From an old news report — it used to take about two hours to download an electronic newspaper with connections fees of five dollars per hour. Oh, and the newspapers weren’t in it to make a profit.
Pen plotters print by moving a pen across the surface of a piece of paper. When computer memory was very expensive, and processor power was very limited, this was often the fastest way to efficiently produce very large drawings or color high-resolution vector-based artwork.
That would’ve been some fun programming.