If you're troubleshooting a Mac and aren't sure what exact model it is...so you don't know what firmware this or that needs...there's an easy way to find out not only the model designation but the type of CPU as well.
Fire up the Terminal (From the Finder hit Command + Shift + U, then T, then Command + O) and type in:
sysctl -a hw
Then hit Return.
You'll see fun info like:
hw.availcpu = 2
hw.machine = i386
but most importantly:
hw.model = Macmini2,1
If you want to see the exact CPU type, type in:
and hit Return then look for something like:
machdep.cpu.brand_string: Intel(R) Core(TM)2 CPU T7200 @ 2.00GHz