Format of VINES terminal status area:
Offset	Size	Description	)
 00h	BYTE	status of session: 4Eh=oNline, 46h=oFfline, 57h=Waiting
 01h	BYTE	terminal type (00h=VT100, 01h=TTY, 02h=VT52, 03h=IBM3101)
 02h	BYTE	current keypad mode (VT100,VT52 only)
		4Eh ("N") numeric mode
		41h ("A") application mode
 03h  4 BYTEs	current state of LEDs (VT100 only)
		00h off
		01h on
 07h	WORD	line error count
 09h	WORD	primary error code (see #03373)
 0Bh	WORD	secondary error code