Windows 95/98

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Windows 9X Devices

Overview – Multiple Display Support

Windows 98 now supports both multiple video cards and video cards that have multiple outputs. This increases the usable desktop area and allows customers to keep applications open on different screens or expand them across multiple screens.

If you have a PCI computer with two or more PCI display adapters and monitors, you can take advantage of Multiple Display Support. You can, for example, click an HTTP link while you read e-mail and have the browser start on an adjacent monitor. Or you can play a game using different monitors for left, right, and center perspectives or as separate instrumentation consoles. Multiple display support can also be used for desktop publishing, presentations with notes, or as a way to expand the desktop.

Configurations have been successfully tested up to nine monitors (such as a 3 x 3 grid), although two or three are normally encountered.

Multiple Display Support is a set of related features that support the use of more than one display device at a time. Additional application programming interfaces and device driver interfaces are provided under Microsoft DirectX version 5.0.

The user interface has been modified to recognize a desktop that spans multiple monitors, with no restrictions on size or position. For monitors attached to the same system but showing different images simultaneously, the different displays may have differing (x,y) resolution and refresh rates, as well as differing display capabilities.

To support this capability, new APIs in the Win32 API set enable any application to take advantage of multiple monitors. Applications do not need to be modified to work on a computer with multiple monitors, but application developers can take special advantage of this feature by calling the new APIs.

• In troubleshooting On-Now and ACPI, first thing to ask the customer is "Does the machine support the ACPI specification?" ACPI requires changes in both the BIOS and the chipset on the motherboard for full implementation.

Hardware Requirements

Multiple Display Support uses the concept of primary and secondary displays. The hardware requirements for the two display types are the same. Both video display adapters must be PCI or AGP devices. The ability to change these types of device’s resources is what allows Windows 98 to work with two display adapters.

With Multiple Display Support, the operating system still needs a PCI VGA device, which becomes the primary display. The system BIOS picks the primary VGA device based on the PCI slot order — unless the BIOS offers an option for picking which device is to be treated as the VGA device. The VGA device cannot be stopped, which is an important consideration for docking units, such as the CP family with the C/Dock Expansion Replicator.

Note: Some laptops when "Hot docked" into a docking station that contains a display adapter will disable, or turn off, the laptop’s built in display. With the CP family and the C/Dock, using A04 for the CP or A00 for the Cpi, this feature is not an issue. The BIOS has been written to allow for the C/Dock PCI card to be primary and the Neomagic video to be secondary.

AGP Graphics

AGP (Accelerated Graphics Port) is a specification from Intel that boosts the performance and quality of accelerated 3-D graphics. AGP is a local bus that directly connects your graphics hardware to the CPU and system memory. This bypasses the PCI bus.

AGP graphics cards plug into an AGP slot. Graphics running through the AGP bus move about four times faster than a PCI bus graphics card. Microsoft is supporting AGP in DirectX 5.0 APIs. 3-D software gets the biggest benefit since programs can use the main system memory to store the 3-D graphics.

AGP graphics cards connect directly to the system chipset over a 64-bit AGP bus. The bus runs at 66 MHz, and is designed to handle two transactions per clock cycle. If your system has both, a PCI and AGP card, the PCI card will generally be seen first and acts as the primary display card but is dependant upon how the system will initialize the video subsystem.

Display Chipset

Primary Display

These cards cannot be used in Multiple Display Support:

  • Permedia (not including the Permedia-2)

  • PSA/EISA cards

Primary and Secondary Display

The primary and secondary display, and all display adapters thereafter must be one of the following chipsets and use a DirectX 5.0, Multiple Display Support enabled, display driver (included in Windows 98):

  • ATI Mach64 GX

  • S3 764V+ (765), Trio 64V2

  • S3 ViRGE

  • S3 Aurora (S3M65)

  • Cirrus 5436,7548,5446

  • ATI Rage 1 and 2 (VT and greater)

  • ATI 3D Rage Pro

  • Trident 9685/9680/9682/9385/9382/9385-1 PCI

These drivers have DirectDraw support:

  • ATI Mach64

  • S3 ViRGE

This driver has Direct3D support:

  • S3 ViRGE

Note: The list above are supported chipsets not display adapters. There are currently several display adapters that use the S3 ViRGE chip and all are Multiple Display Support capable with the appropriate display driver.

Customers can freely mix and match display hardware because the graphics adapters do not need to be identical. Each display device and monitor combination is separately enumerated and configured and can have completely different screen characteristics. This means that each monitor can have different resolutions and color depths. For example the primary display might be set for 1024x768x256 while the secondary is set to use 800x600x32K

Enabling Multiple Display Support

Multiple Display Support requires that all of the display adapters be PCI or AGP devices. The setup instructions vary according to the following two scenarios:

Onboard display chipset and display adapter

Follow these instructions when your motherboard has a PCI or AGP display chipset and you have a second PCI or AGP display adapter to plug in.

  • The built-in display is not the primary display. The computer disables the on-board video adapter at startup time and the add-in card becomes your primary display. This is a function of the BIOS and not something you can control. This occurs when the CP or Cpi is connected to a C/Dock with the Matrox card.

  • It is important to set up Windows 98 the first time with only your on-board video adapter in the computer. If another adapter is present before you start Windows 98 for the first time, Setup cannot initialize your on-board video properly. This should not be an issue coming out of the factory. If the customer has reinstalled the OS then make sure the video is reconfigured to recognize the onboard video.

  • If you follow the instructions and your on-board video does not function correctly as the secondary display, it is likely that Setup is unable to find and read the complete ROM of the adapter to initialize it properly.

If your computer has built-in display chipset on the motherboard, follow these steps exactly when setting up Windows 98:

  1. Run Windows 98 Setup with only the motherboard video in the computer.

  2. After Setup has been completed successfully, shut down, and then install additional display adapters.

  3. Start the computer.

  4. In Control Panel, double-click Display, and then click the Settings tab.

  5. Select the adapter/monitor combination from the Display dialog box, and then select the display you wish to enable.

  6. Click the Extend my Windows desktop on to this monitor check box.

Two separate plug-in display adapters

If all the display adapters you want to put in your computer are on add-in cards (that is, none of the display adapters in the system are on the motherboard or built in), you can install all of them before setting up Windows 98.

If your computer has two plug-in PCI display adapters follow these steps exactly when setting up Windows 98:

  1. Run Windows 98 Setup with both display adapters in the computer.

  2. In Control Panel, double-click Display, and then click the Settings tab.

  3. Select the adapter/monitor combination from the Display dialog box, and then select the display you wish to enable.

  4. Click the Extend my windows desktop on to this monitor check box.

Multiple Display Support Configuration

When implemented in a PC system, Multiple Display Support can be configured as multiple monitors, each connected to its own graphics adapter, or as multiple monitors connected to a single adapter that supports multiple outputs. Under either configuration, each display device can have different sizes or positions, and each device can use a different color depth.

Increasing Screen Real Estate

Multiple Display Support uses the concept of a virtual screen, where each monitor displays a piece of the larger virtual screen. The upper left corner of the primary display is considered X, Y point 0,0. This means that in the configuration shown above, any application that is being displayed on Display2 is being run in negative space. Negative space is where the X, Y coordinates are less than zero. This may cause some application compatibility issues.

The most common scenario is shown below using two screens with the secondary display extending the desktop to the left.

Tip: When troubleshooting application issues, try running the application in the primary display. Also test with the applets that come with Windows 98 (i.e. Paint, Wordpad…)


To change the order of the monitors go to the Control Panel – Display – Settings tab. The size of the monitor on the screen will give an indication of the resolution that the adapter is using. The larger the screen, the higher the resolution. In the example below you can see that monitor one is running at 1024x768 while monitor two is running at a lower resolution. To see the resolution click the Display drop down list box and select the second display.

The picture of the monitors above is a virtual layout of the display. You do not have to physically move the monitors to match the layout above.

Clicking and dragging the picture of the monitor to its desired location will change the monitor positioning on the virtual desktop. Given the example above this configuration will allow a mouse pointer dragged off the left side of Display 1 to appear on the right side of Display 2. This will allow the virtual desktop to be configured to match the physical layout of the monitors.

Clicking the "Advanced" button allows the customer to choose the specific display adapter’s settings (adapter and monitor settings, as well as performance and color management).


The positions of the screens in the control panel dictate the relative positions of the screens to each other. If one screen is located above the other, then the mouse pointer must be moved up or down to reach the other screen.

Undisplayed Graphic