TITLE
    Macintosh: How to Reset PRAM and NVRAM
Article ID:
Created:
Modified: 		2238
6/2/87
8/24/00
TOPIC

    This article explains how to reset the Parameter RAM (PRAM) or Non-volatile RAM (NVRAM) on Macintosh computers.

DISCUSSION

    Resetting PRAM and NVRAM on Power Macintosh, iMac, and iBook Computers
      1. Shut down the computer.
      2. Locate the following keys on your keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 3.
      3. Press the Power button, then hold down the Command-Option-P-R key combination. You must press this key combination before the gray screen appears.
      4. Hold the keys down until the Macintosh restarts itself twice.
      5. Release the keys after the Macintosh restarts twice.
      6. The parameter RAM and the non-volatile RAM in your computer is reset to the default values. The clock setting are not changed.


    Resetting PRAM on PowerBook computers

    Resetting, or zapping, the Parameter RAM (PRAM) when the computer is shut down also resets the power manager.

    For a description of how to reset the power manager and PRAM in your PowerBook, refer to the following Knowledge Base article:

    Article 14449: " PowerBook: Resetting Power Manager. "


    Resetting PRAM on Non-PCI Power Macintosh Computers

    System 6.x
      1. While opening up the Control Panel, hold down the Command, Option and Shift keys.
      2. An alert appears asking if you want to clear parameter RAM; click Yes. A few seconds later, the Control Panel opens.
      3. Close the Control Panel.
      4. Restart your computer.
      5. Parameter RAM is reset, however the clock is not reset. Restarting is necessary to complete this operation. After restarting your computer, you can reset your options using the control panel.

    System 7.x and later
    Important : These steps do not apply to the PowerBook 5300, PowerBook 190, PowerBook 1400, or PCI-based Power Macintosh computers. See sections below for applicable steps for these computers.
      1. Locate the following keys on your keyboard: Command, Option, P, and R. You will need to hold these keys down simultaneously in step 2.
      2. Restart your Macintosh and hold down the Command-Option-P-R key combination. You must press this key combination before the Welcome to Macintosh screen appears.
      3. Hold the keys down until the Macintosh restarts itself twice.
      4. Release the keys after the Macintosh restarts twice.
      5. The parameter RAM in your Macintosh is reset to the default values. The clock setting are not changed.


    Contents of PRAM

    Contents of Parameter RAM are as follows. Some Macintosh computers may not have all the settings described below.
    • Status of AppleTalk
    • Serial Port Configuration and Port definition
    • Alarm clock setting
    • Application font
    • Serial printer location
    • Autokey rate
    • Autokey dela
    • Speaker volume
    • Attention (beep) sound
    • Double-click time
    • Caret blink time (insertion point rate)
    • Mouse scaling (mouse speed)
    • Startup disk
    • Menu blink count
    • Monitor Depth
    • 32 Bit addressing
    • Virtual Memory
    • Ram Disk
    • Disk Cache

Document Information
Product Area: Mac OS System Software
Category: General OS
Sub Category: General Topics

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