Just as Preferences in the Lisa keeps the settings, the Parameter Memory chip or Parameter RAM in the Macintosh maintains system information: Clock, date, and alarm settings, some Control Panel settings, and Serial port configurations.
If necessary, Parameter RAM may be erased entirely:
1. Turn off the Macintosh
2. Unplug the Macintosh
3. Remove the battery (do not try to draw off charge by placing the battery back in upside down)
4. After at least 10 minutes, reinsert battery