INT 7C - SK-UPPS Data Link Interface API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running.  Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes. - DLI 2.8+ - DRIVER I/O CONTROL
	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(Original Equipment Manufacturer) a company which purchases components that are resold as part of its own products under the company's own brand name, e.g. a Gateway 2000-branded monitor may actually be a Mag or NEC monitor.
Program: SK-UPPS is the Schneider & Koch Universal Portable Protocol Stack,
	  which provides an API(Application Program[ming] Interface) The defined set of calls which a program may make to interact with or request services of the operating system or environment under which it is running.  Because the inputs and outputs of the calls are well-defined, a program using the API can continue using the identical calls even if the internal organization of the program providing the API changes. 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
SeeAlso: AX=0001h