I recently purchased a DM41L because the HP15 and the HP41C were my favorite computing devices when I was in college.
So far I've been having a ball not only using the calculator but writing software to read/write the memory. The python app I've written works on MacOS and Ubuntu and should work on Windows, and it lets you manage programs, keyboard assignments (including synthetic), extended memory, etc... Check it out on github! https://github.com/mwheinz/DM41L_Explorer

