Int 31 Fn 0901  P - Dpmi 0.9+ - Get And Enable Virtual Interrupt State     [E]

   AX = 0901h

Return: CF clear
   virtual interrupts enabled
   AL = previous interrupt state (00h disabled, 01h enabled)
   AH preserved

Notes: the previous state may be restored simply by executing another INT 31
   a STI instruction may be used if the previous state is unimportant,
     but should be assumed to be very slow due to trapping by the host

See Also: AX=0900h,AX=0902h