80 characters was the number of characters a 10-pitch typewriter could fit on a line on standard letter-size paper. 24/25 characters came from the vertical res

80 characters was the number of characters a 10-pitch typewriter could fit on a line on standard letter-size paper. 24/25 characters came from the vertical resolution of CRTs and what you could fit into 2KB of RAM. The point size argument is clearly wrong, as this sample from the early 19th century shows: https://upload.wikimedia.org/wikipedia/commons/4/45/A_Specimen_by_William_Caslon.jpg https://upload.wikimedia.org/wikipedia/commons/4/45/A_Specim...