Int 31 Fn 0900  P - Dpmi 0.9+ - Get And Disable Virtual Interrupt State    [E]

   AX = 0900h

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

Notes: the previous state may be restored simply by executing another INT 31
   a CLI 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=0901h,AX=0902h