Your best option to convert old documents (like .wls files from 602tab) to PDF would be to use some of the PDF converters with broad file support. That is especially useful when you do not have access to the original software that was used to save the .wls file in first place.
Convert 602Tab spreadsheet to Adobe Portable document format.
We have found one software suitable in our database for this conversion.
On-line services software - convert wls to pdf on web
Free PDF Converter is a online web-based document to PDF converter software that is able to convert various types of document file types such as DOC, XLS, PS, PPT, RTF and others to PDF.
Convert from wls file
to pdf file
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.