TITLE
    Power Macintosh 9500: Problems With ATI Display Card (11/95)
Article ID:
Created:
Modified: 		18117
7/10/95
11/17/95
TOPIC



    I have a Power Macintosh 9500/120 computer that came with the ATI display card. I have two monitors, a Sony GDM-1932, and a Radius Pressview 21SR. I cannot get either of these monitors to synchronize correctly. Radius has explained that their monitor uses Sync on green. The Sony monitor will sync to other resolutions, but not the 1280x1024.

    Is there a difference in the sense codes for this resolution? Is there a way to get the Radius monitor to work with the ATI display card?

    I have contacted a few manufacturers of display adapters for Macintosh computers, but they have not been able to help me. They claim the 1280x1024 resolution has not been supported on any Apple Macintosh Computers in the past.

DISCUSSION


    The ATI display card does not support sync on green, this is why the Radius monitor does not work properly. However, the workaround section of this article provides some level of support for both your monitors. You also need to purchase a BNC to VGA cable for the Radius monitor before you can use the workaround.

    Normally, on a Power Macintosh 9500 with the standard display card and a non-Apple display (such as a Sony GDM-1932), you would also need a multiple scan display. This display would have to be able to synchronize to 640 x 480 at 60Hz to set up a higher resolution, such as 1024 x 768. Once the higher resolution was set, you could disconnect the multiscan display and connect the non-Apple display. Then the computer would start using the new video scan rate each time the computer is powered on.

    This is because the computer uses sense codes to detect the type of monitor that is connected to it. The computer only starts up at 1280 x 1024 scan rates after you set the Monitors control panel and the settings are stored in PRAM. With no setup information in PRAM, the computer starts at the best scan rate and resolution for the detected display (usually 640 x 480). If you do not have an Apple display to use for setup, you must use a workaround to set the Monitors control panel to the 60Hz scan rate.


    Workaround
    ==========

    Step 1
    ------
    Using a display adaptor, set the display type to VGA/SVGA. (This is 'G' for the video adaptor from Enhance Cable Technology.) Starting up the Macintosh computer with the display adaptor attached between the display and the Macintosh video port starts by default at 640x480 at 60Hz resolution.

    Step 2
    ------
    Open the Monitors control panel. Normally, the control panel Options button only allows safe operating resolutions.

    Step 3
    ------
    Hold down the Option key on the keyboard when you select the Options button in the Monitors control panel. The options panel also shows unprotected scan rates that the video card supports.

    Step 4
    ------
    You can select the 1280x1024 @ 60Hz scan rate from the list. The video scan rate changes, depending on whether you have selected Rearrange on Close or Rearrange on Restart on the bottom of the Monitors control panel window.

    Step 5
    ------
    If you have selected Rearrange on Close and you select a scan rate currently not supported by an Apple display, you are prompted with a dialog box that asks if the monitor display is correct. The dialog only appears if you select an unprotected scan rate.

    If you do not select the OK button within about 10 seconds, the system assumes that you do not have a properly synchronized display and reverts back to the previous scan rate.


    Following the above procedure, you should be able to set your display to the 1280 x 1024 at 60Hz resolution and scan rate. Please contact Enhance Cable Technology for additional information.


    NOTE:
    This article provides some information about a non-Apple product. Apple Computer, Inc. is not responsible for content referring to that product. Please contact the vendor, Enhance Cable Technology, 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.


    This article was published in the "Information Alley":
    Volume II, Issue 9, Page 12


    Article Change History:
    17 Nov 1995 - Reviewed.
    26 Sep 1995 - Added Info Alley information; updated article.
    24 Aug 1995 - Added information on sync on green.

    Support Information Services

Document Information
Product Area: Computers
Category: Power Macintosh
Sub Category: Power Macintosh 9500
Keywords: kppc,kpci,supt,kalley

Copyright © 2000 Apple Computer, Inc. All rights reserved.