Many of the kids today are probably familiar with having to decrypt ROMs to apply patches, this could be written off under that.The assembly hack thing has me curious though, especially as I imagine the gamesharks on the hardware went there at various levels. Doubtless some mods would probably trip anti piracy but as a general concept I am not so sure.Are there any binary checksums/hashes involved? Given the... less concerned approach to security of the time it would probably only do on load patching rather than constant checks too, not to mention a quick scan of http://problemkaputt.de/psx-spx.htm#expansionportpio mentions other things so it would more likely be a chain loader.Edit. Probably should have read the protection chapters as well http://problemkaputt.de/psx-spx.htm#cdromprotectionscexstrings and onwards for a few, including some stuff about XOR decryption in some games.