PRAM and PMU

Discussion in 'Macintosh Computers' started by mad jew, Dec 15, 2005.

  1. mad jew Moderator emeritus

    mad jew

    Joined:
    Apr 3, 2004
    Location:
    Adelaide, Australia
    #1
    Apple claims that a PRAM reset will automatically reset the Power Manager. I've always assumed this Power Manager to be the PMU but I've seen problems not solved with a PRAM reset yet solved with a PMU reset.

    How is this so? :confused:

    Any help is greatly appreciated, as ever. :)
     
  2. jane doe macrumors 6502

    Joined:
    Feb 18, 2004
    #2

    For most things a PRAM reset will solve. It resets a lot of the PMU settings but does not reset charge/discharge defaults.
     
  3. mad jew thread starter Moderator emeritus

    mad jew

    Joined:
    Apr 3, 2004
    Location:
    Adelaide, Australia
    #3
    Hmm... Okay. Thanks for that.



    Taken from the bottom of this page, just for the record.
     
  4. jane doe macrumors 6502

    Joined:
    Feb 18, 2004
    #4
    "Resetting the parameter RAM (PRAM) when the computer is shut down also resets the Power Manager. The following process resets both the Power Manager and the parameter RAM."

    This is true for the PMU unit on the logic board but is not a full PMU reset. Resetting the PRAM does not force the battery to be polled for charge and there for does not sync the battery charge level/charge indicator.

    The PMU reset will also reset the trackpad optical drive. a NVRAM reset will reset track pad, optical drive, logic board and a few other things.

    On desktop units its called a SMU and does about the same thing (just no battery involved). but it does reset the computers power systems.
     
  5. mad jew thread starter Moderator emeritus

    mad jew

    Joined:
    Apr 3, 2004
    Location:
    Adelaide, Australia
    #5
    Gotcha, thanks for that. I knew the rest of it, just didn't realise there were different scales of Power Manager resetting. :)
     

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