<P> It was finally delivered to the U.S. Army's Ballistics Research Laboratory at the Aberdeen Proving Ground in August 1949, but due to a number of problems, the computer only began operation in 1951, and then only on a limited basis . </P> <P> The first commercial computer was the Ferranti Mark 1, built by Ferranti and delivered to the University of Manchester in February 1951 . It was based on the Manchester Mark 1 . The main improvements over the Manchester Mark 1 were in the size of the primary storage (using random access Williams tubes), secondary storage (using a magnetic drum), a faster multiplier, and additional instructions . The basic cycle time was 1.2 milliseconds, and a multiplication could be completed in about 2.16 milliseconds . The multiplier used almost a quarter of the machine's 4,050 vacuum tubes (valves). A second machine was purchased by the University of Toronto, before the design was revised into the Mark 1 Star . At least seven of these later machines were delivered between 1953 and 1957, one of them to Shell labs in Amsterdam . </P> <P> In October 1947, the directors of J. Lyons & Company, a British catering company famous for its teashops but with strong interests in new office management techniques, decided to take an active role in promoting the commercial development of computers . The LEO I computer became operational in April 1951 and ran the world's first regular routine office computer job . On 17 November 1951, the J. Lyons company began weekly operation of a bakery valuations job on the LEO (Lyons Electronic Office). This was the first business application to go live on a stored program computer . </P> <P> In June 1951, the UNIVAC I (Universal Automatic Computer) was delivered to the U.S. Census Bureau . Remington Rand eventually sold 46 machines at more than US $1 million each ($9.43 million as of 2018). UNIVAC was the first "mass produced" computer . It used 5,200 vacuum tubes and consumed 125 kW of power . Its primary storage was serial - access mercury delay lines capable of storing 1,000 words of 11 decimal digits plus sign (72 - bit words). </P>

Describe first generation second generation third generation computers