Comment by kens

The 80×24 display of the IBM 3270 is the reason that terminal windows nowadays are typically 80×24 (or 25 lines because the IBM PC added an extra line). IBM dominated the CRT terminal market in the mid-1970s, so other manufacturers were mostly forced to 80×24 in order to be compatible. (And of course the IBM 3270 had 80 columns for compatibility with punch cards.)