We have found 2 software records in our database eligible for .prn to .xlsm file format conversion.
Old Lotus 1-2-3 formatted text documents (.prn) might still be supported in some programs and can be used for making even more Excel spreadsheets (nowadays mostly .xlsx or .xlsm file).
Older versions of Excel were certainly capable of such conversion, but latest versions no longer support certain file types and maybe support for PRN format will be eventually phased out.
PRN
A prn file extension is related to the Lotus 1-2-3 and Microsoft Excel spreadsheet editors. A prn file stores formatted text.
XLSM
Files with xlsm extension are used for workbooks of spreadsheets created in Microsoft Excel that also include macros, that enhance the functionality of the spreadsheet but some automation features. Other spreadsheets might open xlsm files as well, however they most likely wont be able to use the Excel specific formatting and macros.