Troubleshooting Multiple Display Support
If the secondary display does not have any output:
- Make sure that this device has been selected in the Control Panel – Display – Monitor – Use this device.
- Make sure the correct video driver is chosen for the secondary video adapter.
- Make sure the secondary adapter is displaying the "Windows has identified…" screen during boot. If not, check device manager for the status of the video adapter.
- Physically switch the order of the adapters in the PCI slots. (This requires the primary display must also qualify as a secondary display.)
If "Extend my Windows desktop onto this monitor" is grayed out:
- Make sure that the secondary display is highlighted in the Display properties.
- Check the number of colors in use - make sure it is greater than 16.
- Make sure you have a supported card as the secondary.
- Make sure that you are not using a Windows 3.1 driver for the primary
- Check to see you are not using an ISA, VLB, or MCA card as the primary
- Check to see if any third-party display control panels are installed.
- Make sure the secondary display adapter is a supported chip set.
- Make sure the secondary display has been detected.
If an application is having problems with Multiple Display Support:
- Try the application on the primary display.
- Run the application full screen
- Disable the secondary device to see if the issue is specific to Multiple Display Support
- Test functionality with Windows 98 provided applets. (Paint, WordPad...)
Under some circumstances, you will not see more than one monitor on the Settings tab of the Display Properties dialog box. Sometimes you cannot use the additional display(s) as part of your desktop for some other reason.
Certain problems can occur when you use on-board PCI video with additional displays:
- The PCI motherboard video is hidden from enumerator and may be identified incorrectly.
- Some systems vendors hide the motherboard video from PCI when another video card is detected in the system. If Plug and Play cannot find the device, Setup cannot start it. If you have this particular problem, there is nothing you can do. To determine whether you have this problem, double-click the System control panel, and then click the Device Manager tab. If only your add-in card is shown as present and working, this is likely to be your problem.
- Windows 98 cannot read the ROM from a motherboard video device. It may be possible to overcome this problem for now if you set up Windows 98 without any other display adapters in the computer. See the preceding section, "Enabling Multiple Display Support," for Setup instructions.
The primary display is using the VGA driver or a Windows 3.x driver.
- If the driver used for the display is a Windows 3.x driver or a standard VGA driver, no secondary displays will function. The standard VGA driver is used whenever the desktop resolution is 640x480 and the color depth is 16 colors.
Absolute pointing devices
- Absolute pointing devices work only on the primary display.
My system won't boot with two video cards installed or the second comes up with a "code 12" in device manager
- If this happens in a system, try moving all the video cards need to the slots that are closest to the motherboard. This is a system BIOS bug and the motherboard manufacturer needs to be notified.
I'm getting a yellow bang on one of my video cards in device manager that says the region of memory that the video card uses is in use.
- Some laptops allow you to specify where the region of memory used by the video card is located in the system BIOS. Set this to "C000-CFFF", or the largest range possible that begins at C000.
- Try removing EMM386.EXE, or set the following under the [386enh] section of system.ini: 3. Emmexclude C000-CFFF
My card is on the supported card list, but Device Manager says that my card will not work with Multiple Display Support.
- Make sure that you are using the right driver, as listed at the beginning of this document.
My screen goes black during boot, or my system hangs. The Windows bootlog option shows the problem occurred in GDI. A box pops up on my screen saying that a fatal exception has occurred in GDI.
- Please contact the provider of your video card for an updated driver.
Application Compatibility and Multiple Display Support
Most applications will not need to be changed to work with Multiple Display Support. Applications work as if there is only one display - for example, dialog boxes that are displayed centered on the screen do not span two monitors.
Full-screen applications will initially appear automatically on the primary display. However, you can move the application to a secondary display and maximize it there. When you re-enter the application, it will appear maximized (full screen) on the secondary display.
The User component in the operating system automatically handles minimum and maximum settings for the display.
However, some applications do not like to be placed in negative space and some applications clip or center windows to the primary monitor. Most applications will display correctly without problems; in the worst case, a particular application might need to run on the primary display only and therefore will require disabling the secondary display.
The following types of applications may have major functionality issues with Multiple Display Support:
- Drivers or applications that patch Gdi.exe or the display driver
- Applications that use Adobe Type Manager
- Remote control applications such as PC Anywhere and Co-Session.
Any other application issues that exist should be of a nuisance type problem, such as dialogs popping up on the wrong screen and dialogs being displayed across two screens, rather than inoperablility-type issues.
GDI – DDML (Display Driver Management Layer)
Windows 98 has changed the code in GDI to support Multiple Display Support. A new set of APIs, collectively known as the Display Driver Management Layer, has been added to GDI. It is this layer that manages the communication between the two adapters making the underlying architecture invisible to applications.
The display Driver Management Layer is responsible for the following:
- Making multiple display drivers look like a single device to GDI
- Ensuring the driver only gets its own drawing commands (X,Y) based
- Allowing each device to have a different size (left/right of primary display)
- Allowing each device to be a different color depth or resolution