Actually, that's debatable. First, most 80 columns cards had the last 8 columns ignored (or used for metadata). Second, it is much more probable that 80 columns

Actually, that's debatable. First, most 80 columns cards had the last 8 columns ignored (or used for metadata). Second, it is much more probable that 80 columns limit comes from 80x25 text resolution of EGA/VGA displays.