HP HP48 series calculators will allow transfer of data over RS232 and can send and receive objects as files via the kermit protocol. My goal was to be able to save or read files from an external storage media without needing a host PC to perform the file transfer.
So far I've managed to get a very simple file receive working and am implementing more of the embedded kermit functionality.
git repo is here https://codeberg.org/eugenenine/ArduinoKermit48
I made a bunch of updates. Been working on replacing my proof of concept code with more of the Kermit projects e-kermit code. I'd had to comment out a lot due to lack of resources o the Arduino.
I'm using the decode function from e-kermit now, just modified it a little to use a small fixed file buffer instead of their multiple buffers. Using all of their kermit struct now but added in my file buffer and a the optional fields that HP uses but e-kermit has hard coded.