EDSAC 2 was an early vacuum tube computer (operational in 1958), the successor to the Electronic Delay Storage Automatic Calculator (EDSAC). It was the first computer to have a microprogrammed control unit and a bit-slice hardware architecture. First calculations were performed on the incomplete machine in 1957. Calculations about elliptic curves performed on EDSAC-2 in the early 1960s led to the Birch and Swinnerton-Dyer conjecture, a Millennium Prize Problem, unsolved as of 2024. And in 1963, Frederick Vine and Drummond Matthews used EDSAC 2 to generate a magnetic anomaly map of the seafloor from data collected in the Indian Ocean by H.M.S. Owen, key evidence that helped support the theory of plate tectonics. EDSAC-2 was decommissioned in 1965, having been superseded by the Titan computer.