Int 2F Fn DE01  U - Quarterdeck Qdpmi.sys V1.0 - Installation Check        [Q]

   AX = DE01h
   BX = 4450h ("DP")
   CX = 4D49h ("MI")
   DX = 3039h ("09")

Return: AL = FFh if installed
       BX = 4D42h ("MB")
       CX = 4921h ("I!")
       DX = 8F4Fh
       ES:DI -> filename of DPMI host overlay

Note:  the installation check consists of testing for the existence of the
     character device QDPMI$$$

See Also: INT 2F/AX=1687h,INT 31/AX=0000h
Index: installation check;QDPMI