The datapath and the instruction cycle

On 30 June 1945 John von Neumann circulated a First Draft of a Report on the EDVAC, describing a computer then being designed at the Moore School of the University of Pennsylvania. Its central idea was that instructions should be stored in the same memory as data, as numbers the machine could read, and even modify, like any others.

Earlier machines were set up for each problem with plugboards and switches. A stored-program machine changes task by loading a different program. The organisation the draft described, a processing unit, a control unit and one memory for both, is still called the von Neumann architecture.