In my maps i only have 4 humans and 4 computers but i need one more computer player can i use p9?
for what u need player 9?...
There are a few things that you can use Player 9 for, but for the most part it won't function like a normal player.
why not ? you can use the SCMD2 or X-tra p9-12 mode
You can place units for them and use triggers for them but other than that, they are pointless because they don't attack.
you can use p9 for neutral and for displaying units. i guess the only way to make player 9 attack is not put a start location for it, but will also disable the triggers from working.
if it can be used it can only be used as neutral i think but i am not positive
you could try changing the control of p9 to human in SCMDraft, but it would most probably crash SC. maybe it won't (that'd be cool

); i dont know.
P9-12 wont work with human control. Ever. I tried.
I beleive certain triggers dont work for players 9-12...
But you can use them, I'm using them in my Godfather map.

Nope, they'll never attack humans.