I did. He didn't. He was a foreign student. I was an American.
Precisely. There was an approximately two year window where those who turned 18 didn’t register for the draft, as there was no registration. ~1976 and 1977. Then Jimmy reinstated registration. Here; it looks like it’s closer to 3 years, most of 1975 too:
“Only men born between March 29, 1957, and December 31, 1959, were completely exempt from Selective Service registration.”
From towards the bottom here:
http://en.wikipedia.org/wiki/Selective_Service#History