Droid48 is an Android application that emulates the HP 48 scientific calculator using Reverse Polish Notation (RPN). This program is a port of the X48 project, which has its sources available on GitHub. However, it is worth noting that HP 48's "grayscale mode" cannot be emulated.

Droid48 is a great tool for anyone who needs a scientific calculator on their mobile device. The application is easy to use and provides all the functions that one would expect from an HP 48 calculator. Additionally, users can visit hpcalc.org to access a large collection of programs. One cool feature of Droid48 is that users can tap the HP's LCD to show/hide a simpler numeric pad. Overall, Droid48 is a reliable and efficient emulator for those who need a scientific calculator on-the-go.