ATI Graphics Ultra Pro or Plus Defaults to VGA

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The Memory Aperture feature on the Graphics Ultra Pro and Plus products moves the video frame buffer into the motherboard system memory address space to improve performance. While not required to access the color and resolution capabilities of these graphics accelerator products, it does improve performance.

386- and 486-based ISA systems use a 32-bit bus dedicated to system RAM in order to address more than 16 MB of memory. Adapter cards, however, are restricted to the addressing capabilities of the bus architecture. The 16- bit ISA bus has a physical limitation that restricts its addressing capabilities to a maximum of 16 MB of RAM.

The 2 MB Memory Aperture feature on the Graphics Ultra Pro and Plus must be placed at a memory interval of at least 2 MB above the last address in system memory. Therefore, NOTE: The above restriction also applies to EISA-bus-based 386 and 486 systems with an ISA Graphics Ultra Pro or Plus installed. The EISA Graphics Ultra Pro and Plus does not have this problem.

Graphics Ultra Pro and Plus are manufactured by ATI, a vendor independent of Microsoft; we make no warranty, implied or otherwise, regarding these products' performance or reliability.