Before that, there was the case of ÿ and Ÿ in the base IBM character set (see https://en.wikipedia.org/wiki/Ÿ). The former exists in a handful of proper nouns in French and Hungarian (as in about five proper nouns), but only as a y with a diæresis, which would normally be handled with a Unicode modifier symbol. It is also used in a couple of endangered languages in South America, which would not have influenced the character getting in to a PC character set. It is thought that possibly it was supposed to represent the Dutch "ij" character, but apparently that is never written as "ÿ" in print. Ÿ seems to not be used by any language.