Format of DR Multiuser DOS AUX device control block:
Offset	Size	Description	)
 00h	BYTE	function (00h get, 01h set)
 01h	BYTE	DTR state (00h low, 01h high, FFh unknown/don't change)
 02h	BYTE	RTS state (00h low, 01h high, FFh unknown/don't change)
 03h	BYTE	DSR state (00h low, 01h high, FFh unknown/don't change)
 04h	BYTE	CTS state (00h low, 01h high, FFh unknown/don't change)
 05h	BYTE	DCD state (00h low, 01h high, FFh unknown/don't change)
 06h	BYTE	RI state (00h inactive, 01h active, FFh unknown/don't change)