Someone has written a description on how to enable printing from HP calculators. The hardware device (a small battery operated IR connected thermal printer) that HP made for this seems to have been terminated a long time ago, but I did write an MS-DOS application more than 10 years ago to emulate it. Apparently that piece of software is still the best way of getting hardcopy output from a HP calculator at this time (taking trouble to run it in an MS-DOS emulator, as it does not seem to run in XP+).
Maybe I should try to find if I have the source code of it somewhere (or just use the printer code information on my own site to work from scratch) and construct an up to date application written in .NET to emulate the printer under Windows…? <grin>