Note: I had diffcult time finding 6800 (68B00 same CPU
but it's 2MHz)
 datasheet.  Still couldn't find it except for pinout which helped me
 to figure out that one terminal. 
    http://www.datasheetarchive.com/search.php?q=6800&sType=part&ExactD…
    Datasheetarchive is your friend ;o)