48sx: The HP48 sx emulator! HP48sx is a vintage RPN calculator. I used this calc 25 years ago; -) I love this calc. And now I can have it in my pocket every day! No nag, no Ad, completely FREE! Droid48sx is a modified version of droid48 but for HP48 SX, credit goes to Arnaud Brochard (author of droid48 for Android) and of course Eddie C. Dost (author of x48 for UNIX).