<P> The idea of a stored - program computer was already present in the design of J. Presper Eckert and John William Mauchly 's ENIAC , but was initially omitted so that it could be finished sooner . On June 30 , 1945 , before ENIAC was made , mathematician John von Neumann distributed the paper entitled First Draft of a Report on the EDVAC . It was the outline of a stored - program computer that would eventually be completed in August 1949 . EDVAC was designed to perform a certain number of instructions ( or operations ) of various types . Significantly , the programs written for EDVAC were to be stored in high - speed computer memory rather than specified by the physical wiring of the computer . This overcame a severe limitation of ENIAC , which was the considerable time and effort required to reconfigure the computer to perform a new task . With von Neumann 's design , the program that EDVAC ran could be changed simply by changing the contents of the memory . EDVAC , however , was not the first stored - program computer ; the Manchester Small - Scale Experimental Machine , a small prototype stored - program computer , ran its first program on 21 June 1948 and the Manchester Mark 1 ran its first program during the night of 16 -- 17 June 1949 . </P>
who developed the central processing unit ( cpu )
John von Neumann