Peseta was a common name for the coin that equal ⅕ of a peso. Then it was formally approved as a currency unit in 1868 at this time Spain was part of the Latin Monetary Union. The peseta was the official currency for Spain from 1868 until 2002.
Before modern times there was no particular written symbol or character to represent peseta, and other common abbreviations were used like ‘pt’ ‘PTA’ ‘pts.’
After inventing the Spanish version of the mechanical typewriter, it had the expression ‘pts’ on a single button to fill a one type space. In 1980 IBM include the ‘pts’ symbol in its computers.