Since I’m basically done with my original project, the rewrite of the Apple 1 monitor for the MC6800, I’m now spending my copious free time working on HP-41 stuff. I’m trying to hack together an expansion ROM that will support access to an SD card. Initially I just want to have the equivalent of the HP-IL module DIR, WRTP, and READP functions. I’ll assign it XROM 28 with the full function list of the HP-IL module, but all of the other functions will give a “NONEXISTENT” error, until eventually I get around to implementing more of them.
I haven’t decided whether to finish my assembler written in Python, or use nutstudio.
So far I’ve studied the VASM listings of the HP-IL module’s cassette and control ROM to learn how the DIR, WRTP, and READP functions work.
I doubt that I’ll have this done by the end of this RetroChallenge, but at least I’m making some progress.