HP-41C disk drive.

[Dave Britten]

You'll want to consult the HP-IL adapter manual for the specifics. Section 3 has all the details of mass storage operations.

If this was a backup created with WRTA, then you should be able to load it with READA. Put the filename into the alpha register first, as with most of the other storage commands.

The USB interface you've heard about is probably the PIL-Box. I've got one that I use with my 41 and 71B. It's a must-have if you're into HP-IL! You run the ilper software on your computer, and it emulates an HP disk drive.

http://www.jeffcalc.hp41.eu/hpil/