The Electronic Discrete Variable Automatic Computer (EDVAC), an outgrowth of the work on the ENIAC computer during the war, was one of the earliest large mainframe computers to be built in the 1940s, and was the first to represent binary rather than decimal systems. Without the original project leaders Presper Eckert and John Mauchly however (who had left the project to start their own business), and others who had returned to university appointments, those at the Moore School struggled without the same level of intellectual resources - apparent in the report in the second work here. In the first paper Irwin reports that the EDVAC would be available for astronomers towards the end of 1948. In actuality the machine was late in delivery to the Ballistics Research Laboratory in Maryland and did not run its first successful application until 28 October 1951. EDVAC had almost 6,000 vacuum tubes and 12,000 diodes, consumed 56 kW of power, covered 45.5 m² of floor space and weighed 7.8 t), requiring an operating personnel of 30 people per eight-hour shift.
In his famous monograph First Draft of of a Report on the Edvac John Von Neumann proposed the main enhancement to its design that established the "stored-program" concept that we now call the Von Neumann architecture. This was the storing of the program in the same memory as the data. The British computers EDSAC at Cambridge and the Manchester Baby were the first working computers that followed this design, repeated by almost all computers made since.