Interrupt 2Fh Function 1681h

mov     ax, 1681h   ; Begin Critical Section
int     2Fh         ; multiplex interrupt
 

Begin Critical Section (Interrupt 2Fh Function 1681h) prevents Windows from switching execution from the current VM to some other. MS-DOS device drivers and TSRs use this function to prevent a task-switch from occurring.

This function has no parameters.

This function has no return value.

When a virtual machine is in a critical section, no other task will be allowed to run except to service hardware interrupts. For this reason, the critical section should be released using End Critical Section (Interrupt 2Fh Function 1682h) as soon as possible.

See Also

Interrupt 2Fh Function 1682h End Critical Section