INT 6B - Novell NASI/NACS, Ungermann-Bass Net One SERIAL I/O - BUFFERED READ    
	AX = 0100h
	CX = length of buffer
	ES:BX -> buffer
Return: CX = number of bytes read
Note:	also supported by TelAPI and NPC NCSI; for TelAPI, nonzero values in
	  AL specify a connection ID
SeeAlso: AX=0000h,AH=19h,INT 14/AH=18h,INT 14/AH=E2h,INT 14/AX=FF02h