TITLE
    Macintosh Performa 6400: Non-Supported Video Resolutions (8/96)
Article ID:
Created:
Modified: 		20248
8/2/96
8/2/96
TOPIC


    I have a Macintosh Performa 6400 series computer and I am confused by the resolutions available to me using the AppleVision 1710AV Display. The Technical Information Guide provides a list to me, but there are more available to me. Why?

DISCUSSION


    There are two supported resolutions using the Macintosh Performa 6400 series computer with the AppleVision 1710AV display; 832x624 75Hz, and 640x480 67Hz.

    When you use the Display control panel other VGA/SVGA resolutions appear in italics.

    When using the Macintosh Performa 6400 Series computer with most Apple displays, there will be more resolutions available than what the display supports. All non-supported resolutions appear in italics.

    These multiple resolutions are available to support a larger number of Apple and non-Apple multiple scan displays. You should check the technical information for the display you have to confirm which resolutions are supported by your display. Although some Apple displays may also work with non-supported resolutions, their performance is not optimal.

    The Macintosh Performa 6400 supports resolutions up to 1024x768 72Hz (maximum). Although some Apple Multiple Scan displays support higher resolutions, 832x624 or 1024x768 will be the highest resolution available depending on which multiple scan display is used.

    Using Non-Macintosh Resolutions
    ===============================

    When you select a non-Macintosh resolution (VGA/SGVA resolution), a dialog appears asking you to confirm the display image is OK. If you select OK, the new resolution is selected. If you do not select OK, the Mac OS reverts to previous resolution after a few seconds. This is done in case an incompatible video resolution is selected. The dialog does not appear if you select a standard Macintosh video resolution (640x480 67Hz or 832x624 75Hz).

    Some resolutions will display "scrambled", distorted, large, small, or no image. This may happen when an unsupported resolution for a particular display is selected in the Displays control panel. If the image is stable but the performance of the image is not acceptable, one of the supported video resolutions should be used for the particular display connected to the Macintosh Performa 6400 computer.

    If a resolution has been selected that produces an unusable image on the display and are not able to select another resolution in the control panel or control strip, you need to reset the Non-volatile RAM (NVRAM).


    Resetting NVRAM
    ===============

    Turn off your Macintosh Performa 6400 or Choose Shut Down from the Special menu.

    NVRAM can be cleared by holding down the Command-Option-P-R keys simultaneously as soon as possible after hitting the power-on key. It happens BEFORE you see the gray screen. Once the gray screen appears, the PRAM is cleared at the same point as it was in previous machines.

    One very important difference is that NVRAM is not cleared during a warm or soft restart (by selecting Restart from the Special menu), whereas PRAM is cleared in that case.

Document Information
Product Area: Computers
Category: Power Macintosh
Sub Category: Macintosh Performa 6400

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