How to force Fedora 12 to start to text mode?

When you first start your computer, the GRUB screen (where you choose your Operating System) appears. Select the Fedora that you want to boot into, but press the a key instead of pressing Enter.

You will see a line somewhat like the following:

kernel /vmlinuz-2.6.9-1.667 ro root=LABEL=/ acpi=on rhgb quiet

Add the number of your runlevel to the end of that line, and then press Enter. For example, to boot into text-only mode, the line would look like:

kernel /vmlinuz-2.6.9-1.667 ro root=LABEL=/ acpi=on rhgb quiet 3

You will then boot into the new runlevel this time only.

More about runlevels: http://www.fedorafaq.org/basics/#runlevel

Hold down Ctrl when booting to show the GRUB menu. Then select the kernel you care about, hit A, remove rhgb if it shows on the line, then go to the end and type Space3Enter.