Int 2F Fn D701  - Banyan Vines V4+ - Get Banv Interrupt Number             [N]

   AX = D701h
   BX = 0000h

Return: AX = 0000h if installed
       BX = interrupt number (60h to 66h)
      nonzero not present

Note:  if AX is nonzero, VINES 3.x or earlier may be installed, thus it is
     necessary to examine the four bytes preceding the handlers for
     INT 60 through INT 66 for the string "BANV"

See Also: AX=D702h,AX=D703h,AX=D704h