Modern computer science is dominated by men. But it hasn't always been this way.<p>A lot of computing pioneers — the people who programmed the first digital computers — were women. And for decades, the number of women studying computer science was growing faster than the number of men. But in 1984, something changed. The percentage of women in computer science flattened, and then plunged, even as the share of women in other technical and professional fields kept rising.<p>What happened?