About IBM’s Automatic Sequence Controlled Calculator (Mark I)
IBM’s Automatic Sequence Controlled Calculator, also called the Mark I, was completed in 1944 after six years of development with Harvard University. It was the first machine that could execute long computations automatically. Over 50 feet long, 8 feet high, and weighing almost 5 tons, the Mark I took less than a second to solve an addition problem, but about six seconds for multiplication and twice as long for division — far slower than any pocket calculator today.