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include vdd.inc VxDcall VDD_Query_Access |
The VDD_Query_Access service specifies whether video memory can be accessed. Virtual devices that call software in the virtual machine use this service to determine whether a video display error will occur if the software attempts to access video memory.
EBX
Specifies the address of the control block.
The carry flag is clear if a virtual device can access video memory.
The virtual device should call this service just before returning to the virtual machine such as while processing a virtual machine event. If the video memory cannot be accessed, the virtual device should avoid calling software that may attempt access even if not calling the software causes another error, such as leaving the mouse cursor on when the virtual machine runs in a window.
Flags