I was thinking along the same lines (personal computers = more boys interested in CS). Then I found this in the comments section of the article:

http://i111.photobucket.com/albums/n134/im_thatoneguy/CSDegr...

Interesting that there was a dip of both males and females around 1984. So I'm not so sure of the statement above anymore. However, around the year 2000 there's this peak where males do outnumber females by a great deal (even if the number of females joining also increased).

If all these graphs are accurate I'd wonder more about the Y2K rather than 1984...