explain von neumann 

Von Neumann Architecture: One of his most influential contributions to computer science is the concept of the "von Neumann architecture," which underpins most modern computers. This architecture consists of a central processing unit (CPU), memory, and input/output devices. In this model, both data and programs are stored in the same memory space, which allows for the flexibility and efficiency of program execution. This was a departure from earlier computing models that used separate memory spaces for data and instructions.