Punched cards generally use one column of holes for each digit or letter. But there was no worldwide standard for the number of columns, the size of the card, or the shape of the hole. In 1928, IBM switched to rectangular holes on 80-column cards. Powers-Samas in the UK continued to uses round holes, and over the years had cards with 21, 26, 40, 65, and 80 columns. In the 1970s, IBM introduced a 96-column card with very tiny round holes.