Mac OS X: What's stored in PRAM
Summary
This document offers a general overview of what system information is stored in the parameter RAM (PRAM) by Mac OS X. For information about how PRAM affects Mac OS 9 or earlier's control panels and other settings, see this document.
Products Affected
Mac OS
PRAM stores certain system and device settings in a location that Mac OS X can access quickly. Exactly which settings are stored in the computer's PRAM varies depending on the type of computer as well as the types of devices and drives connected to the computer. Parameter RAM is a small area of non-volatile RAM (NVRAM).
Some information stored in PRAM includes:
- Display and video settings such as refresh rate, screen resolution, number of colors
- Startup volume choice
- Speaker volume
- Recent kernel panic information, if any
- DVD region setting
Note: Mac OS X stores your preselected DVD region choice in PRAM for easy access. Resetting PRAM does not allow you to change the DVD region.
Unlike prior versions of the Mac OS, Mac OS X does not store network settings in PRAM. If you experience a network issue, resetting PRAM will not help.
If PRAM is reset, you may need to verify your time zone, startup volume, and volume settings using System Preferences. Certain firmware updates may reset PRAM as a normal part of their installation process.