One of the pioneers of utilization of computers for creating a visual concrete poetry effect according to Funkhouser in Prehistoric Digital Poetry is Lillian F. Schwartz. Schwartz is typical of an early innovator, she is primarily an explorative artist who made contributions to vision theory, many documentary films as well as creating this poetic work. Observances cited in Funkhouser (p.104) is primarily a visual fx that has become a common filter: altering the opacity of characters to create a subliminal image. The classic ASCII face. The image below utilizes a poem by Laurens R. Schwartz, is cropped, and was originally published in McCauley, Computers and Creativity (1974):

The bio on her website outlines the earliness of Schwartz’s involvement with computation:

Schwartz began her computer art career as an offshoot of her merger of art and technology, which culminated in the selection of her kinetic sculpture, Proxima Centauri, by The Museum of Modern Art for its epoch-making 1968 Machine Exhibition.