What are the typical features of the von Neumann architecture? $(3)($a$)$ Programs cannot be modified while the processor is running. $($b$)$ Data and programs share the same address space. $($c$)$ Programs have to be written in assembly language. $($d$)$ Each machine instruction contains the address of the next instruction. $($e$)$ The processor has a special register called the program counter $($PC$)$