Format of Datalink Communication Block:
Offset	Size	Description	)
 00h	WORD	portal ID
 02h  6 BYTEs	source address
 08h  6 BYTEs	destination address
 0Eh	DWORD	buffer pointer
 12h	WORD	buffer length
 14h	WORD	operation
 16h	BYTE	pad flag (used on open)
		00h no pad
		01h pad
 17h	BYTE	mode flag (used on open)
		00h 802.3
		01h Ethernet
		02h promiscuous
 18h	DWORD	line status change function
 1Ch	DWORD	received data function
 20h	DWORD	transmitted data function
 24h	BYTE	maximum outstanding transmits/receives
 25h  2 BYTEs	protocol type
 27h	WORD	buffers lost