I am not too familiar with the computer architecture terminology yet so please bear with me. I seem to understand that von Neumann architectures are more robust ("universal Turing machines") as opposed to Harvard architectures, but don't know too much about the details yet.
After spending the past few nights looking into the Call Stack, I am still confused. I also have seen a few papers here and there (just scanning the abstracts for the moment), such as Programming Without a Call Stack, and others, which makes me wonder if there are any systems / architectures for defining a virtual machine without a call stack. I don't really know what it would look like, but maybe there are some things to check out. I am not talking about simple machines, like those from the pre-1960's era which didn't have recursion and so didn't need call stacks I guess. I am talking about fully robust / complete computer architectures which use something other than a call stack.