There was no such thing as a Rubik's Cube in the 1970s.
OK, there was a magic cube that you could easily scramble but was harder to unscramble. I still have a vintage example from November 1979. But it wasn't until 1980 that it hit the shops and acquired the "Rubik" name.
 I can place it that precisely because it was my first term at Cambridge, when I regarded it as a practical exercise in Group Theory - one of the term's main courses.