You could have downloaded cs-41 RPN calculator 6.4 for Mac from our application library for free. The actual developer of this software for Mac is AD&A Multimedia. The application lies within Productivity Tools, more precisely Calculators.
From the developer:
The cs-41 app contains near all the built-in functions of the original HP-41C (including sounds) and the ability to save and restore limited programs in "module" files, so you can modify routines, start new ones, erase the memory, quit and reopen the app without worry - the saved modules will remain intact. With this new release, the app fills a lack that could difficult it's usability if you want to make and reuse your own programs or routines.
You may want to check out more Mac applications, such as RPN Calculator, Always on Top RPN Calculator or Full Screen RPN Calculator, which might be similar to cs-41 RPN calculator.
Calculators
Science Tools