TITLE
    Macintosh: Using 1280x1024 60Hz Resolution (2/96)
Article ID:
Created:
Modified: 		18367
8/11/95
2/8/96
TOPIC


    How can I set a non-Apple display, which is connected to a Macintosh computer, to a resolution of 1280x1024 60Hz. My user's guide states that my Macintosh computer should support this VGA display at this setting.

DISCUSSION


    Sense codes are used so the computer can detect the type of monitor that is connected to the system. The computer only starts up at 1280x1024 scan rates after you have set the monitor control panel and the settings are stored in parameter RAM (PRAM). With no setup information in PRAM, the computer starts at the best scan rate and resolution for the detected display (usually 640x480).

    If your display does not support 640x480, you can usually use a multiple scan display to set the higher resolutions. Once that information is stored in PRAM, you can connect the non-Apple display. Since there are no Apple displays that support 1280x1024 60Hz (the Multiple Scan 20 only supports 75Hz), you must use a workaround to set the Monitor control panel to the 60Hz scan rate.

    NOTE:
    There is a least one third-party company which sells a 60 Hz adapter kit. Using this kit, you can cycle through resolution settings at startup until the proper setting is selected. Using this solution, you do not need to use the workaround provided in this article.

    Using a display adaptor, set the display type to VGA/SVGA. Follow the directions in the display adapter's user's guide for the proper instructions for selecting VGA/SVGA.

    Powering up the Mac with most third-party display adaptors attached between the display and the Mac video port starts up by default at 640x480 60Hz resolution.

    Step 1
    ------
    Open the Monitor control panel.

    Step 2
    ------
    Hold down the Option key while selecting the 'Options' button in the Monitor control panel. (Normally, 'Options' button will only allow 'safe' operating resolutions. If you hold down the option key on the keyboard when you select the 'options' button in the Monitor control panel, the options panel will also show 'unprotected' scan rates that is supported.)

    Step 3
    ------
    Select the 1280x1024 60Hz resolution.

    The video scan rate will change depending on whether you have selected 'Rearrange on Close' or Rearrange on Restart' on the bottom of the Monitors control panel window.

    If you have selected 'Rearrange on Close' and you select a scan rate currently not supported by an Apple display, you will be prompted with a dialog box asking*if the monitor display is correct. If you do not click the OK button within about 10 seconds, the system will assume that you do not have a properly synchronized display and will revert back to the previous scan rate.

    Following the above procedure, you should be able to set your display to the 1280x1024 60Hz resolution and scan rate.

    Display adapters are available from several third-pary companies such as Enhanced Cable Technology, Griffin Technology, and MacAdapt.

    NOTE:
    This article provides information about non-Apple products. Apple Computer, Inc. is not responsible for content referring to those products. Please contact the vendor for additional information.

    The Tech Info Library article titled "Locating Vendor Information" can help you search for a particular vendor's address and phone number.


    Article Change History:
    08 Feb 1996 - Added new information on third-party products.

    Support Information Services

Document Information
Product Area: Monitors-Displays
Category: Non-Apple Display Issues (Third-Party)
Sub Category: General Topics

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