IBM SSEC

The Selective Sequence Electronic Calculator ( SSEC ) was built in 1946/47, under the guidance of Columbia Professor Wallace John Eckert of the Watson Scientific Computing Laboratory and was a hybrid computer, which consisted of both tubes and 12,500 from 21,400 mechanical relays. He stood at the IBM headquarters in Manhattan and there covered the walls of a 18 × 9 -foot space, according to other sources, a 18, a 12 and a 24 -meter-long wall. On January 27, 1948, he took on the job.

An important task fulfilled SSEC: He averaged Moon positions with which the Apollo landings were made possible. Each position required 11,000 additions and subtractions, 9,000 multiplications and 2,000 search queries to a database. In each calculation, in turn, had to be included 1,600 relationships. This process lasted - to the astonishment of the spectators - seven minutes.

The single piece was dismantled in July 1952 to make room for the new Defense Calculator (IBM 701).

From the technical side ( astronomer Eckert was ) was especially Frank E. Hamilton involved in IBM.