Important Notice

The pages on this site contain documentation for very old MS-DOS software, purely for historical purposes. If you're looking for up-to-date documentation, particularly for programming, you should not rely on the information found here, as it will be woefully out of date.

                                                     ◄Up► ◄Next► ◄Previous►
────────────────────────────────────────────────────────────────────────────
 
mov ax, 4003h       ; Enter Critical Section
int 2fh
 
Enter Critical Section notifies the virtual-display device that the VM
application has entered a critical section and cannot respond to Save Video
Register State (Interrupt 2Fh Function 4005h).
 
A VM application calls this function when it has started critical section
processing.
 
Return Value
 
This function has no return value.
 
Comments
 
After the VM application enters the critical section, the virtual-display
device postpones calling Save Video Register State for up to 1000ms or until
the VM application calls Exit Critical Section (Interrupt 2Fh Function
4004h), whichever comes first.
 
If time elapses without the VM application calling Exit Critical Section,
the virtual-display device reprograms the video hardware anyway and, when
its operation is complete, calls Notify Foreground Switch (Interrupt 2Fh
Function 4002h) in an attempt to reinitialize the application properly.
 
 
                                      ♦