Q: I want to reset NVRAM to factory defaults. How
do I do that?
A: When you start a Macintosh computer you can reset
the configuration variables by holding down the following
keys, "command-option-p-r", without the quotes.
Listen for the second boot beep before releasing the keys
and the configuration variables will be reset. When a Macintosh
computer starts, control is immediately given to what Apple
terms "Hardware Init". This firmware is contained
in ROM and must use the microprocessor registers since memory
is not tested and initialized. When you hear the boot beep
Hardware Init is finished testing and initializing memory
and the microprocessor and passes control to Open Firmware.
Open Firmware checks for keys being pressed. In this case,
command-option-p-r, is detected and Open Firmware resets
NVRAM and then passes control back to Hardware Init which
will generate another boot beep. Don't worry if you hold
down the keys too long and hear more than two boot beeps.
More than two boot beeps will just reenter the startup sequence
more times which will not cause any harm.
[Dec 21 2001]
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