US letter-size paper is 8.5 "inches" wide (215.9mm), which means that 10-character-per-inch pica type can print almost exactly one 80-column IBM punched card across the width of the page. Is this coincidence?
Certainly by the time of the Selectric (01961) IBM was already making computer printers (for example, the IBM 1403 in 01959) which were used to print pages full of card images as well as computer output, and indeed the IBM 407 had been printing pages full of card images since 01949, when IBM still wasn't going to sell computers. The 407 was 10 characters per "inch" but used 120-character-wide paper: https://en.wikipedia.org/wiki/IBM_407
And I doubt that the 407 was much of an influence on typewriter design in the 01950s, and certainly couldn't have been before that. But I have the impression that Pica typewriters were already a thing; in August the house we rented for vacation had a Royal KHM typewriter from 01942 with decimal tabulator keys, and if it wasn't 10 characters per inch, it was awfully close.
IBM's original punched cards had 12 rows, 24 columns, and round holes, but in 01928 they introduced the 80-column IBM card, which was 187mm wide, including some margin, so the character spacing was a bit closer than 10 per "inch". But at the time the cards still didn't support alphabetic data; that wouldn't come until 01931.
So, was it just coincidence that the punched cards that were so influential on early computer data formats (including programming languages such as FORTRAN) were within a few percent of the width of the most common typewriters? Or is there a common cause I'm not seeing?
akdor1154•3h ago