During the recent 1:2:1, Wendy McMurdo suggested to take a look at works of Christopher Wool - a painter who’s using the letters motif in his large format works.
According to Wikipedia “Wool is best known for his paintings of large, black, stenciled letters on white canvases” a radical and recognisable "word paintings" in which he refers to common phrases or quotes.
I like more his later works which are spectacular. He combines the static, define shapes of the printed letters with the dynamic, spontaneous, gesture lines. Some works dimensions exceed the human scale what brings the shapes of the letters closer to abstract forms than the symbols with recognisable semantic value. He works also with silkscreen and it think those are my favourite. He seems exploring the confrontation of the dynamic, emotional human calligraphy with the austere, machine-made typographic forms.
Other artists I know who explore visually the motif of writing/letter/code:
One of the most famous conceptual Polish painters. His works are fully dedicated to digits which he placed on the canvas in the same hypnotising manner for most of his life. In 1965 he begun the series “"1965 / 1 – ∞"” and painted the continuously growing numbers for the rest of his life. All painting are the same size and have the same neutral background (with some brightness variations)