Int E0  - Dr Multiuser DOS - "a_cattach" - Conditionally Attach To Aux De  [O]

   CL = A7h

Return: AX = status
       0000h attached
       FFFFh unable to attach
Desc:  attaches the default auxiliary device to the calling process if it is
     available

Note:  does not block if the device is already in use

See Also: INT E0/CL=A5h,INT E0/CL=A6h,INT E0/CL=A8h,INT E0/CL=B0h