| Fun fact: 80 characters comes from punch cards, specifically the IBM card format, introduced in 1928. It improved on competing card formats by having rectangular holes which allowing tighter packing of holes. The result was 80 columns and 10 rows per card. Each column on a card indicates a single character or number, so a whole punch card is the equivalent to a single line of text (and was usually treated as such for programming). Originally, there were only one or two holes punched in each column, providing just enough data for uppercase letters and numbers. But this slowly increased over the years, allowing more characters to be encoded. IBM introduced the EBCDIC standard in 1964, which enabled up to 6 different punched holes per column, encoded in eight bits. This corresponded with the development of the System/360. When terminals were first introduced, they were designed to be compatible with 80 characters per line, as you would expect. Starting with 40 characters per line in the early 60s, eventually terminals like the IBM 3270 had 80 columns as the norm. This was then copied by microcomputers. The Commodore PET launched with 80 x 25 character support right away. The Apple II originally had 40 characters per line, but they also sold an "Extended 80-Column Text Card" extension board to allow 80 characters (as requested by VisiCalc). This was built in to the business focused Apple III, and later into the IIe. The "e" in IIe stands for "extended". The original IBM PC's Monochrome Display Adapter had a 720 x 350 display, with each character contained in a 9 x 14 box. 720/9 = 80. As higher resolutions became the norm, editors began to put a line on the screen to visually indicate 80 characters. Certain programming languages have an 80 character per line limit like COBOL or FORTRAN, so the line did serve a purpose at first. But later it became sort of vestigial. And here we are now, a century later, debating whether 80 characters is still a good line limit for code. |