"Mainframe Experimentalism" challenges the conventional wisdom that the digital arts arose out of Silicon Valley's technological revolutions in the 1970s. In fact, in the 1960s, a diverse array of artists, musicians, poets, writers, and filmmakers around the world were engaging with mainframe and mini-computers to create innovative new artworks that contradict the stereotypes of "computer art". Juxtaposing the original works alongside scholarly contributions by well-established and emerging scholars from several disciplines, "Mainframe Experimentalism" demonstrates that the radical and experimental aesthetics and political and cultural engagements of early digital art stand as precursors for the mobility among technological platforms, artistic forms, and social sites that has become commonplace today.