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mov ax, 4001h   ; Notify Background Switch
int 2fh
 
Notify Background Switch notifies a VM application that it is being switched
to the background. The VM application can carry out any actions, but should
do so within 1000ms. This is the amount of time the system waits before
switching the application.
 
Return Value
 
This function has no return value.
 
Comments
 
After switching to the background, the application continues to run unless
it attempts to access video memory. If the video adapter is in a video mode
that the virtual display device (VDD) does not support in the background,
the VDD freezes the application until the application can be switched back
to the foreground.
 
VM applications that have called Enable VM-Assisted Save/Restore (Interrupt
2Fh Function 4000h) should avoid accessing video memory and registers to
avoid being frozen. Applications that have not called Enable VM-Assisted
Save/Restore, call access video memory and registers since the VDD saves
theses after this function returns.
 
 
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