INT 6B - Novell NASI/NACS, Ungermann-Bass Net One SERIAL I/O - BUFFERED WRITE   
	AX = 0000h
	CX = length
	ES:BX -> buffer
Return: CX = number of bytes written
Program: NASI is Novell's NetWare Asynchronous Services Interface (purchased
	  from Network Products Corp, who call it NCSI) which runs on
	  workstations; NACS is the NetWare Asynchronous Communications
	  Services module which runs on servers
InstallCheck:	test for the signature string "NCSI" three bytes past the
	  interrupt handler; see also AH=02h.
	As of version 3.0, Novell's NASI can be distinguished from NPC's
	  NCSI by the presence of an 'A' immediately following the signature
Notes:	this function is also supported by TelAPI, NPC NCSI, and Connection
	  Manager CLIENT.EXE; for TelAPI, nonzero values in AL specify a
	  connection ID
	Connection Manager returns CF set/AL=FFh if called while an INT 6B
	  call is already in progress
SeeAlso: AX=0100h,AH=18h,INT 14/AH=19h,INT 14/AH=E3h