There were two major trends in the 1984 time frame that impacted culture in a way that discouraged girls from entering computing: the proliferation of computers used primarily by boys for video games, and a slew of movies starring male geeks using technology for battle and babes.
By 1984, the importance of computing for business had been established and hero Bill Gates' place in the cultural consciousness was cemented with his first Time magazine cover in April. But something even more revolutionary happened in 1984 -- Apple launched the MacIntosh. Home computers were overwhelmingly advertised for boys (see videos below), and the most common application was games most popular with boys.
Also around 1984, the biggest movie phenomena were Terminator, in which a robot was a killing machine; and Return of the Jedi, in which technology was a tool of battle and the princess was a captive in a bikini.
Other hit movies of that era were War Games, in which a boy challenges a computer to a game of global thermonuclear war; Weird Science, in which boys hack into a computer in order to construct an ideal girlfriend; and Revenge of the Nerds, in which the boys use technology to spy on a girls' bathroom.