## Physical Device Driver Reference

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### SCREENDD_SVGA_ID (08h) - Remarks

The screen device driver performs chip detection at initialization time and stores this information in an internal structure. When this IOCtl is called , the internal structure is copied into the data packet. This information is also available by calling OEMHLP$ device, category 80h, Function 08h. For more information, see Category 80h OEMHLP IOCtls. The OEMHLP device driver does not perform the actual detection but queries the physical screen device driver.

Future detection logic for new chip sets can be added to the screen device driver. Both the OEMHLP and Screen IOCtls will return these new values. If an OEM plans to include support for a new chip, the screen device driver's detection logic must be extended. Chip set values from 0-2FFh and FFF0-FFFF are reserved. Chip sets with a value of zero are not supported by OS/2 2.1. This does not imply that OS/2 will not operate or that the operating system will not take advantage of the video adapter installed.

Adapters type 9 (Chips and Technologies) and 11 (Advance Logic) are detected but not supported by IBM in non-VGA modes.

An application can update the video memory information returned in the data packet. However, this update does not affect the screen physical driver's internal configuration or processing. Refer to SCREENDD_UPDATEMEMORY for this function.

Only applications making Function 08h calls after the update receive the revised video memory value.