A Really Big Computer

On Monday, August 7, 1944, the IBM Automatic Sequence Controlled Calculator, designed and built by Howard Aiken with funding from IBM, was dedicated at Harvard University, where it was called the Mark I.  Used by the U.S. Navy Bureau of Ships for gunnery and ballistic calculations, it was an electro-mechanical computer 51 feet long, 8 feet high, and 2 feet deep, using 500 miles of wire with three million connections.

The Mark I read its instructions from a punched paper tape and executed the current instruction and then read in the next one.  A loop was accomplished by joining the end of the paper tape containing the program back to the beginning of the tape (literally creating a loop).  One of the first programmers of the Mark I was Grace Hopper.  I once had the pleasure of hearing her speak at a computer conference.

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