairman Thomas Watson Sr. personally approved the project and its funding in February 1939.

After two rejections,[5] he was shown a demonstration set that Charles Babbage’s son had given to Harvard University 70 years earlier.

A project conceived by Harvard University’s Dr. Howard Aiken, the Mark I was built by IBM engineers in Endicott, N.Y. A steel frame 51 feet long and 8 feet high held the calculator, which consisted of an interlocking panel of small gears, counters, switches and control circuits, all only a few inches in depth.

The ASCC used 500 miles (800 km) of wire with three million connections, 3,500 multipole relays with 35,000 contacts, 2,225 counters, 1,464 tenpole switches and tiers of 72 adding machines, each with 23 significant numbers.

[11] The Mark I had 60 sets of 24 switches for manual data entry and could store 72 numbers, each 23 decimal digits long.

[15][16][17][18][19] The first programmers of the Mark I were computing pioneers Richard Milton Bloch, Robert Campbell, and Grace Hopper.

Each storage location, each set of switches, and the registers associated with the input, output, and arithmetic units were assigned a unique identifying index number.

[23] John von Neumann had a team at Los Alamos that used "modified IBM punched-card machines"[24] to determine the effects of the implosion.

[24]"Von Neumann joined the Manhattan Project in 1943, working on the immense number of calculations needed to build the atomic bomb.

[26][page needed][27] Aiken, in turn, decided to build further machines without IBM's help, and the ASCC came to be generally known as the "Harvard Mark I".

IBM went on to build its Selective Sequence Electronic Calculator (SSEC) to both test new technology and provide more publicity for the company's efforts.

[citation needed] The Mark I was disassembled in 1959, and portions of it went on display in the Science Center, as part of the Harvard Collection of Historical Scientific Instruments.