INT 15 - MultiDOS Plus - WAIT FOR EVENT
        AX = 1E02h
        DX = event/trigger number (00h-3Fh)
Return: AH = status
            00h successful
            01h invalid event/trigger number
Note:   if the event counter is zero, the task is suspended until the event is
          triggered with AX=1E01h; else, the counter is decremented and the
          call returns immediately
SeeAlso: AX=1E01h