Format of HUNTER 16 control block:
Offset	Size	Description	)
 00h	WORD	center X co-ordinate
 02h	BYTE	center Y co-ordinate
 03h	WORD	radius in pixels
 05h	BYTE	color (00h white, 01h black, FFh invert)
 06h	BYTE	aspect ratio x:x (1-127)
 07h	BYTE	aspect ratio y:y (1-127)