HP application pac manuals are on this site, indexed at
http://www.hp41.org/LibView.cfm?Command ... egoryID=74 . You might also want to see if the financial part of the Advantage module will do what you want. See
http://www.hp41.org/Archive.cfm for lots more material. Know also that engineers have introduced a lot of new HP-41 modules in the last few years, some being indexed at
http://systemyde.com/hp41/documents.html . Angel Martin is a particularly prolific writer of application pacs in MCode, ie, machine language, for maximum performance. His 41z module for example gives the 41 a 4-level, essentially native complex-number stack and well over 100 complex-number functions written in MCode; and of the few that the Advantage module duplicates, Angel's is approximately ten times as fast. You can put quite a few ROM module images in a single physical module with flash memory produced by Diego Diaz. See
http://www.clonix41.org/ . Note however that he builds them into existing plastic shells which are becoming hard to come by; so if you have a module you won't need anymore, it would be good to send that to him to build his into, and then again you can have several ROM module images flashed into it, so it's like having a bunch of modules in one port. I have the Clonix-41. I have a lot of HP-41 links on my site's links page's HP-41 section, at
http://wilsonminesco.com/links.html#hp41 .