Pc professionals should have good reasoning and logical downside fixing skills, be observant, alert to detail and tenacious in pursuing problems to completion. The Selective Sequence Digital Calculator (SSEC) venture, led by IBM engineer Wallace Eckert, makes use of both relays and vacuum tubes to process scientific information at the rate of 50 14 x 14 digit multiplications per second. Earlier than its decommissioning in 1952, the SSEC produced the moon place tables used in early planning of the 1969 Apollo XII moon landing. These tables had been later confirmed by utilizing extra modern computer systems for the precise flights. The SSEC was one of many last of the generation of ‘tremendous calculators’ to be constructed utilizing electromechanical expertise.