The first known attempt at an electronic digital computer, designed in 1936–38 by John Atanasoff, a mathematics professor at Iowa State College, primarily for the solution of linear algebraic equations. It was built by Atanasoff and his assistant Clifford Berry, using vacuum tubes (valves) as the logic elements, but was never fully operational and was abandoned in 1942. Atanasoff’s ideas were used by Mauchly in his design of ENIAC. A replica has been constructed by Iowa State University and was first demonstrated in 1997.