Int 7C Fn 0016  - Sk-upps Data Link Interface API - Dli 2.8+ - Driver I/o  [N]

   AX = 0016h
   DX = subfunction; bits 14-15 specify direction of I/O:
       00 no data at all (ES:BX undefined)
       01 driver -> application (GET)
       10 application -> driver (SET)
       11 both directions (GET/SET)
   ES:BX -> I/O buffer (optional)
   CX = size of buffer (if ES:BX valid)

Return: AX = completion code; defined by OEM
Program: SK-UPPS is the Schneider & Koch Universal Portable Protocol Stack,
     which provides an API on top of its Data Link Interface, allowing the
     use of any of several network transport layers

Notes: not supported by all DLIs (will return AX=FFFFh if not supported)
   subfunction codes are defined by OEMs

See Also: AX=0001h