title_body: How to convert .epub to .pdb for testing
upvoted_answer: There is an old program called TL-PDB. The original authors site seems to be here according to this site, but I have some difficulty reading the original.
  
  You can read about it here and here as well (download sites for free software seem to copy each others content).
  
  Calibre can generate PDB output (not surprisingly as MOBI is a superset of PalmDoc).