Ha, I didn't even notice the chain hanger in the photo! Regardless, I went back and looked at my 1980's Norco literature. 1986 was the year that most Norco models went to the routing cables under the BB shell. However, they went to top tube cable tunnels, shifter bosses and forged dropouts at the same time. There was also no chrome on any of the frames. In fact there was no chrome as far back as 1982 and the cable stops in use then were more refined than this one.
Assuming it is a Norco, the cable routing would appear to be an anomaly. As the for the age, it appears to pre-date 1982 and to the best of my knowledge Norco expanded their brand into bicycles in 1978, so you're looking at 1978-1981.