Early computer art by Barbara Nessim (1984).

The chunky scan-line gaps in between the rows of pixels are the result of these images being photographs of the monitor on which they were displayed. Screenshots had existed since the 1960s but in the 1980s getting such an image off a mainframe was not yet easy or universal. Instead images were saved by pointing a camera at the screen, in this case a Video Image Recorder, capturing the image on 35mm slide film, and printing them by cibachrome process.