IBM 701 Defense Calculator

The IBM 701 Defense Calculator (1952) was IBM's first production computer. It was designed primarily for scientific calculation and included "microsecond circuits installed at critical locations ... to send electrical impulses from one unit to another at a speed faster than one-millionth of a second" devised at Columbia University's Watson Lab. It rented for about $16,000 per month. In all, 19 units were manufactured, most of them for US national laboratories, the US Weather Bureau, aircraft manufacturers, etc, and big companies like GE. The first unit was installed in 1952 at IBM Headquarters in New York City, replacing the SSEC.