Answer to "How do you make external display the main display? My diplay is,broken"the osx needs to boot then it may see the ex display ?? now you will need to make it a mirror or the laptop this is hard to do as you will need to see the laptop display.?? make a new disk drive on a bowerbook g4 as this boots on that machine make this a mirror and then put your laptop (t) on boot on the laptop you will see your hard drive open it make it a mirror and then // reboot and it work with you ex display only after osx has booted .