Just a thought: IBM made a big effort to recruit women into mainframe programming jobs. 1984 roughly when Unix and PCs started to take over the industry; perhaps those companies were not as interested in recruiting women.
Also, you can be sure there's far less sexual harassment now than in the 1970s and 80s.
I personally theorize BBS's, which got popular in the mid 1980s, and later the Internet, gave spiteful and poorly socialized men a anonymous veil. Reddit keeps the legacy of woman-hostility alive and well with comments like "tits or gtfo".
Well, women chose to get the fuck out. The hostile behavior experienced online would never be tolerated in a face to face setting.
Of course it's only a theory and I was too young to remember any first hand experience of the 1980s.
It might be tough to imagine now, but very very few people were online in those days. In the programming forums (Compuserve, Usenet) people generally posted using their real names and job/university affiliation, so the atmosphere was professional at least.
Perhaps some small porn BBSs or IRC channels had a different atmosphere, but the "tits or gtfo" mentality is mostly something which appeared over the last decade or so.
I was a highschool student in the late 89s, early 90s, and I encountered some truly awful stuff on local bbs scenes. At first, I must be ugly and a social outcast (they referred to me as "the burly Russian wrestler"). I shrugged it off, because everyone got shit. So what? Then I went to one of the parties; very few people there had met me before. I was a pretty standard looking 16 year old girl, but I felt like meat, just meat. In the space of 20 minutes, two 20something men hit on me, virtually everyone else expressed shock at my lack of hidiousness, or told me they were surprised I was actually a girl. I begged my older brother to drive me home immediately. Then I buried my former alias, and made a new male alter ego. Just because you didn't see it, doesn't mean it didn't happen.
I have no doubt the BBS world was full of creeps, and that could have been very discouraging to someone getting into computing. My point was that behavior was far more segmented away from mainstream society than (say) Reddit.
1983 was also the year the bottom dropped out of the console market, loads of firms went bankrupt, it was not a good career move to get into the industry in the mid-80s.
Also, you can be sure there's far less sexual harassment now than in the 1970s and 80s.