Von Neumann was a founding figure in computer science.[49] Von Neumann's hydrogen bomb work was played out in the realm of computing, where he and Stanislaw Ulam developed simulations on von Neumann's digital computers for the hydrodynamic computations. During this time he contributed to the development of the Monte Carlo method, which allowed solutions to complicated problems to be approximated using random numbers. He was also involved in the design of the later IAS machine.
Because using lists of "truly" random numbers was extremely slow, von Neumann developed a form of making pseudorandom numbers, using the middle-square method. Though this method has been criticized as crude, von Neumann was aware of this: he justified it as being faster than any other method at his disposal, and also noted that when it went awry it did so obviously, unlike methods which could be subtly incorrect.
While consulting for the Moore School of Electrical Engineering at the University of Pennsylvania on the EDVAC project, von Neumann wrote an incomplete First Draft of a Report on the EDVAC. The paper, whose public distribution nullified the patent claims of EDVAC designers J. Presper Eckert and John William Mauchly, described a computer architecture in which the data and the program are both stored in the computer's memory in the same address space.[50]
John von Neumann also consulted for the ENIAC project, when ENIAC was being modified to contain a stored program. Since the modified ENIAC was fully functional by 1948 and the EDVAC wasn't delivered to Ballistics Research Laboratory until 1949, one could argue that ENIAC was the first computer to use a stored program. John von Neumann also designed the instruction set for the modified ENIAC, and he should be given credit for this. The stored program version of ENIAC ran 6 times slower, but it was still entirely I/O bound, and