The von Neumann machine architecture is a computer organization based on a 1945 description by the mathematician John von Neumann. That document describes a design architecture of four components connected by a communications channel, the system bus.
Stored Program Computer
John von Neumann also proposed, in the late 1940s, that a program be electronically stored in binary-number format in memory, the same as the data.
In earlier computers, data was stored in RAM but the program was changed by setting switches and inserting patch cables. In effect, the machine had to be rewired to change the program.