Evolution of electronic digital computers. The 'computer tree' shows the evolution of electronic digital computers, taking ENIAC (Electronic Numerical Integrator And Computer) to be the first such machine. ENIAC was designed by the University of Pennsylvania in the 1940s for the US Army's Ballistic Research Laboratory, to solve ballistic calculations. From ENIAC and her successors, EDVAC and ORDVAC, the tree traces the developments in computers through the 1940s and 50s. EDVAC and ORDVAC are shown on separate limbs to differentiate between serial computers (like EDVAC), which evolved into business machines, and parallel computers (like ORDVAC), which were more commonly used for scientific research.