Hoppi
An application for Apple macOS to allow communication with Hewlett-Packard RPL-based calculators using the Kermit file transfer protocol. Both USB and RS232 calculator ports are supported (where available) on the HP48S, HP48SX, HP48G, HP48GX, HP48G+, HP48GII, HP49G, HP49G+ and HP50G calculators.
The latest version of Hoppi, version 2, is available here:-
Previous releases can be downloaded from here.
See Eric Rechlin's excellent site www.hpcalc.org for (a lot) more information on these calculators.