There are links to several in the 48HP Wikipedia, down in the emulator segment. page.
https://en.wikipedia.org/wiki/HP_48_series.
Not sure which would be best...guessing X48 at
https://github.com/dparnell/i48
Emulators[edit]
Emu48 for Windows
X48 for Mac OS X, POSIX (Unix/Linux)
i48 - HP48GX emulator for iOS, based on X48
m48 – HP48 emulator for the iPhone, based on Emu48
Droid48 – HP48G Emulator for Android, based on X48
droid48sx – HP48SX Emulator for Android, based on Droid48
An HP48 emulator – decompiler for Unix/Linux or Windows (using Cygwin) by Paul Courbis