INT 2F - MS WINDOWS 3+ - BEGIN CRITICAL SECTION
AX = 1681h
Notes:  used to prevent a task switch from occurring
should be followed by an INT 2F/AX=1682h call as soon as possible
nested calls are allowed, and must be followed by an appropriate number
of "end critical section" calls
not supported in Windows/386 2.x. Get INDOS flag with INT 21/AH=34h and
and increment by hand.
SeeAlso: INT 15/AX=101Bh,INT 21/AH=34h

See also: 2F1682

2F1681 - MS WINDOWS 3+ - BEGIN CRITICAL SECTION