There are minor differences between ex4 and ex5. There are minor differences between ex5 and ex6. There are minor differences between ex6 and ex7. There are many possible interface techniques. Many of the currently common methods are still very reminiscent of the desktop metaphor interfaces.
Text is also a possible interface.
One that allows other possible interfaces to specify functions to the world simulation. Pressing keys on the keyboard is the simplest example of this. The ubiquitous 'ESC' key is one example Some applications also read keyboard presses to change modes, etc. Text commands can also be sent via a socket connection. There are some significant differences between ex7 and ex8.