TITLE
    Power Macintosh: Video Blinking At Startup (10/96)
Article ID:
Created:
Modified: 		18012
6/26/95
10/16/96
TOPIC




    I noticed when my Power Macintosh 9500 series computer is starting up that the screen blinks off and on for a second during the startup process. Is this normal or is there something wrong with my computer?

DISCUSSION



    The video blinking or flash is normal behavior for a PCI-based Power Macintosh computer and does not indicate a hardware problem. The flash will occur on Power Macintosh 7200/7500/8500/9500 computers.

    The reason that the video goes blank for a short time at startup is the video card initially uses the driver contained on the ROM of the video card. Early in the startup process, a newer video driver is swapped in from either the Graphic Accelerator extension in the 9500 series or ROM of the 7200/7500/8500 series computers. It is during the swapping of the video driver that the flash occurs. This is normal.

    A consequence of the new driver loading is if you have installed a custom StartupScreen in the System Folder, the system will startup with the custom screen, flash, and then display a grey screen for the rest of the startup sequence. At the time of this article, it is not possible to get a startup screen to remain visible throughout the startup process.

    You can verify the driver swap is causing the issue you are experiencing by forceing the Power Macintosh to use the first video driver contained in ROM. This is done by holding down the Command-Shift-N-D keys at startup. You will notice that the video 'blanking' does not occur because the video driver is not being swapped.

    This troubleshooting tip can be helpful for a couple of reasons:

    * It can be used to demonstrate that the video driver is actually being swapped because it does not 'blink' when the video driver on ROM is used.

    * If the 'software' video driver on the Power Macintosh 9500 is corrupt for some reason you can revert back to the video driver in ROM to determine where the problem might be (that is, it can be corrupt software or a bad card).

    IMPORTANT: Since the video driver in the "Graphic Accelerator" extension contains a newer video driver, you should only bypass this video driver for troubleshooting purposes. Running the system off the ROM based video driver continually may produce unpredictable results.


    This article was published in the "Information Alley":
    Volume I, Issue 8, Page 5


    Article Change History:
    16 Oct 1996 - Reviewed for technical accuracy.
    27 Sep 1995 - Updated to identify issue on all PCI-based Computers.
    28 Aug 1995 - Added Info Alley information.



Document Information
Product Area: Computers
Category: Power Macintosh
Sub Category: General Topics

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