This is a great tip that we are sharing with owners of old Apple Mac computer who has forgotten firmware password on older Apple iMac (2009 models or older).
If your Apple iMac powers on and shows a padlock icon asking for password, it has firmware password lock on it. You can remove this firmware password by following this simple instructions:
- Access the RAM slots at the bottom of the iMac
- Remove one RAM stick to make the hardware configuration different
- Power on your iMac, and do a PRAM reset by immediately press and hold Option-Command-P-R
- You should hear a boot Apple chime within a few seconds
- Keep holding those same 4 keys, until you hear the boot chime 3 more times
- Release those keys and turn off your iMac
- Reinstall the RAM stick that you removed earlier
- Boot the computer normally and the firmware password should have been removed!
Enjoy your old much loved Apple iMac!