Shut down,
Power on and
immediately hold down the Option Key.
From your description, you are putting the DVD in way too late for it to be seen by the system.
P
Hello to all that may be able to assist,
I am having a devil of a time trying to get OSX 10.4.7 (which I have the 2 start up disks for) on to my Mac Mini (late 2006 model: 166/2x256/60/combo/ap/bt). I only have a PC's USB mouse and keyboard to use with the system, which worked fine when an operating system was still on the computer.
I believe that one of my son's friends wiped the OS off of the hard drive by "accident". At least that's my best guess at the reason for this issue. But there may be some other underlying problem that I'm unaware of. I'm mainly a PC user and the only reason for getting an Apple/Mac was ease of use for my son. I came home to it not booting fully and prompting me as if it was factory fresh (but without an OS). I have looked online, tried several options and found nothing that helps.
Here's what I've tried so far:
1) When I first noticed the problem the computer would start up and go through the white background, then grey apple with loading "gear", to an animated multilingual welcome message, to a loading bar, and then to a screen that identified my non-Mac keyboard, then to Mac user id screen, to a file/partition transfer screen, and finally to another screen concerning my keyboard and country where it sits for hours if I let it.
2)First off I tried to start up in safe mode by holding the "shift" button. Nothing happened.
3) I tried repair disk by holding down the "command" and "R" buttons. Nothing happened.
4) I tried to use the start up manager to specify an OS by holding the "option" key. When the start up manager finally came up there was a picture of a HDD without an OS listed below, there was just the picture and an arrow below it.
5) At this point I thought that the OS was fairly well done for and decided to put the start up disks to use. As soon as the start up chime sounds I put in the disk and hold the "C" button, wait for the apple and gear, but before they come up the disc is ejected (I've tried both disks).
So now I'm down to resetting the NVRAM or PRRAM as the only other option that I can find on the web that sounds promising, however I'm not sure that option is best. I'm about at wit's end with this machine! Can anyone help?
Thanks,
Mac_Noobie
P.S. Sorry for the long explanation, but I was hoping to weed some of the simple answers.

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