column 80

Due to inheriting constraints first introduced by [IBM] in the design of popular [punch card]s they introduced in 1928, for nearly a century and running the default width of a typical [terminal] has been to accommodate up to 80 columns of text characters. Hence, most ANSI art illustrations have been drawn to fit within an 80-character window of width. (Historically, wider ANSI canvases were saved as .[BIN] files and often programmed into bouncy executables by Tasmaniac of ACiD. Today .[XBIN] is the format used for extra-wide ANSIs.)

If you look carefully at the edges, you will note that many ANSI artists actually only draw up to the 79th column and leave the 80th blank. What's that about? Column 80 is a precarious place: if at any point you try adding an 81st character, it will be automatically bumped along to serve as character 1 of the next line. The way that ANSI art is usually communicated, colour control codes are sent along with character codes, all targeting the ultimate display of a coloured character at one specific location on the screen. Now, while the ANSI system does allow for very precise instructions for the explicit situation of specific characters at particular places on the screen (this is how ANSImation works) most characters' locations are lazily implied by simply assuming they're going up in the next available location following the printing of the previous character. Some terminals sometimes receive colour control codes targeting the last available spot on the line before understanding their intended purpose, and upon receiving character codes, automatically send them to the start of the next line. On BBSes especially, this often results in full 80-column ANSI art being displayed in an unwanted jagged, every-other-line-alternating-with-a-mostly-blank-line fashion. This heinous display glitch can be consciously sidestepped by simply not using the 80th column.

Even though most ANSI art of the 21st century has not been drawn with the intention of having it be displayed on a BBS, old habits die hard, and many old nerds are simply happy to uphold a tradition of always keeping things as backward-compatible as possible.