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# IBM XGA Aperture Problem on PS/2 16 Bit Computers

Article ID: 117394

Article Last Modified on 10/31/2006

APPLIES TO

- Microsoft Windows NT Advanced Server 3.1
- Microsoft Windows NT Workstation 3.1
- Microsoft Windows NT Advanced Server 3.1

This article was previously published under Q117394

## SYMPTOMS

On IBM PS/2 computers with a 16-bit bus, and XGA, the following error message may appear after installing the XGA drivers in Microsoft Windows NT:
The aperture enabled for the xga device is invalid, please enable the 4MB aperture (preferred) or 1MB aperture using the xga reference disk.
This error occurs on 16 MB 16-bit bus PS/2 computers that support a maximum of 16 MB of RAM, such as the model 9556 or 9557.

## CAUSE

The PS/2 XGA subsystem provides three possible apertures, or windows, to video memory in the physical memory address space of the system. Aperture size options are 64KB, 1MB, and 4MB. The 4MB aperture option is not available on 16-bit computers, such as those based on the 80386 SX processor. The 4MB Aperture is also not available if the XGA subsystem is plugged into a 16 bit slot in a 32 bit computer and is only accessible by 32 bit protect mode drivers, such as the drivers used by Microsoft Windows NT.
Currently, Microsoft Windows NT only supports XGA with an Aperture of 1MB, or 4MB enabled. On 16-bit IBM PS/2 computers with 16MB RAM, the 1MB meg aperture cannot be enabled.

## WORKAROUND

According to IBM , a possible workaround is to use the standard VGA which does not require this option to work, or decrease the amount of physical RAM below 16MB.
For more information, contact IBM Tech Support 800/772-2227
The PS/2 computers are manufactured by IBM, a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding this product's performance or reliability.

Additional query words: prodnt xga2

Keywords: kbhardware KB117394